d: Merge upstream dmd cf63dd8e5, druntime caf14b0f, phobos 41aaf8c26.

D front-end changes:

    - Import dmd v2.099.0-rc.1.
    - The `main' can now return type `noreturn' and supports return
      inference.

D Runtime changes:

    - Import druntime v2.099.0-rc.1.
    - C bindings for stat_t on powerpc-linux has been fixed.

Phobos changes:

    - Import phobos v2.099.0-rc.1.

gcc/d/ChangeLog:

	* d-target.cc (Target::_init): Initialize C type size fields.
	* dmd/MERGE: Merge upstream dmd cf63dd8e5.
	* dmd/VERSION: Update version to v2.099.0-rc.1.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime caf14b0f.
	* src/MERGE: Merge upstream phobos 41aaf8c26.

gcc/testsuite/ChangeLog:

	* gdc.dg/torture/simd7413a.d: Update.
	* gdc.dg/ubsan/pr88957.d: Update.
	* gdc.dg/simd18489.d: New test.
	* gdc.dg/torture/simd21727.d: New test.

16 files changed, 439 insertions, 270 deletions

diff --git a/libphobos/libdruntime/MERGE b/libphobos/libdruntime/MERGE
index 49f6ae282e0..7c0bb573e2b 100644
--- a/libphobos/libdruntime/MERGE
+++ b/libphobos/libdruntime/MERGE
@@ -1,4 +1,4 @@
-55528bd1e963d858eaa63901fc818b957c349fbc
+caf14b0f4ebbae4157aac89368d6278332ee2aa1
 
 The first line of this file holds the git revision number of the last
 merge done from the dlang/druntime repository.
diff --git a/libphobos/libdruntime/core/gc/gcinterface.d b/libphobos/libdruntime/core/gc/gcinterface.d
index e8cdf1109ad..5560c6229ca 100644
--- a/libphobos/libdruntime/core/gc/gcinterface.d
+++ b/libphobos/libdruntime/core/gc/gcinterface.d
@@ -141,13 +141,13 @@ interface GC
      * Retrieve statistics about garbage collection.
      * Useful for debugging and tuning.
      */
-    core.memory.GC.Stats stats() nothrow;
+    core.memory.GC.Stats stats() @safe nothrow @nogc;
 
     /**
      * Retrieve profile statistics about garbage collection.
      * Useful for debugging and tuning.
      */
-    core.memory.GC.ProfileStats profileStats() nothrow @safe;
+    core.memory.GC.ProfileStats profileStats() @safe nothrow @nogc;
 
     /**
      * add p to list of roots
diff --git a/libphobos/libdruntime/core/internal/gc/bits.d b/libphobos/libdruntime/core/internal/gc/bits.d
index d50c38f0d21..3c1bb543460 100644
--- a/libphobos/libdruntime/core/internal/gc/bits.d
+++ b/libphobos/libdruntime/core/internal/gc/bits.d
@@ -60,7 +60,7 @@ struct GCBits
             onOutOfMemoryError();
     }
 
-    wordtype test(size_t i) const nothrow
+    wordtype test(size_t i) const scope @trusted pure nothrow @nogc
     in
     {
         assert(i < nbits);
@@ -70,7 +70,7 @@ struct GCBits
         return core.bitop.bt(data, i);
     }
 
-    int set(size_t i) nothrow
+    int set(size_t i) scope @trusted pure nothrow @nogc
     in
     {
         assert(i < nbits);
@@ -80,7 +80,7 @@ struct GCBits
         return core.bitop.bts(data, i);
     }
 
-    int clear(size_t i) nothrow
+    int clear(size_t i) scope @trusted pure nothrow @nogc
     in
     {
         assert(i <= nbits);
@@ -91,7 +91,7 @@ struct GCBits
     }
 
     // return non-zero if bit already set
-    size_t setLocked(size_t i) nothrow
+    size_t setLocked(size_t i) scope @trusted pure nothrow @nogc
     {
         version (GNU)
         {
@@ -112,7 +112,7 @@ struct GCBits
         }
         else version (D_InlineAsm_X86)
         {
-            asm @nogc nothrow {
+            asm pure @nogc nothrow {
                 mov EAX, this;
                 mov ECX, data[EAX];
                 mov EDX, i;
@@ -123,7 +123,7 @@ struct GCBits
         }
         else version (D_InlineAsm_X86_64)
         {
-            asm @nogc nothrow {
+            asm pure @nogc nothrow {
                 mov RAX, this;
                 mov RAX, data[RAX];
                 mov RDX, i;
diff --git a/libphobos/libdruntime/core/internal/gc/impl/conservative/gc.d b/libphobos/libdruntime/core/internal/gc/impl/conservative/gc.d
index 87c45fb2872..aa51867fc2c 100644
--- a/libphobos/libdruntime/core/internal/gc/impl/conservative/gc.d
+++ b/libphobos/libdruntime/core/internal/gc/impl/conservative/gc.d
@@ -38,6 +38,8 @@ import core.gc.config;
 import core.gc.gcinterface;
 
 import core.internal.container.treap;
+import core.internal.spinlock;
+import core.internal.gc.pooltable;
 
 import cstdlib = core.stdc.stdlib : calloc, free, malloc, realloc;
 import core.stdc.string : memcpy, memset, memmove;
@@ -145,7 +147,6 @@ class ConservativeGC : GC
 
     Gcx *gcx;                   // implementation
 
-    import core.internal.spinlock;
     static gcLock = shared(AlignedSpinLock)(SpinLock.Contention.lengthy);
     static bool _inFinalizer;
     __gshared bool isPrecise = false;
@@ -155,7 +156,7 @@ class ConservativeGC : GC
      *
      * Throws: InvalidMemoryOperationError on recursive locking during finalization.
      */
-    static void lockNR() @nogc nothrow
+    static void lockNR() @safe @nogc nothrow
     {
         if (_inFinalizer)
             onInvalidMemoryOperationError();
@@ -685,7 +686,7 @@ class ConservativeGC : GC
             else if (pagenum + newsz <= pool.npages)
             {
                 // Attempt to expand in place (TODO: merge with extend)
-                if (lpool.pagetable[pagenum + psz] != B_FREE)
+                if (lpool.pagetable[pagenum + psz] != Bins.B_FREE)
                     return doMalloc();
 
                 auto newPages = newsz - psz;
@@ -695,7 +696,7 @@ class ConservativeGC : GC
 
                 debug (MEMSTOMP) memset(p + psize, 0xF0, size - psize);
                 debug (PRINTF) printFreeInfo(pool);
-                memset(&lpool.pagetable[pagenum + psz], B_PAGEPLUS, newPages);
+                memset(&lpool.pagetable[pagenum + psz], Bins.B_PAGEPLUS, newPages);
                 lpool.bPageOffsets[pagenum] = cast(uint) newsz;
                 for (auto offset = psz; offset < newsz; offset++)
                     lpool.bPageOffsets[pagenum + offset] = cast(uint) offset;
@@ -766,7 +767,7 @@ class ConservativeGC : GC
 
             auto lpool = cast(LargeObjectPool*) pool;
             size_t pagenum = lpool.pagenumOf(p);
-            if (lpool.pagetable[pagenum] != B_PAGE)
+            if (lpool.pagetable[pagenum] != Bins.B_PAGE)
                 return 0;
 
             size_t psz = lpool.bPageOffsets[pagenum];
@@ -777,7 +778,7 @@ class ConservativeGC : GC
 
             if (pagenum + psz >= lpool.npages)
                 return 0;
-            if (lpool.pagetable[pagenum + psz] != B_FREE)
+            if (lpool.pagetable[pagenum + psz] != Bins.B_FREE)
                 return 0;
 
             size_t freesz = lpool.bPageOffsets[pagenum + psz];
@@ -785,7 +786,7 @@ class ConservativeGC : GC
                 return 0;
             size_t sz = freesz > maxsz ? maxsz : freesz;
             debug (MEMSTOMP) memset(pool.baseAddr + (pagenum + psz) * PAGESIZE, 0xF0, sz * PAGESIZE);
-            memset(lpool.pagetable + pagenum + psz, B_PAGEPLUS, sz);
+            memset(lpool.pagetable + pagenum + psz, Bins.B_PAGEPLUS, sz);
             lpool.bPageOffsets[pagenum] = cast(uint) (psz + sz);
             for (auto offset = psz; offset < psz + sz; offset++)
                 lpool.bPageOffsets[pagenum + offset] = cast(uint) offset;
@@ -874,11 +875,11 @@ class ConservativeGC : GC
         debug(PRINTF) printf("pool base = %p, PAGENUM = %d of %d, bin = %d\n", pool.baseAddr, pagenum, pool.npages, pool.pagetable[pagenum]);
         debug(PRINTF) if (pool.isLargeObject) printf("Block size = %d\n", pool.bPageOffsets[pagenum]);
 
-        bin = cast(Bins)pool.pagetable[pagenum];
+        bin = pool.pagetable[pagenum];
 
         // Verify that the pointer is at the beginning of a block,
         //  no action should be taken if p is an interior pointer
-        if (bin > B_PAGE) // B_PAGEPLUS or B_FREE
+        if (bin > Bins.B_PAGE) // B_PAGEPLUS or B_FREE
             return;
         size_t off = (sentinel_sub(p) - pool.baseAddr);
         size_t base = baseOffset(off, bin);
@@ -893,7 +894,7 @@ class ConservativeGC : GC
         if (pool.isLargeObject)              // if large alloc
         {
             biti = cast(size_t)(p - pool.baseAddr) >> pool.ShiftBy.Large;
-            assert(bin == B_PAGE);
+            assert(bin == Bins.B_PAGE);
             auto lpool = cast(LargeObjectPool*) pool;
 
             // Free pages
@@ -1094,13 +1095,13 @@ class ConservativeGC : GC
             pool = gcx.findPool(p);
             assert(pool);
             pagenum = pool.pagenumOf(p);
-            bin = cast(Bins)pool.pagetable[pagenum];
-            assert(bin <= B_PAGE);
+            bin = pool.pagetable[pagenum];
+            assert(bin <= Bins.B_PAGE);
             assert(p == cast(void*)baseOffset(cast(size_t)p, bin));
 
             debug (PTRCHECK2)
             {
-                if (bin < B_PAGE)
+                if (bin < Bins.B_PAGE)
                 {
                     // Check that p is not on a free list
                     List *list;
@@ -1299,7 +1300,7 @@ class ConservativeGC : GC
     }
 
 
-    core.memory.GC.Stats stats() nothrow
+    core.memory.GC.Stats stats() @safe nothrow @nogc
     {
         typeof(return) ret;
 
@@ -1332,13 +1333,20 @@ class ConservativeGC : GC
     //
     // Implementation of getStats
     //
-    private void getStatsNoSync(out core.memory.GC.Stats stats) nothrow
+    private void getStatsNoSync(out core.memory.GC.Stats stats) @trusted nothrow @nogc
     {
-        foreach (pool; gcx.pooltable[0 .. gcx.npools])
+        // This function is trusted for two reasons: `pool.pagetable` is a pointer,
+        // which is being sliced in the below foreach, and so is `binPageChain`,
+        // also sliced a bit later in this function.
+        // However, both usages are safe as long as the assumption that `npools`
+        // defines the limit for `pagetable`'s length holds true (see allocation).
+        // The slicing happens at __LINE__ + 4 and __LINE__ + 24.
+        // `@trusted` delegates are not used to prevent any performance issue.
+        foreach (pool; gcx.pooltable[])
         {
             foreach (bin; pool.pagetable[0 .. pool.npages])
             {
-                if (bin == B_FREE)
+                if (bin == Bins.B_FREE)
                     stats.freeSize += PAGESIZE;
                 else
                     stats.usedSize += PAGESIZE;
@@ -1346,13 +1354,13 @@ class ConservativeGC : GC
         }
 
         size_t freeListSize;
-        foreach (n; 0 .. B_PAGE)
+        foreach (n; 0 .. Bins.B_PAGE)
         {
             immutable sz = binsize[n];
             for (List *list = gcx.bucket[n]; list; list = list.next)
                 freeListSize += sz;
 
-            foreach (pool; gcx.pooltable[0 .. gcx.npools])
+            foreach (pool; gcx.pooltable[])
             {
                 if (pool.isLargeObject)
                     continue;
@@ -1381,7 +1389,7 @@ enum
 }
 
 
-enum
+enum Bins : ubyte
 {
     B_16,
     B_32,
@@ -1405,10 +1413,6 @@ enum
     B_MAX,
 }
 
-
-alias ubyte Bins;
-
-
 struct List
 {
     List *next;
@@ -1416,12 +1420,12 @@ struct List
 }
 
 // non power of two sizes optimized for small remainder within page (<= 64 bytes)
-immutable short[B_NUMSMALL + 1] binsize = [ 16, 32, 48, 64, 96, 128, 176, 256, 368, 512, 816, 1024, 1360, 2048, 4096 ];
-immutable short[PAGESIZE / 16][B_NUMSMALL + 1] binbase = calcBinBase();
+immutable short[Bins.B_NUMSMALL + 1] binsize = [ 16, 32, 48, 64, 96, 128, 176, 256, 368, 512, 816, 1024, 1360, 2048, 4096 ];
+immutable short[PAGESIZE / 16][Bins.B_NUMSMALL + 1] binbase = calcBinBase();
 
-short[PAGESIZE / 16][B_NUMSMALL + 1] calcBinBase()
+short[PAGESIZE / 16][Bins.B_NUMSMALL + 1] calcBinBase()
 {
-    short[PAGESIZE / 16][B_NUMSMALL + 1] bin;
+    short[PAGESIZE / 16][Bins.B_NUMSMALL + 1] bin;
 
     foreach (i, size; binsize)
     {
@@ -1440,7 +1444,7 @@ short[PAGESIZE / 16][B_NUMSMALL + 1] calcBinBase()
 
 size_t baseOffset(size_t offset, Bins bin) @nogc nothrow
 {
-    assert(bin <= B_PAGE);
+    assert(bin <= Bins.B_PAGE);
     return (offset & ~(PAGESIZE - 1)) + binbase[bin][(offset & (PAGESIZE - 1)) >> 4];
 }
 
@@ -1448,9 +1452,9 @@ alias PageBits = GCBits.wordtype[PAGESIZE / 16 / GCBits.BITS_PER_WORD];
 static assert(PAGESIZE % (GCBits.BITS_PER_WORD * 16) == 0);
 
 // bitmask with bits set at base offsets of objects
-immutable PageBits[B_NUMSMALL] baseOffsetBits = (){
-    PageBits[B_NUMSMALL] bits;
-    foreach (bin; 0..B_NUMSMALL)
+immutable PageBits[Bins.B_NUMSMALL] baseOffsetBits = (){
+    PageBits[Bins.B_NUMSMALL] bits;
+    foreach (bin; 0 .. Bins.B_NUMSMALL)
     {
         size_t size = binsize[bin];
         const top = PAGESIZE - size + 1; // ensure <size> bytes available even if unaligned
@@ -1475,7 +1479,6 @@ private void set(ref PageBits bits, size_t i) @nogc pure nothrow
 
 struct Gcx
 {
-    import core.internal.spinlock;
     auto rootsLock = shared(AlignedSpinLock)(SpinLock.Contention.brief);
     auto rangesLock = shared(AlignedSpinLock)(SpinLock.Contention.brief);
     Treap!Root roots;
@@ -1491,11 +1494,9 @@ struct Gcx
     debug(INVARIANT) bool inCollection;
     uint disabled; // turn off collections if >0
 
-    import core.internal.gc.pooltable;
-    private @property size_t npools() pure const nothrow { return pooltable.length; }
     PoolTable!Pool pooltable;
 
-    List*[B_NUMSMALL] bucket; // free list for each small size
+    List*[Bins.B_NUMSMALL] bucket; // free list for each small size
 
     // run a collection when reaching those thresholds (number of used pages)
     float smallCollectThreshold, largeCollectThreshold;
@@ -1508,7 +1509,7 @@ struct Gcx
     else
         alias leakDetector = LeakDetector;
 
-    SmallObjectPool*[B_NUMSMALL] recoverPool;
+    SmallObjectPool*[Bins.B_NUMSMALL] recoverPool;
     version (Posix) __gshared Gcx* instance;
 
     void initialize()
@@ -1592,9 +1593,8 @@ struct Gcx
 
         debug(INVARIANT) initialized = false;
 
-        for (size_t i = 0; i < npools; i++)
+        foreach (Pool* pool; this.pooltable[])
         {
-            Pool *pool = pooltable[i];
             mappedPages -= pool.npages;
             pool.Dtor();
             cstdlib.free(pool);
@@ -1635,7 +1635,7 @@ struct Gcx
             if (!inCollection)
                 (cast()rangesLock).unlock();
 
-            for (size_t i = 0; i < B_NUMSMALL; i++)
+            for (size_t i = 0; i < Bins.B_NUMSMALL; i++)
             {
                 size_t j = 0;
                 List* prev, pprev, ppprev; // keep a short history to inspect in the debugger
@@ -1752,7 +1752,7 @@ struct Gcx
         ConservativeGC._inFinalizer = true;
         scope (failure) ConservativeGC._inFinalizer = false;
 
-        foreach (pool; pooltable[0 .. npools])
+        foreach (pool; this.pooltable[])
         {
             if (!pool.finals.nbits) continue;
 
@@ -1816,18 +1816,18 @@ struct Gcx
     /**
      * Computes the bin table using CTFE.
      */
-    static byte[2049] ctfeBins() nothrow
+    static Bins[2049] ctfeBins() nothrow
     {
-        byte[2049] ret;
+        Bins[2049] ret;
         size_t p = 0;
-        for (Bins b = B_16; b <= B_2048; b++)
+        for (Bins b = Bins.B_16; b <= Bins.B_2048; b++)
             for ( ; p <= binsize[b]; p++)
                 ret[p] = b;
 
         return ret;
     }
 
-    static const byte[2049] binTable = ctfeBins();
+    static immutable Bins[2049] binTable = ctfeBins();
 
     /**
      * Allocate a new pool of at least size bytes.
@@ -1994,7 +1994,7 @@ struct Gcx
 
         bool tryAlloc() nothrow
         {
-            foreach (p; pooltable[0 .. npools])
+            foreach (p; this.pooltable[])
             {
                 if (!p.isLargeObject || p.freepages < npages)
                     continue;
@@ -2094,10 +2094,11 @@ struct Gcx
         }
 
         // Allocate successively larger pools up to 8 megs
-        if (npools)
-        {   size_t n;
+        if (this.pooltable.length)
+        {
+            size_t n;
 
-            n = config.minPoolSize + config.incPoolSize * npools;
+            n = config.minPoolSize + config.incPoolSize * this.pooltable.length;
             if (n > config.maxPoolSize)
                 n = config.maxPoolSize;                 // cap pool size
             n /= PAGESIZE; // convert bytes to pages
@@ -2139,9 +2140,8 @@ struct Gcx
     List* allocPage(Bins bin) nothrow
     {
         //debug(PRINTF) printf("Gcx::allocPage(bin = %d)\n", bin);
-        for (size_t n = 0; n < npools; n++)
+        foreach (Pool* pool; this.pooltable[])
         {
-            Pool* pool = pooltable[n];
             if (pool.isLargeObject)
                 continue;
             if (List* p = (cast(SmallObjectPool*)pool).allocPage(bin))
@@ -2275,7 +2275,7 @@ struct Gcx
 
         // let dmd allocate a register for this.pools
         auto pools = pooltable.pools;
-        const highpool = pooltable.npools - 1;
+        const highpool = pooltable.length - 1;
         const minAddr = pooltable.minAddr;
         size_t memSize = pooltable.maxAddr - minAddr;
         Pool* pool = null;
@@ -2300,7 +2300,6 @@ struct Gcx
                         bitpos -= rng.bmplength;
                         rng.pbase += rng.bmplength;
                     }
-                    import core.bitop;
                     if (!core.bitop.bt(rng.ptrbmp, bitpos))
                     {
                         debug(MARK_PRINTF) printf("\t\tskipping non-pointer\n");
@@ -2335,7 +2334,7 @@ struct Gcx
                     printf("\t\tfound pool %p, base=%p, pn = %lld, bin = %d\n", pool, pool.baseAddr, cast(long)pn, bin);
 
                 // Adjust bit to be at start of allocated memory block
-                if (bin < B_PAGE)
+                if (bin < Bins.B_PAGE)
                 {
                     // We don't care abou setting pointsToBase correctly
                     // because it's ignored for small object pools anyhow.
@@ -2356,7 +2355,7 @@ struct Gcx
                         goto LaddRange;
                     }
                 }
-                else if (bin == B_PAGE)
+                else if (bin == Bins.B_PAGE)
                 {
                     biti = offset >> Pool.ShiftBy.Large;
                     //debug(PRINTF) printf("\t\tbiti = x%x\n", biti);
@@ -2376,7 +2375,7 @@ struct Gcx
                         goto LaddLargeRange;
                     }
                 }
-                else if (bin == B_PAGEPLUS)
+                else if (bin == Bins.B_PAGEPLUS)
                 {
                     pn -= pool.bPageOffsets[pn];
                     biti = pn * (PAGESIZE >> Pool.ShiftBy.Large);
@@ -2429,7 +2428,7 @@ struct Gcx
                 else
                 {
                     // Don't mark bits in B_FREE pages
-                    assert(bin == B_FREE);
+                    assert(bin == Bins.B_FREE);
                 }
             }
         LnextPtr:
@@ -2526,9 +2525,8 @@ struct Gcx
     {
         debug(COLLECT_PRINTF) printf("preparing mark.\n");
 
-        for (size_t n = 0; n < npools; n++)
+        foreach (Pool* pool; this.pooltable[])
         {
-            Pool* pool = pooltable[n];
             if (pool.isLargeObject)
                 pool.mark.zero();
             else
@@ -2598,10 +2596,9 @@ struct Gcx
         size_t freedLargePages;
         size_t freedSmallPages;
         size_t freed;
-        for (size_t n = 0; n < npools; n++)
+        foreach (Pool* pool; this.pooltable[])
         {
             size_t pn;
-            Pool* pool = pooltable[n];
 
             if (pool.isLargeObject)
             {
@@ -2612,12 +2609,12 @@ struct Gcx
                 {
                     npages = pool.bPageOffsets[pn];
                     Bins bin = cast(Bins)pool.pagetable[pn];
-                    if (bin == B_FREE)
+                    if (bin == Bins.B_FREE)
                     {
                         numFree += npages;
                         continue;
                     }
-                    assert(bin == B_PAGE);
+                    assert(bin == Bins.B_PAGE);
                     size_t biti = pn;
 
                     if (!pool.mark.test(biti))
@@ -2637,7 +2634,7 @@ struct Gcx
 
                         debug(COLLECT_PRINTF) printf("\tcollecting big %p\n", p);
                         leakDetector.log_free(q, sentinel_size(q, npages * PAGESIZE - SENTINEL_EXTRA));
-                        pool.pagetable[pn..pn+npages] = B_FREE;
+                        pool.pagetable[pn..pn+npages] = Bins.B_FREE;
                         if (pn < pool.searchStart) pool.searchStart = pn;
                         freedLargePages += npages;
                         pool.freepages += npages;
@@ -2671,7 +2668,7 @@ struct Gcx
                 {
                     Bins bin = cast(Bins)pool.pagetable[pn];
 
-                    if (bin < B_PAGE)
+                    if (bin < Bins.B_PAGE)
                     {
                         auto freebitsdata = pool.freebits.data + pn * PageBits.length;
                         auto markdata = pool.mark.data + pn * PageBits.length;
@@ -2767,7 +2764,7 @@ struct Gcx
                         {
                             pool.freeAllPageBits(pn);
 
-                            pool.pagetable[pn] = B_FREE;
+                            pool.pagetable[pn] = Bins.B_FREE;
                             // add to free chain
                             pool.binPageChain[pn] = cast(uint) pool.searchStart;
                             pool.searchStart = pn;
@@ -2789,7 +2786,8 @@ struct Gcx
 
         assert(freedLargePages <= usedLargePages);
         usedLargePages -= freedLargePages;
-        debug(COLLECT_PRINTF) printf("\tfree'd %u bytes, %u pages from %u pools\n", freed, freedLargePages, npools);
+        debug(COLLECT_PRINTF) printf("\tfree'd %u bytes, %u pages from %u pools\n",
+                                     freed, freedLargePages, this.pooltable.length);
 
         assert(freedSmallPages <= usedSmallPages);
         usedSmallPages -= freedSmallPages;
@@ -2854,12 +2852,12 @@ struct Gcx
     private SmallObjectPool* setNextRecoverPool(Bins bin, size_t poolIndex) nothrow
     {
         Pool* pool;
-        while (poolIndex < npools &&
-               ((pool = pooltable[poolIndex]).isLargeObject ||
+        while (poolIndex < this.pooltable.length &&
+               ((pool = this.pooltable[poolIndex]).isLargeObject ||
                 pool.recoverPageFirst[bin] >= pool.npages))
             poolIndex++;
 
-        return recoverPool[bin] = poolIndex < npools ? cast(SmallObjectPool*)pool : null;
+        return recoverPool[bin] = poolIndex < this.pooltable.length ? cast(SmallObjectPool*)pool : null;
     }
 
     version (COLLECT_FORK)
@@ -2928,7 +2926,6 @@ struct Gcx
         import core.stdc.stdlib : _Exit;
         debug (PRINTF_TO_FILE)
         {
-            import core.stdc.stdio : fflush;
             fflush(null); // avoid duplicated FILE* output
         }
         version (OSX)
@@ -3153,7 +3150,7 @@ Lmark:
 
         // init bucket lists
         bucket[] = null;
-        foreach (Bins bin; 0..B_NUMSMALL)
+        foreach (Bins bin; Bins.B_16 .. Bins.B_NUMSMALL)
             setNextRecoverPool(bin, 0);
 
         stop = currTime;
@@ -3188,24 +3185,24 @@ Lmark:
             auto pn = offset / PAGESIZE;
             auto bins = cast(Bins)pool.pagetable[pn];
             size_t biti = void;
-            if (bins < B_PAGE)
+            if (bins < Bins.B_PAGE)
             {
                 biti = baseOffset(offset, bins) >> pool.ShiftBy.Small;
                 // doesn't need to check freebits because no pointer must exist
                 //  to a block that was free before starting the collection
             }
-            else if (bins == B_PAGE)
+            else if (bins == Bins.B_PAGE)
             {
                 biti = pn * (PAGESIZE >> pool.ShiftBy.Large);
             }
-            else if (bins == B_PAGEPLUS)
+            else if (bins == Bins.B_PAGEPLUS)
             {
                 pn -= pool.bPageOffsets[pn];
                 biti = pn * (PAGESIZE >> pool.ShiftBy.Large);
             }
-            else // bins == B_FREE
+            else // bins == Bins.B_FREE
             {
-                assert(bins == B_FREE);
+                assert(bins == Bins.B_FREE);
                 return IsMarked.no;
             }
             return pool.mark.test(biti) ? IsMarked.yes : IsMarked.no;
@@ -3262,8 +3259,11 @@ Lmark:
 
     /* ============================ Parallel scanning =============================== */
     version (COLLECT_PARALLEL):
-    import core.sync.event;
+
     import core.atomic;
+    import core.cpuid;
+    import core.sync.event;
+
     private: // disable invariants for background threads
 
     static struct ScanThreadData
@@ -3334,7 +3334,6 @@ Lmark:
 
     int maxParallelThreads() nothrow
     {
-        import core.cpuid;
         auto threads = threadsPerCPU();
 
         if (threads == 0)
@@ -3512,7 +3511,7 @@ struct Pool
     GCBits is_pointer;  // precise GC only: per-word, not per-block like the rest of them (SmallObjectPool only)
     size_t npages;
     size_t freepages;     // The number of pages not in use.
-    ubyte* pagetable;
+    Bins* pagetable;
 
     bool isLargeObject;
 
@@ -3541,7 +3540,7 @@ struct Pool
     enum PageRecovered = uint.max;
 
     // first of chain of pages to recover (SmallObjectPool only)
-    uint[B_NUMSMALL] recoverPageFirst;
+    uint[Bins.B_NUMSMALL] recoverPageFirst;
 
     // precise GC: TypeInfo.rtInfo for allocation (LargeObjectPool only)
     immutable(size_t)** rtinfo;
@@ -3611,7 +3610,7 @@ struct Pool
         noscan.alloc(nbits);
         appendable.alloc(nbits);
 
-        pagetable = cast(ubyte*)cstdlib.malloc(npages);
+        pagetable = cast(Bins*)cstdlib.malloc(npages * Bins.sizeof);
         if (!pagetable)
             onOutOfMemoryErrorNoGC();
 
@@ -3635,7 +3634,7 @@ struct Pool
             }
         }
 
-        memset(pagetable, B_FREE, npages);
+        memset(pagetable, Bins.B_FREE, npages);
 
         this.npages = npages;
         this.freepages = npages;
@@ -3852,7 +3851,7 @@ struct Pool
     }
 
     public
-    @property bool isFree() const pure nothrow
+    @property bool isFree() const scope @safe pure nothrow @nogc
     {
         return npages == freepages;
     }
@@ -3883,10 +3882,10 @@ struct Pool
     {
         size_t offset = cast(size_t)(p - baseAddr);
         size_t pn = offset / PAGESIZE;
-        Bins   bin = cast(Bins)pagetable[pn];
+        Bins   bin = pagetable[pn];
 
         // Adjust bit to be at start of allocated memory block
-        if (bin < B_NUMSMALL)
+        if (bin < Bins.B_NUMSMALL)
         {
             auto baseOff = baseOffset(offset, bin);
             const biti = baseOff >> Pool.ShiftBy.Small;
@@ -3894,11 +3893,11 @@ struct Pool
                 return null;
             return baseAddr + baseOff;
         }
-        if (bin == B_PAGE)
+        if (bin == Bins.B_PAGE)
         {
             return baseAddr + (offset & (offset.max ^ (PAGESIZE-1)));
         }
-        if (bin == B_PAGEPLUS)
+        if (bin == Bins.B_PAGEPLUS)
         {
             size_t pageOffset = bPageOffsets[pn];
             offset -= pageOffset * PAGESIZE;
@@ -3907,7 +3906,7 @@ struct Pool
             return baseAddr + (offset & (offset.max ^ (PAGESIZE-1)));
         }
         // we are in a B_FREE page
-        assert(bin == B_FREE);
+        assert(bin == Bins.B_FREE);
         return null;
     }
 
@@ -3944,8 +3943,8 @@ struct Pool
         {
             for (size_t i = 0; i < npages; i++)
             {
-                Bins bin = cast(Bins)pagetable[i];
-                assert(bin < B_MAX);
+                Bins bin = pagetable[i];
+                assert(bin < Bins.B_MAX);
             }
         }
     }
@@ -4053,19 +4052,19 @@ struct LargeObjectPool
             uint np = bPageOffsets[n];
             assert(np > 0 && np <= npages - n);
 
-            if (pagetable[n] == B_PAGE)
+            if (pagetable[n] == Bins.B_PAGE)
             {
                 for (uint p = 1; p < np; p++)
                 {
-                    assert(pagetable[n + p] == B_PAGEPLUS);
+                    assert(pagetable[n + p] == Bins.B_PAGEPLUS);
                     assert(bPageOffsets[n + p] == p);
                 }
             }
-            else if (pagetable[n] == B_FREE)
+            else if (pagetable[n] == Bins.B_FREE)
             {
                 for (uint p = 1; p < np; p++)
                 {
-                    assert(pagetable[n + p] == B_FREE);
+                    assert(pagetable[n + p] == Bins.B_FREE);
                 }
                 assert(bPageOffsets[n + np - 1] == np);
             }
@@ -4086,17 +4085,17 @@ struct LargeObjectPool
 
         //debug(PRINTF) printf("Pool::allocPages(n = %d)\n", n);
         size_t largest = 0;
-        if (pagetable[searchStart] == B_PAGEPLUS)
+        if (pagetable[searchStart] == Bins.B_PAGEPLUS)
         {
             searchStart -= bPageOffsets[searchStart]; // jump to B_PAGE
             searchStart += bPageOffsets[searchStart];
         }
-        while (searchStart < npages && pagetable[searchStart] == B_PAGE)
+        while (searchStart < npages && pagetable[searchStart] == Bins.B_PAGE)
             searchStart += bPageOffsets[searchStart];
 
         for (size_t i = searchStart; i < npages; )
         {
-            assert(pagetable[i] == B_FREE);
+            assert(pagetable[i] == Bins.B_FREE);
 
             auto p = bPageOffsets[i];
             if (p > n)
@@ -4107,11 +4106,11 @@ struct LargeObjectPool
             if (p == n)
             {
             L_found:
-                pagetable[i] = B_PAGE;
+                pagetable[i] = Bins.B_PAGE;
                 bPageOffsets[i] = cast(uint) n;
                 if (n > 1)
                 {
-                    memset(&pagetable[i + 1], B_PAGEPLUS, n - 1);
+                    memset(&pagetable[i + 1], Bins.B_PAGEPLUS, n - 1);
                     for (auto offset = 1; offset < n; offset++)
                         bPageOffsets[i + offset] = cast(uint) offset;
                 }
@@ -4122,7 +4121,7 @@ struct LargeObjectPool
                 largest = p;
 
             i += p;
-            while (i < npages && pagetable[i] == B_PAGE)
+            while (i < npages && pagetable[i] == Bins.B_PAGE)
             {
                 // we have the size information, so we skip a whole bunch of pages.
                 i += bPageOffsets[i];
@@ -4145,8 +4144,8 @@ struct LargeObjectPool
 
         for (size_t i = pagenum; i < npages + pagenum; i++)
         {
-            assert(pagetable[i] < B_FREE);
-            pagetable[i] = B_FREE;
+            assert(pagetable[i] < Bins.B_FREE);
+            pagetable[i] = Bins.B_FREE;
         }
         freepages += npages;
         largestFree = freepages; // invalidate
@@ -4157,8 +4156,8 @@ struct LargeObjectPool
      */
     void setFreePageOffsets(size_t page, size_t num) nothrow @nogc
     {
-        assert(pagetable[page] == B_FREE);
-        assert(pagetable[page + num - 1] == B_FREE);
+        assert(pagetable[page] == Bins.B_FREE);
+        assert(pagetable[page + num - 1] == Bins.B_FREE);
         bPageOffsets[page] = cast(uint)num;
         if (num > 1)
             bPageOffsets[page + num - 1] = cast(uint)num;
@@ -4168,7 +4167,7 @@ struct LargeObjectPool
     {
         static if (bwd)
         {
-            if (page > 0 && pagetable[page - 1] == B_FREE)
+            if (page > 0 && pagetable[page - 1] == Bins.B_FREE)
             {
                 auto sz = bPageOffsets[page - 1];
                 page -= sz;
@@ -4177,7 +4176,7 @@ struct LargeObjectPool
         }
         static if (fwd)
         {
-            if (page + num < npages && pagetable[page + num] == B_FREE)
+            if (page + num < npages && pagetable[page + num] == Bins.B_FREE)
                 num += bPageOffsets[page + num];
         }
         setFreePageOffsets(page, num);
@@ -4197,8 +4196,8 @@ struct LargeObjectPool
         if (cast(size_t)p & (PAGESIZE - 1)) // check for interior pointer
             return 0;
         size_t pagenum = pagenumOf(p);
-        Bins bin = cast(Bins)pagetable[pagenum];
-        if (bin != B_PAGE)
+        Bins bin = pagetable[pagenum];
+        if (bin != Bins.B_PAGE)
             return 0;
         return bPageOffsets[pagenum];
     }
@@ -4208,7 +4207,7 @@ struct LargeObjectPool
     */
     size_t getSize(size_t pn) const nothrow @nogc
     {
-        assert(pagetable[pn] == B_PAGE);
+        assert(pagetable[pn] == Bins.B_PAGE);
         return cast(size_t) bPageOffsets[pn] * PAGESIZE;
     }
 
@@ -4221,11 +4220,11 @@ struct LargeObjectPool
 
         size_t offset = cast(size_t)(p - baseAddr);
         size_t pn = offset / PAGESIZE;
-        Bins bin = cast(Bins)pagetable[pn];
+        Bins bin = pagetable[pn];
 
-        if (bin == B_PAGEPLUS)
+        if (bin == Bins.B_PAGEPLUS)
             pn -= bPageOffsets[pn];
-        else if (bin != B_PAGE)
+        else if (bin != Bins.B_PAGE)
             return info;           // no info for free pages
 
         info.base = baseAddr + pn * PAGESIZE;
@@ -4238,8 +4237,8 @@ struct LargeObjectPool
     {
         foreach (pn; 0 .. npages)
         {
-            Bins bin = cast(Bins)pagetable[pn];
-            if (bin > B_PAGE)
+            Bins bin = pagetable[pn];
+            if (bin > Bins.B_PAGE)
                 continue;
             size_t biti = pn;
 
@@ -4265,7 +4264,7 @@ struct LargeObjectPool
 
             size_t n = 1;
             for (; pn + n < npages; ++n)
-                if (pagetable[pn + n] != B_PAGEPLUS)
+                if (pagetable[pn + n] != Bins.B_PAGEPLUS)
                     break;
             debug (MEMSTOMP) memset(baseAddr + pn * PAGESIZE, 0xF3, n * PAGESIZE);
             freePages(pn, n);
@@ -4285,7 +4284,7 @@ struct SmallObjectPool
     {
         //base.Invariant();
         uint cntRecover = 0;
-        foreach (Bins bin; 0 .. B_NUMSMALL)
+        foreach (Bins bin; Bins.B_16 .. Bins.B_NUMSMALL)
         {
             for (auto pn = recoverPageFirst[bin]; pn < npages; pn = binPageChain[pn])
             {
@@ -4296,7 +4295,7 @@ struct SmallObjectPool
         uint cntFree = 0;
         for (auto pn = searchStart; pn < npages; pn = binPageChain[pn])
         {
-            assert(pagetable[pn] == B_FREE);
+            assert(pagetable[pn] == Bins.B_FREE);
             cntFree++;
         }
         assert(cntFree == freepages);
@@ -4315,8 +4314,8 @@ struct SmallObjectPool
     do
     {
         size_t pagenum = pagenumOf(p);
-        Bins bin = cast(Bins)pagetable[pagenum];
-        assert(bin < B_PAGE);
+        Bins bin = pagetable[pagenum];
+        assert(bin < Bins.B_PAGE);
         if (p != cast(void*)baseOffset(cast(size_t)p, bin)) // check for interior pointer
             return 0;
         const biti = cast(size_t)(p - baseAddr) >> ShiftBy.Small;
@@ -4330,9 +4329,9 @@ struct SmallObjectPool
         BlkInfo info;
         size_t offset = cast(size_t)(p - baseAddr);
         size_t pn = offset / PAGESIZE;
-        Bins   bin = cast(Bins)pagetable[pn];
+        Bins   bin = pagetable[pn];
 
-        if (bin >= B_PAGE)
+        if (bin >= Bins.B_PAGE)
             return info;
 
         auto base = cast(void*)baseOffset(cast(size_t)p, bin);
@@ -4352,8 +4351,8 @@ struct SmallObjectPool
     {
         foreach (pn; 0 .. npages)
         {
-            Bins bin = cast(Bins)pagetable[pn];
-            if (bin >= B_PAGE)
+            Bins bin = pagetable[pn];
+            if (bin >= Bins.B_PAGE)
                 continue;
 
             immutable size = binsize[bin];
@@ -4404,13 +4403,13 @@ struct SmallObjectPool
         if (searchStart >= npages)
             return null;
 
-        assert(pagetable[searchStart] == B_FREE);
+        assert(pagetable[searchStart] == Bins.B_FREE);
 
     L1:
         size_t pn = searchStart;
         searchStart = binPageChain[searchStart];
         binPageChain[pn] = Pool.PageRecovered;
-        pagetable[pn] = cast(ubyte)bin;
+        pagetable[pn] = bin;
         freepages--;
 
         // Convert page to free list
@@ -4537,7 +4536,7 @@ debug(PRINTF) void printFreeInfo(Pool* pool) nothrow
 {
     uint nReallyFree;
     foreach (i; 0..pool.npages) {
-        if (pool.pagetable[i] >= B_FREE) nReallyFree++;
+        if (pool.pagetable[i] >= Bins.B_FREE) nReallyFree++;
     }
 
     printf("Pool %p:  %d really free, %d supposedly free\n", pool, nReallyFree, pool.freepages);
@@ -4770,7 +4769,7 @@ debug (LOGGING)
                 size_t offset = cast(size_t)(p - pool.baseAddr);
                 size_t biti;
                 size_t pn = offset / PAGESIZE;
-                Bins bin = cast(Bins)pool.pagetable[pn];
+                Bins bin = pool.pagetable[pn];
                 biti = (offset & (PAGESIZE - 1)) >> pool.shiftBy;
                 debug(PRINTF) printf("\tbin = %d, offset = x%x, biti = x%x\n", bin, offset, biti);
             }
@@ -4921,7 +4920,7 @@ unittest
     assert(p + (260 << 20) == q);
     assert(q + (65 << 20) == r);
     GC.free(q);
-    // should trigger "assert(bin == B_FREE);" in mark due to dangling pointer q:
+    // should trigger "assert(bin == Bins.B_FREE);" in mark due to dangling pointer q:
     GC.collect();
     // should trigger "break;" in extendNoSync:
     size_t sz = GC.extend(p, 64 << 20, 66 << 20); // trigger size after p large enough (but limited)
diff --git a/libphobos/libdruntime/core/internal/gc/pooltable.d b/libphobos/libdruntime/core/internal/gc/pooltable.d
index 5924f9c1a55..096633825a2 100644
--- a/libphobos/libdruntime/core/internal/gc/pooltable.d
+++ b/libphobos/libdruntime/core/internal/gc/pooltable.d
@@ -13,15 +13,14 @@ struct PoolTable(Pool)
 {
     import core.stdc.string : memmove;
 
-nothrow:
-    void Dtor()
+    void Dtor() nothrow @nogc
     {
         cstdlib.free(pools);
         pools = null;
         npools = 0;
     }
 
-    bool insert(Pool* pool)
+    bool insert(Pool* pool) nothrow @nogc
     {
         auto newpools = cast(Pool **)cstdlib.realloc(pools, (npools + 1) * pools[0].sizeof);
         if (!newpools)
@@ -51,25 +50,31 @@ nothrow:
         return true;
     }
 
-    @property size_t length() pure const
+    @property size_t length() const scope @safe pure nothrow @nogc
     {
         return npools;
     }
 
-    ref inout(Pool*) opIndex(size_t idx) inout pure
+    ref inout(Pool*) opIndex(size_t idx) inout return @trusted pure nothrow @nogc
     in { assert(idx < length); }
     do
     {
         return pools[idx];
     }
 
-    inout(Pool*)[] opSlice(size_t a, size_t b) inout pure
+    inout(Pool*)[] opSlice(size_t a, size_t b) inout return @trusted pure nothrow @nogc
     in { assert(a <= length && b <= length); }
     do
     {
         return pools[a .. b];
     }
 
+    /// Returns: A slice over all pools in this `PoolTable`
+    inout(Pool*)[] opSlice() inout return @trusted pure nothrow @nogc
+    {
+        return this.pools[0 .. this.length];
+    }
+
     alias opDollar = length;
 
     /**
@@ -77,7 +82,7 @@ nothrow:
      * Return null if not in a Pool.
      * Assume pooltable[] is sorted.
      */
-    Pool *findPool(void *p) nothrow
+    Pool *findPool(void *p) nothrow @nogc
     {
         if (p >= minAddr && p < maxAddr)
         {
@@ -109,7 +114,7 @@ nothrow:
     }
 
     // semi-stable partition, returns right half for which pred is false
-    Pool*[] minimize() pure
+    Pool*[] minimize() pure nothrow @nogc
     {
         static void swap(ref Pool* a, ref Pool* b)
         {
@@ -151,7 +156,7 @@ nothrow:
         return pools[npools .. len];
     }
 
-    void Invariant() const
+    void Invariant() const nothrow @nogc
     {
         if (!npools) return;
 
@@ -165,8 +170,8 @@ nothrow:
         assert(_maxAddr == pools[npools - 1].topAddr);
     }
 
-    @property const(void)* minAddr() pure const { return _minAddr; }
-    @property const(void)* maxAddr() pure const { return _maxAddr; }
+    @property const(void)* minAddr() const @safe pure nothrow @nogc { return _minAddr; }
+    @property const(void)* maxAddr() const @safe pure nothrow @nogc { return _maxAddr; }
 
 package:
     Pool** pools;
@@ -184,7 +189,7 @@ unittest
     {
         byte* baseAddr, topAddr;
         size_t freepages, npages, ptIndex;
-        @property bool isFree() const pure nothrow { return freepages == npages; }
+        @property bool isFree() const scope pure nothrow @nogc { return freepages == npages; }
     }
     PoolTable!MockPool pooltable;
 
diff --git a/libphobos/libdruntime/core/internal/gc/proxy.d b/libphobos/libdruntime/core/internal/gc/proxy.d
index 2c89472a558..695ef061a81 100644
--- a/libphobos/libdruntime/core/internal/gc/proxy.d
+++ b/libphobos/libdruntime/core/internal/gc/proxy.d
@@ -209,12 +209,12 @@ extern (C)
         return instance.query( p );
     }
 
-    core.memory.GC.Stats gc_stats() nothrow
+    core.memory.GC.Stats gc_stats() @safe nothrow @nogc
     {
         return instance.stats();
     }
 
-    core.memory.GC.ProfileStats gc_profileStats() nothrow @safe
+    core.memory.GC.ProfileStats gc_profileStats() @safe nothrow @nogc
     {
         return instance.profileStats();
     }
diff --git a/libphobos/libdruntime/core/memory.d b/libphobos/libdruntime/core/memory.d
index 6ba569a241c..f25ba6f1d46 100644
--- a/libphobos/libdruntime/core/memory.d
+++ b/libphobos/libdruntime/core/memory.d
@@ -133,7 +133,7 @@ private
     }
 
     extern (C) BlkInfo_ gc_query(return scope void* p) pure nothrow;
-    extern (C) GC.Stats gc_stats ( ) nothrow @nogc;
+    extern (C) GC.Stats gc_stats ( ) @safe nothrow @nogc;
     extern (C) GC.ProfileStats gc_profileStats ( ) nothrow @nogc @safe;
 }
 
@@ -766,7 +766,7 @@ extern(D):
      * Returns runtime stats for currently active GC implementation
      * See `core.memory.GC.Stats` for list of available metrics.
      */
-    static Stats stats() nothrow
+    static Stats stats() @safe nothrow @nogc
     {
         return gc_stats();
     }
diff --git a/libphobos/libdruntime/core/stdcpp/string.d b/libphobos/libdruntime/core/stdcpp/string.d
index 1cdb0f40952..dfec1ec9f7e 100644
--- a/libphobos/libdruntime/core/stdcpp/string.d
+++ b/libphobos/libdruntime/core/stdcpp/string.d
@@ -343,7 +343,7 @@ extern(D):
         ///
         inout(T)* data() inout @safe                                        { return _Get_data()._Myptr; }
         ///
-        inout(T)[] as_array() inout nothrow @trusted                        { return _Get_data()._Myptr[0 .. _Get_data()._Mysize]; }
+        inout(T)[] as_array() return scope inout nothrow @trusted           { return _Get_data()._Myptr[0 .. _Get_data()._Mysize]; }
         ///
         ref inout(T) at(size_type i) inout nothrow @trusted                 { return _Get_data()._Myptr[0 .. _Get_data()._Mysize][i]; }
 
@@ -1920,7 +1920,7 @@ extern(D):
         ///
         inout(T)* data() inout @safe                                        { return __get_pointer(); }
         ///
-        inout(T)[] as_array() inout nothrow @trusted                        { return __get_pointer()[0 .. size()]; }
+        inout(T)[] as_array() return scope inout nothrow @trusted           { return __get_pointer()[0 .. size()]; }
         ///
         ref inout(T) at(size_type i) inout nothrow @trusted                 { return __get_pointer()[0 .. size()][i]; }
 
@@ -2497,8 +2497,8 @@ extern(C++, (StdNamespace)):
     extern(D) @safe @nogc:
         pragma(inline, true)
         {
-            ref inout(Alloc) _Getal() inout pure nothrow { return _Mypair._Myval1; }
-            ref inout(ValTy) _Get_data() inout pure nothrow { return _Mypair._Myval2; }
+            ref inout(Alloc) _Getal() return inout pure nothrow { return _Mypair._Myval1; }
+            ref inout(ValTy) _Get_data() return inout pure nothrow { return _Mypair._Myval2; }
         }
 
         void _Orphan_all() nothrow { _Get_data._Base._Orphan_all(); }
diff --git a/libphobos/libdruntime/core/sys/posix/sys/stat.d b/libphobos/libdruntime/core/sys/posix/sys/stat.d
index 22f4df66455..1fb4e44cbbf 100644
--- a/libphobos/libdruntime/core/sys/posix/sys/stat.d
+++ b/libphobos/libdruntime/core/sys/posix/sys/stat.d
@@ -388,50 +388,93 @@ version (linux)
     {
         struct stat_t
         {
-            c_ulong     st_dev;
-            ino_t       st_ino;
+            dev_t       st_dev;
+            static if (!__USE_FILE_OFFSET64)
+            {
+                ushort  __pad1;
+                ino_t   st_ino;
+            }
+            else
+                ino_t   st_ino;
             mode_t      st_mode;
             nlink_t     st_nlink;
             uid_t       st_uid;
             gid_t       st_gid;
-            c_ulong     st_rdev;
+            dev_t       st_rdev;
+            ushort      __pad2;
             off_t       st_size;
-            c_ulong     st_blksize;
-            c_ulong     st_blocks;
-            c_ulong     st_atime;
-            c_ulong     st_atime_nsec;
-            c_ulong     st_mtime;
-            c_ulong     st_mtime_nsec;
-            c_ulong     st_ctime;
-            c_ulong     st_ctime_nsec;
+            blksize_t   st_blksize;
+            blkcnt_t    st_blocks;
+            static if (_DEFAULT_SOURCE || _XOPEN_SOURCE >= 700)
+            {
+                timespec    st_atim;
+                timespec    st_mtim;
+                timespec    st_ctim;
+                extern(D) @safe @property inout pure nothrow
+                {
+                    ref inout(time_t) st_atime() return { return st_atim.tv_sec; }
+                    ref inout(time_t) st_mtime() return { return st_mtim.tv_sec; }
+                    ref inout(time_t) st_ctime() return { return st_ctim.tv_sec; }
+                }
+            }
+            else
+            {
+                time_t      st_atime;
+                c_ulong     st_atimensec;
+                time_t      st_mtime;
+                c_ulong     st_mtimensec;
+                time_t      st_ctime;
+                c_ulong     st_ctimensec;
+            }
             c_ulong     __unused4;
             c_ulong     __unused5;
         }
+        static if (__USE_FILE_OFFSET64)
+            static assert(stat_t.sizeof == 104);
+        else
+            static assert(stat_t.sizeof == 88);
     }
     else version (PPC64)
     {
         struct stat_t
         {
-            c_ulong     st_dev;
+            dev_t       st_dev;
             ino_t       st_ino;
             nlink_t     st_nlink;
             mode_t      st_mode;
             uid_t       st_uid;
             gid_t       st_gid;
-            c_ulong     st_rdev;
+            int         __pad2;
+            dev_t       st_rdev;
             off_t       st_size;
-            c_ulong     st_blksize;
-            c_ulong     st_blocks;
-            c_ulong     st_atime;
-            c_ulong     st_atime_nsec;
-            c_ulong     st_mtime;
-            c_ulong     st_mtime_nsec;
-            c_ulong     st_ctime;
-            c_ulong     st_ctime_nsec;
+            blksize_t   st_blksize;
+            blkcnt_t    st_blocks;
+            static if (_DEFAULT_SOURCE || _XOPEN_SOURCE >= 700)
+            {
+                timespec    st_atim;
+                timespec    st_mtim;
+                timespec    st_ctim;
+                extern(D) @safe @property inout pure nothrow
+                {
+                    ref inout(time_t) st_atime() return { return st_atim.tv_sec; }
+                    ref inout(time_t) st_mtime() return { return st_mtim.tv_sec; }
+                    ref inout(time_t) st_ctime() return { return st_ctim.tv_sec; }
+                }
+            }
+            else
+            {
+                time_t      st_atime;
+                c_ulong     st_atimensec;
+                time_t      st_mtime;
+                c_ulong     st_mtimensec;
+                time_t      st_ctime;
+                c_ulong     st_ctimensec;
+            }
             c_ulong     __unused4;
             c_ulong     __unused5;
             c_ulong     __unused6;
         }
+        static assert(stat_t.sizeof == 144);
     }
     else version (RISCV_Any)
     {
diff --git a/libphobos/libdruntime/core/time.d b/libphobos/libdruntime/core/time.d
index 0ddf62f478c..91f218e27fb 100644
--- a/libphobos/libdruntime/core/time.d
+++ b/libphobos/libdruntime/core/time.d
@@ -496,6 +496,81 @@ assert(std.datetime.Date(2010, 9, 7) - std.datetime.Date(2010, 10, 3) ==
  +/
 struct Duration
 {
+    /++
+        Converts this `Duration` to a `string`.
+
+        The string is meant to be human readable, not machine parseable (e.g.
+        whether there is an `'s'` on the end of the unit name usually depends on
+        whether it's plural or not, and empty units are not included unless the
+        Duration is `zero`). Any code needing a specific string format should
+        use `total` or `split` to get the units needed to create the desired
+        string format and create the string itself.
+
+        The format returned by toString may or may not change in the future.
+
+        Params:
+          sink = A sink object, expected to be a delegate or aggregate
+                 implementing `opCall` that accepts a `scope const(char)[]`
+                 as argument.
+      +/
+    void toString (SinkT) (scope SinkT sink) const scope
+    {
+        static immutable units = [
+            "weeks", "days", "hours", "minutes", "seconds", "msecs", "usecs"
+        ];
+
+        static void appListSep(SinkT sink, uint pos, bool last)
+        {
+            if (pos == 0)
+                return;
+            if (!last)
+                sink(", ");
+            else
+                sink(pos == 1 ? " and " : ", and ");
+        }
+
+        static void appUnitVal(string units)(SinkT sink, long val)
+        {
+            immutable plural = val != 1;
+            string unit;
+            static if (units == "seconds")
+                unit = plural ? "secs" : "sec";
+            else static if (units == "msecs")
+                unit = "ms";
+            else static if (units == "usecs")
+                unit = "μs";
+            else
+                unit = plural ? units : units[0 .. $-1];
+            sink(signedToTempString(val));
+            sink(" ");
+            sink(unit);
+        }
+
+        if (_hnsecs == 0)
+        {
+            sink("0 hnsecs");
+            return;
+        }
+
+        long hnsecs = _hnsecs;
+        uint pos;
+        static foreach (unit; units)
+        {
+            if (auto val = splitUnitsFromHNSecs!unit(hnsecs))
+            {
+                appListSep(sink, pos++, hnsecs == 0);
+                appUnitVal!unit(sink, val);
+            }
+            if (hnsecs == 0)
+                return;
+        }
+        if (hnsecs != 0)
+        {
+            appListSep(sink, pos++, true);
+            appUnitVal!"hnsecs"(sink, hnsecs);
+        }
+    }
+
 @safe pure:
 
 public:
@@ -1539,71 +1614,12 @@ public:
         }
     }
 
-
-    /++
-        Converts this `Duration` to a `string`.
-
-        The string is meant to be human readable, not machine parseable (e.g.
-        whether there is an `'s'` on the end of the unit name usually depends on
-        whether it's plural or not, and empty units are not included unless the
-        Duration is `zero`). Any code needing a specific string format should
-        use `total` or `split` to get the units needed to create the desired
-        string format and create the string itself.
-
-        The format returned by toString may or may not change in the future.
-      +/
-    string toString() const nothrow pure @safe
+    /// Ditto
+    string toString() const scope nothrow
     {
-        static void appListSep(ref string res, uint pos, bool last)
-        {
-            if (pos == 0)
-                return;
-            if (!last)
-                res ~= ", ";
-            else
-                res ~= pos == 1 ? " and " : ", and ";
-        }
-
-        static void appUnitVal(string units)(ref string res, long val)
-        {
-            immutable plural = val != 1;
-            string unit;
-            static if (units == "seconds")
-                unit = plural ? "secs" : "sec";
-            else static if (units == "msecs")
-                unit = "ms";
-            else static if (units == "usecs")
-                unit = "μs";
-            else
-                unit = plural ? units : units[0 .. $-1];
-            res ~= signedToTempString(val);
-            res ~= " ";
-            res ~= unit;
-        }
-
-        if (_hnsecs == 0)
-            return "0 hnsecs";
-
-        template TT(T...) { alias T TT; }
-        alias units = TT!("weeks", "days", "hours", "minutes", "seconds", "msecs", "usecs");
-
-        long hnsecs = _hnsecs; string res; uint pos;
-        foreach (unit; units)
-        {
-            if (auto val = splitUnitsFromHNSecs!unit(hnsecs))
-            {
-                appListSep(res, pos++, hnsecs == 0);
-                appUnitVal!unit(res, val);
-            }
-            if (hnsecs == 0)
-                break;
-        }
-        if (hnsecs != 0)
-        {
-            appListSep(res, pos++, true);
-            appUnitVal!"hnsecs"(res, hnsecs);
-        }
-        return res;
+        string result;
+        this.toString((in char[] data) { result ~= data; });
+        return result;
     }
 
     ///
@@ -1731,6 +1747,20 @@ unittest
     assert(myTime == 123.msecs);
 }
 
+// Ensure `toString` doesn't allocate if the sink doesn't
+version (CoreUnittest) @safe pure nothrow @nogc unittest
+{
+    char[256] buffer; size_t len;
+    scope sink = (in char[] data) {
+        assert(data.length + len <= buffer.length);
+        buffer[len .. len + data.length] = data[];
+        len += data.length;
+    };
+    auto dur = Duration(-12_096_020_900_003);
+    dur.toString(sink);
+    assert(buffer[0 .. len] == "-2 weeks, -2 secs, -90 ms, and -3 hnsecs");
+}
+
 /++
     Converts a $(D TickDuration) to the given units as either an integral
     value or a floating point value.
diff --git a/libphobos/libdruntime/object.d b/libphobos/libdruntime/object.d
index cf7cf967aa6..56a2efe735a 100644
--- a/libphobos/libdruntime/object.d
+++ b/libphobos/libdruntime/object.d
@@ -2649,13 +2649,18 @@ class Throwable : Object
 
     /**
      * Get the message describing the error.
-     * Base behavior is to return the `Throwable.msg` field.
-     * Override to return some other error message.
+     *
+     * This getter is an alternative way to access the Exception's message,
+     * with the added advantage of being override-able in subclasses.
+     * Subclasses are hence free to do their own memory managements without
+     * being tied to the requirement of providing a `string` in a field.
+     *
+     * The default behavior is to return the `Throwable.msg` field.
      *
      * Returns:
-     *  Error message
+     *  A message representing the cause of the `Throwable`
      */
-    @__future const(char)[] message() const
+    @__future const(char)[] message() const @safe nothrow
     {
         return this.msg;
     }
diff --git a/libphobos/src/MERGE b/libphobos/src/MERGE
index b5b939f41b3..e15541e181d 100644
--- a/libphobos/src/MERGE
+++ b/libphobos/src/MERGE
@@ -1,4 +1,4 @@
-1a3e80ec25afab6123cdcfe20186f36f006b68bb
+41aaf8c2636df0e2e3ad39933b321d2b4cd231fa
 
 The first line of this file holds the git revision number of the last
 merge done from the dlang/phobos repository.
diff --git a/libphobos/src/std/file.d b/libphobos/src/std/file.d
index a99c5170afb..b09b82ab85e 100644
--- a/libphobos/src/std/file.d
+++ b/libphobos/src/std/file.d
@@ -425,10 +425,10 @@ version (Windows) private void[] readImpl(scope const(char)[] name, scope const(
             fileSize = makeUlong(sizeLow, sizeHigh);
         return result;
     }
-    static trustedReadFile(HANDLE hFile, void *lpBuffer, ulong nNumberOfBytesToRead)
+    static trustedReadFile(HANDLE hFile, void *lpBuffer, size_t nNumberOfBytesToRead)
     {
         // Read by chunks of size < 4GB (Windows API limit)
-        ulong totalNumRead = 0;
+        size_t totalNumRead = 0;
         while (totalNumRead != nNumberOfBytesToRead)
         {
             const uint chunkSize = min(nNumberOfBytesToRead - totalNumRead, 0xffff_0000);
diff --git a/libphobos/src/std/getopt.d b/libphobos/src/std/getopt.d
index 482aae6306a..c1c5cd2b36e 100644
--- a/libphobos/src/std/getopt.d
+++ b/libphobos/src/std/getopt.d
@@ -438,7 +438,7 @@ GetoptResult getopt(T...)(ref string[] args, T opts)
 }
 
 ///
-@system unittest
+@safe unittest
 {
     auto args = ["prog", "--foo", "-b"];
 
@@ -1646,11 +1646,13 @@ Params:
     text = The text to printed at the beginning of the help output.
     opt = The `Option` extracted from the `getopt` parameter.
 */
-void defaultGetoptPrinter(string text, Option[] opt)
+void defaultGetoptPrinter(string text, Option[] opt) @safe
 {
     import std.stdio : stdout;
+    // stdout global __gshared is trusted with a locked text writer
+    auto w = (() @trusted => stdout.lockingTextWriter())();
 
-    defaultGetoptFormatter(stdout.lockingTextWriter(), text, opt);
+    defaultGetoptFormatter(w, text, opt);
 }
 
 /** This function writes the passed text and `Option` into an output range
diff --git a/libphobos/src/std/range/primitives.d b/libphobos/src/std/range/primitives.d
index c092a9d0946..31f58fa5fa9 100644
--- a/libphobos/src/std/range/primitives.d
+++ b/libphobos/src/std/range/primitives.d
@@ -2055,9 +2055,14 @@ if (isBidirectionalRange!Range)
 }
 
 /**
-   Moves the front of `r` out and returns it. Leaves `r.front` in a
-   destroyable state that does not allocate any resources (usually equal
-   to its `.init` value).
+   Moves the front of `r` out and returns it.
+
+   If `r.front` is a struct with a destructor or copy constructor defined, it
+   is reset to its `.init` value after its value is moved. Otherwise, it is
+   left unchanged.
+
+   In either case, `r.front` is left in a destroyable state that does not
+   allocate any resources.
 */
 ElementType!R moveFront(R)(R r)
 {
diff --git a/libphobos/src/std/sumtype.d b/libphobos/src/std/sumtype.d
index 5e35a6b9cd5..0dd636ea67b 100644
--- a/libphobos/src/std/sumtype.d
+++ b/libphobos/src/std/sumtype.d
@@ -533,15 +533,35 @@ public:
         /**
          * Assigns a value to a `SumType`.
          *
-         * Assigning to a `SumType` is `@system` if any of the
-         * `SumType`'s members contain pointers or references, since
-         * those members may be reachable through external references,
-         * and overwriting them could therefore lead to memory
-         * corruption.
+         * If any of the `SumType`'s members other than the one being assigned
+         * to contain pointers or references, it is possible for the assignment
+         * to cause memory corruption (see the
+         * ["Memory corruption" example](#memory-corruption) below for an
+         * illustration of how). Therefore, such assignments are considered
+         * `@system`.
          *
          * An individual assignment can be `@trusted` if the caller can
-         * guarantee that there are no outstanding references to $(I any)
-         * of the `SumType`'s members when the assignment occurs.
+         * guarantee that there are no outstanding references to any `SumType`
+         * members that contain pointers or references at the time the
+         * assignment occurs.
+         *
+         * Examples:
+         *
+         * $(DIVID memory-corruption, $(H3 Memory corruption))
+         *
+         * This example shows how assignment to a `SumType` can be used to
+         * cause memory corruption in `@system` code. In `@safe` code, the
+         * assignment `s = 123` would not be allowed.
+         *
+         * ---
+         * SumType!(int*, int) s = new int;
+         * s.tryMatch!(
+         *     (ref int* p) {
+         *         s = 123; // overwrites `p`
+         *         return *p; // undefined behavior
+         *     }
+         * );
+         * ---
          */
         ref SumType opAssign(T rhs);
     }
@@ -553,14 +573,35 @@ public:
             /**
              * Assigns a value to a `SumType`.
              *
-             * Assigning to a `SumType` is `@system` if any of the `SumType`'s
-             * $(I other) members contain pointers or references, since those
-             * members may be reachable through external references, and
-             * overwriting them could therefore lead to memory corruption.
+             * If any of the `SumType`'s members other than the one being assigned
+             * to contain pointers or references, it is possible for the assignment
+             * to cause memory corruption (see the
+             * ["Memory corruption" example](#memory-corruption) below for an
+             * illustration of how). Therefore, such assignments are considered
+             * `@system`.
              *
              * An individual assignment can be `@trusted` if the caller can
-             * guarantee that, when the assignment occurs, there are no
-             * outstanding references to any such members.
+             * guarantee that there are no outstanding references to any `SumType`
+             * members that contain pointers or references at the time the
+             * assignment occurs.
+             *
+             * Examples:
+             *
+             * $(DIVID memory-corruption, $(H3 Memory corruption))
+             *
+             * This example shows how assignment to a `SumType` can be used to
+             * cause memory corruption in `@system` code. In `@safe` code, the
+             * assignment `s = 123` would not be allowed.
+             *
+             * ---
+             * SumType!(int*, int) s = new int;
+             * s.tryMatch!(
+             *     (ref int* p) {
+             *         s = 123; // overwrites `p`
+             *         return *p; // undefined behavior
+             *     }
+             * );
+             * ---
              */
             ref SumType opAssign(T rhs)
             {
@@ -1528,7 +1569,27 @@ private enum bool isSumTypeInstance(T) = is(T == SumType!Args, Args...);
 }
 
 /// True if `T` is a [SumType] or implicitly converts to one, otherwise false.
-enum bool isSumType(T) = is(T : SumType!Args, Args...);
+template isSumType(T)
+{
+    static if (is(T : SumType!Args, Args...))
+    {
+        enum isSumType = true;
+    }
+    else static if (is(T == struct) && __traits(getAliasThis, T).length > 0)
+    {
+        // Workaround for https://issues.dlang.org/show_bug.cgi?id=21975
+        import std.traits : ReturnType;
+
+        alias AliasThisType = ReturnType!((T t) =>
+            __traits(getMember, t, __traits(getAliasThis, T)[0])
+        );
+        enum isSumType = .isSumType!AliasThisType;
+    }
+    else
+    {
+        enum isSumType = false;
+    }
+}
 
 ///
 @safe unittest
@@ -1549,6 +1610,25 @@ enum bool isSumType(T) = is(T : SumType!Args, Args...);
     assert(!isSumType!ContainsSumType);
 }
 
+@safe unittest
+{
+    static struct AliasThisVar(T)
+    {
+        SumType!T payload;
+        alias payload this;
+    }
+
+    static struct AliasThisFunc(T)
+    {
+        SumType!T payload;
+        ref get() { return payload; }
+        alias get this;
+    }
+
+    static assert(isSumType!(AliasThisVar!int));
+    static assert(isSumType!(AliasThisFunc!int));
+}
+
 /**
  * Calls a type-appropriate function with the value held in a [SumType].
  *