Add a DiagnosticManager replace error streams in the expression parser.

We want to do a better job presenting errors that occur when evaluating
expressions. Key to this effort is getting away from a model where all
errors are spat out onto a stream where the client has to take or leave
all of them.

To this end, this patch adds a new class, DiagnosticManager, which
contains errors produced by the compiler or by LLDB as an expression
is created. The DiagnosticManager can dump itself to a log as well as
to a string. Clients will (in the future) be able to filter out the
errors they're interested in by ID or present subsets of these errors
to the user.

This patch is not intended to change the *users* of errors - only to
thread DiagnosticManagers to all the places where streams are used. I
also attempt to standardize our use of errors a bit, removing trailing
newlines and making clients omit 'error:', 'warning:' etc. and instead
pass the Severity flag.

The patch is testsuite-neutral, with modifications to one part of the
MI tests because it relied on "error: error:" being erroneously
printed. This patch fixes the MI variable handling and the testcase.

<rdar://problem/22864976>

4 files changed, 106 insertions, 76 deletions

diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetItemInfoHandler.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetItemInfoHandler.cpp
index 2ca367c0cce..19f89f077cd 100644
--- a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetItemInfoHandler.cpp
+++ b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetItemInfoHandler.cpp
@@ -19,6 +19,7 @@
 #include "lldb/Core/Module.h"
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/Value.h"
+#include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/FunctionCaller.h"
 #include "lldb/Expression/UtilityFunction.h"
 #include "lldb/Symbol/ClangASTContext.h"
@@ -132,11 +133,11 @@ AppleGetItemInfoHandler::Detach ()
 // make the function call.
 
 lldb::addr_t
-AppleGetItemInfoHandler::SetupGetItemInfoFunction (Thread &thread, ValueList &get_item_info_arglist)
+AppleGetItemInfoHandler::SetupGetItemInfoFunction(Thread &thread, ValueList &get_item_info_arglist)
 {
-    ExecutionContext exe_ctx (thread.shared_from_this());
-    StreamString errors;
-    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_SYSTEM_RUNTIME));
+    ExecutionContext exe_ctx(thread.shared_from_this());
+    DiagnosticManager diagnostics;
+    Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SYSTEM_RUNTIME));
     lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
     FunctionCaller *get_item_info_caller = nullptr;
 
@@ -161,11 +162,14 @@ AppleGetItemInfoHandler::SetupGetItemInfoFunction (Thread &thread, ValueList &ge
                         log->Printf ("Failed to get utility function: %s.", error.AsCString());
                     return args_addr;
                 }
-                
-                if (!m_get_item_info_impl_code->Install(errors, exe_ctx))
+
+                if (!m_get_item_info_impl_code->Install(diagnostics, exe_ctx))
                 {
                     if (log)
-                        log->Printf ("Failed to install get-item-info introspection: %s.", errors.GetData());
+                    {
+                        log->Printf("Failed to install get-item-info introspection.");
+                        diagnostics.Dump(log);
+                    }
                     m_get_item_info_impl_code.reset();
                     return args_addr;
                 }
@@ -174,7 +178,6 @@ AppleGetItemInfoHandler::SetupGetItemInfoFunction (Thread &thread, ValueList &ge
             {
                 if (log)
                     log->Printf("No get-item-info introspection code found.");
-                errors.Printf ("No get-item-info introspection code found.");
                 return LLDB_INVALID_ADDRESS;
             }
 
@@ -207,20 +210,24 @@ AppleGetItemInfoHandler::SetupGetItemInfoFunction (Thread &thread, ValueList &ge
             }
         }
     }
-    
-    errors.Clear();
-    
+
+    diagnostics.Clear();
+
     // Now write down the argument values for this particular call.  This looks like it might be a race condition
     // if other threads were calling into here, but actually it isn't because we allocate a new args structure for
     // this call by passing args_addr = LLDB_INVALID_ADDRESS...
 
-    if (!get_item_info_caller->WriteFunctionArguments (exe_ctx, args_addr, get_item_info_arglist, errors))
+    if (!get_item_info_caller->WriteFunctionArguments(exe_ctx, args_addr, get_item_info_arglist, diagnostics))
     {
         if (log)
-            log->Printf ("Error writing get-item-info function arguments: \"%s\".", errors.GetData());
+        {
+            log->Printf("Error writing get-item-info function arguments.");
+            diagnostics.Dump(log);
+        }
+
         return args_addr;
     }
-        
+
     return args_addr;
 }
 
@@ -322,12 +329,12 @@ AppleGetItemInfoHandler::GetItemInfo (Thread &thread, uint64_t item, addr_t page
     page_to_free_size_value.GetScalar() = page_to_free_size;
     argument_values.PushValue (page_to_free_size_value);
 
-    addr_t args_addr = SetupGetItemInfoFunction (thread, argument_values);
+    addr_t args_addr = SetupGetItemInfoFunction(thread, argument_values);
 
-    StreamString errors;
+    DiagnosticManager diagnostics;
     ExecutionContext exe_ctx;
     EvaluateExpressionOptions options;
-    options.SetUnwindOnError (true);
+    options.SetUnwindOnError(true);
     options.SetIgnoreBreakpoints (true);
     options.SetStopOthers (true);
     options.SetTimeoutUsec(500000);
@@ -351,8 +358,8 @@ AppleGetItemInfoHandler::GetItemInfo (Thread &thread, uint64_t item, addr_t page
         error.SetErrorString("Could not retrieve function caller for __introspection_dispatch_queue_item_get_info.");
         return return_value;
     }
-    
-    func_call_ret =  func_caller->ExecuteFunction (exe_ctx, &args_addr, options, errors, results);
+
+    func_call_ret = func_caller->ExecuteFunction(exe_ctx, &args_addr, options, diagnostics, results);
     if (func_call_ret != eExpressionCompleted || !error.Success())
     {
         if (log)
diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetPendingItemsHandler.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetPendingItemsHandler.cpp
index 97699878f5e..cda7264d17b 100644
--- a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetPendingItemsHandler.cpp
+++ b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetPendingItemsHandler.cpp
@@ -19,6 +19,7 @@
 #include "lldb/Core/Module.h"
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/Value.h"
+#include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/FunctionCaller.h"
 #include "lldb/Expression/UtilityFunction.h"
 #include "lldb/Symbol/ClangASTContext.h"
@@ -136,14 +137,14 @@ AppleGetPendingItemsHandler::Detach ()
 // make the function call.
 
 lldb::addr_t
-AppleGetPendingItemsHandler::SetupGetPendingItemsFunction (Thread &thread, ValueList &get_pending_items_arglist)
+AppleGetPendingItemsHandler::SetupGetPendingItemsFunction(Thread &thread, ValueList &get_pending_items_arglist)
 {
-    ExecutionContext exe_ctx (thread.shared_from_this());
-    StreamString errors;
-    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_SYSTEM_RUNTIME));
+    ExecutionContext exe_ctx(thread.shared_from_this());
+    DiagnosticManager diagnostics;
+    Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SYSTEM_RUNTIME));
     lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
     FunctionCaller *get_pending_items_caller = nullptr;
-    
+
     // Scope for mutex locker:
     {
         Mutex::Locker locker(m_get_pending_items_function_mutex);
@@ -165,11 +166,14 @@ AppleGetPendingItemsHandler::SetupGetPendingItemsFunction (Thread &thread, Value
                         log->Printf ("Failed to get UtilityFunction for pending-items introspection: %s.", error.AsCString());
                     return args_addr;
                 }
-                
-                if (!m_get_pending_items_impl_code->Install(errors, exe_ctx))
+
+                if (!m_get_pending_items_impl_code->Install(diagnostics, exe_ctx))
                 {
                     if (log)
-                        log->Printf ("Failed to install pending-items introspection: %s.", errors.GetData());
+                    {
+                        log->Printf("Failed to install pending-items introspection.");
+                        diagnostics.Dump(log);
+                    }
                     m_get_pending_items_impl_code.reset();
                     return args_addr;
                 }
@@ -196,11 +200,10 @@ AppleGetPendingItemsHandler::SetupGetPendingItemsFunction (Thread &thread, Value
                 return args_addr;
             }
         }
-
     }
-    
-    errors.Clear();
-    
+
+    diagnostics.Clear();
+
     if (get_pending_items_caller == nullptr)
     {
         if (log)
@@ -212,13 +215,17 @@ AppleGetPendingItemsHandler::SetupGetPendingItemsFunction (Thread &thread, Value
     // if other threads were calling into here, but actually it isn't because we allocate a new args structure for
     // this call by passing args_addr = LLDB_INVALID_ADDRESS...
 
-    if (!get_pending_items_caller->WriteFunctionArguments (exe_ctx, args_addr, get_pending_items_arglist, errors))
+    if (!get_pending_items_caller->WriteFunctionArguments(exe_ctx, args_addr, get_pending_items_arglist, diagnostics))
     {
         if (log)
-            log->Printf ("Error writing pending-items function arguments: \"%s\".", errors.GetData());
+        {
+            log->Printf("Error writing pending-items function arguments.");
+            diagnostics.Dump(log);
+        }
+
         return args_addr;
     }
-        
+
     return args_addr;
 }
 
@@ -322,12 +329,12 @@ AppleGetPendingItemsHandler::GetPendingItems (Thread &thread, addr_t queue, addr
     page_to_free_size_value.GetScalar() = page_to_free_size;
     argument_values.PushValue (page_to_free_size_value);
 
-    addr_t args_addr = SetupGetPendingItemsFunction (thread, argument_values);
+    addr_t args_addr = SetupGetPendingItemsFunction(thread, argument_values);
 
-    StreamString errors;
+    DiagnosticManager diagnostics;
     ExecutionContext exe_ctx;
     FunctionCaller *get_pending_items_caller = m_get_pending_items_impl_code->GetFunctionCaller();
-    
+
     EvaluateExpressionOptions options;
     options.SetUnwindOnError (true);
     options.SetIgnoreBreakpoints (true);
@@ -342,10 +349,9 @@ AppleGetPendingItemsHandler::GetPendingItems (Thread &thread, addr_t queue, addr
         return return_value;
     }
 
-
     ExpressionResults func_call_ret;
     Value results;
-    func_call_ret =  get_pending_items_caller->ExecuteFunction (exe_ctx, &args_addr, options, errors, results);
+    func_call_ret = get_pending_items_caller->ExecuteFunction(exe_ctx, &args_addr, options, diagnostics, results);
     if (func_call_ret != eExpressionCompleted || !error.Success())
     {
         if (log)
diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetQueuesHandler.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetQueuesHandler.cpp
index 3370b3257a2..e005d500e0c 100644
--- a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetQueuesHandler.cpp
+++ b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetQueuesHandler.cpp
@@ -18,6 +18,7 @@
 #include "lldb/Core/Module.h"
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/Value.h"
+#include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/FunctionCaller.h"
 #include "lldb/Expression/UtilityFunction.h"
 #include "lldb/Symbol/ClangASTContext.h"
@@ -146,12 +147,12 @@ AppleGetQueuesHandler::Detach ()
 lldb::addr_t
 AppleGetQueuesHandler::SetupGetQueuesFunction (Thread &thread, ValueList &get_queues_arglist)
 {
-    ExecutionContext exe_ctx (thread.shared_from_this());
+    ExecutionContext exe_ctx(thread.shared_from_this());
     Address impl_code_address;
-    StreamString errors;
-    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_SYSTEM_RUNTIME));
+    DiagnosticManager diagnostics;
+    Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SYSTEM_RUNTIME));
     lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
-    
+
     FunctionCaller *get_queues_caller = nullptr;
 
     // Scope for mutex locker:
@@ -175,11 +176,14 @@ AppleGetQueuesHandler::SetupGetQueuesFunction (Thread &thread, ValueList &get_qu
                         log->Printf ("Failed to get UtilityFunction for queues introspection: %s.", error.AsCString());
                     return args_addr;
                 }
-                
-                if (!m_get_queues_impl_code_up->Install(errors, exe_ctx))
+
+                if (!m_get_queues_impl_code_up->Install(diagnostics, exe_ctx))
                 {
                     if (log)
-                        log->Printf ("Failed to install queues introspection: %s.", errors.GetData());
+                    {
+                        log->Printf("Failed to install queues introspection");
+                        diagnostics.Dump(log);
+                    }
                     m_get_queues_impl_code_up.reset();
                     return args_addr;
                 }
@@ -187,12 +191,14 @@ AppleGetQueuesHandler::SetupGetQueuesFunction (Thread &thread, ValueList &get_qu
             else
             {
                 if (log)
+                {
                     log->Printf("No queues introspection code found.");
-                errors.Printf ("No queues introspection code found.");
+                    diagnostics.Dump(log);
+                }
                 return LLDB_INVALID_ADDRESS;
             }
         }
-        
+
         // Next make the runner function for our implementation utility function.
         ClangASTContext *clang_ast_context = thread.GetProcess()->GetTarget().GetScratchClangASTContext();
         CompilerType get_queues_return_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
@@ -207,20 +213,23 @@ AppleGetQueuesHandler::SetupGetQueuesFunction (Thread &thread, ValueList &get_qu
             return args_addr;
         }
     }
-    
-    errors.Clear();
-    
+
+    diagnostics.Clear();
+
     // Now write down the argument values for this particular call.  This looks like it might be a race condition
     // if other threads were calling into here, but actually it isn't because we allocate a new args structure for
     // this call by passing args_addr = LLDB_INVALID_ADDRESS...
 
-    if (!get_queues_caller->WriteFunctionArguments (exe_ctx, args_addr, get_queues_arglist, errors))
+    if (!get_queues_caller->WriteFunctionArguments(exe_ctx, args_addr, get_queues_arglist, diagnostics))
     {
         if (log)
-            log->Printf ("Error writing get-queues function arguments: \"%s\".", errors.GetData());
+        {
+            log->Printf("Error writing get-queues function arguments.");
+            diagnostics.Dump(log);
+        }
         return args_addr;
     }
-        
+
     return args_addr;
 }
 
@@ -332,10 +341,10 @@ AppleGetQueuesHandler::GetCurrentQueues (Thread &thread, addr_t page_to_free, ui
         return return_value;
     }
 
-    StreamString errors;
+    DiagnosticManager diagnostics;
     ExecutionContext exe_ctx;
     EvaluateExpressionOptions options;
-    options.SetUnwindOnError (true);
+    options.SetUnwindOnError(true);
     options.SetIgnoreBreakpoints (true);
     options.SetStopOthers (true);
     options.SetTimeoutUsec(500000);
@@ -344,7 +353,7 @@ AppleGetQueuesHandler::GetCurrentQueues (Thread &thread, addr_t page_to_free, ui
 
     ExpressionResults func_call_ret;
     Value results;
-    func_call_ret =  get_queues_caller->ExecuteFunction (exe_ctx, &args_addr, options, errors, results);
+    func_call_ret = get_queues_caller->ExecuteFunction(exe_ctx, &args_addr, options, diagnostics, results);
     if (func_call_ret != eExpressionCompleted || !error.Success())
     {
         if (log)
diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp
index ba03f51152c..a528dafb97a 100644
--- a/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp
+++ b/lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetThreadItemInfoHandler.cpp
@@ -14,12 +14,12 @@
 // Other libraries and framework includes
 // Project includes
 
-#include "lldb/lldb-private.h"
 #include "lldb/Core/ConstString.h"
 #include "lldb/Core/Log.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/Value.h"
+#include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/Expression.h"
 #include "lldb/Expression/FunctionCaller.h"
 #include "lldb/Expression/UtilityFunction.h"
@@ -30,6 +30,7 @@
 #include "lldb/Target/StackFrame.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/Thread.h"
+#include "lldb/lldb-private.h"
 
 using namespace lldb;
 using namespace lldb_private;
@@ -141,10 +142,10 @@ AppleGetThreadItemInfoHandler::Detach ()
 lldb::addr_t
 AppleGetThreadItemInfoHandler::SetupGetThreadItemInfoFunction (Thread &thread, ValueList &get_thread_item_info_arglist)
 {
-    ExecutionContext exe_ctx (thread.shared_from_this());
+    ExecutionContext exe_ctx(thread.shared_from_this());
     Address impl_code_address;
-    StreamString errors;
-    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_SYSTEM_RUNTIME));
+    DiagnosticManager diagnostics;
+    Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SYSTEM_RUNTIME));
     lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
     FunctionCaller *get_thread_item_info_caller = nullptr;
 
@@ -171,11 +172,15 @@ AppleGetThreadItemInfoHandler::SetupGetThreadItemInfoFunction (Thread &thread, V
                     m_get_thread_item_info_impl_code.reset();
                     return args_addr;
                 }
-                
-                if (!m_get_thread_item_info_impl_code->Install(errors, exe_ctx))
+
+                if (!m_get_thread_item_info_impl_code->Install(diagnostics, exe_ctx))
                 {
                     if (log)
-                        log->Printf ("Failed to install get-thread-item-info introspection: %s.", errors.GetData());
+                    {
+                        log->Printf("Failed to install get-thread-item-info introspection.");
+                        diagnostics.Dump(log);
+                    }
+
                     m_get_thread_item_info_impl_code.reset();
                     return args_addr;
                 }
@@ -184,10 +189,9 @@ AppleGetThreadItemInfoHandler::SetupGetThreadItemInfoFunction (Thread &thread, V
             {
                 if (log)
                     log->Printf("No get-thread-item-info introspection code found.");
-                errors.Printf ("No get-thread-item-info introspection code found.");
                 return LLDB_INVALID_ADDRESS;
             }
-            
+
             // Also make the FunctionCaller for this UtilityFunction:
             
             ClangASTContext *clang_ast_context = thread.GetProcess()->GetTarget().GetScratchClangASTContext();
@@ -210,20 +214,24 @@ AppleGetThreadItemInfoHandler::SetupGetThreadItemInfoFunction (Thread &thread, V
             get_thread_item_info_caller = m_get_thread_item_info_impl_code->GetFunctionCaller();
         }
     }
-    
-    errors.Clear();
-    
+
+    diagnostics.Clear();
+
     // Now write down the argument values for this particular call.  This looks like it might be a race condition
     // if other threads were calling into here, but actually it isn't because we allocate a new args structure for
     // this call by passing args_addr = LLDB_INVALID_ADDRESS...
 
-    if (!get_thread_item_info_caller->WriteFunctionArguments (exe_ctx, args_addr, get_thread_item_info_arglist, errors))
+    if (!get_thread_item_info_caller->WriteFunctionArguments(exe_ctx, args_addr, get_thread_item_info_arglist,
+                                                             diagnostics))
     {
         if (log)
-            log->Printf ("Error writing get-thread-item-info function arguments: \"%s\".", errors.GetData());
+        {
+            log->Printf("Error writing get-thread-item-info function arguments");
+            diagnostics.Dump(log);
+        }
         return args_addr;
     }
-        
+
     return args_addr;
 }
 
@@ -324,13 +332,13 @@ AppleGetThreadItemInfoHandler::GetThreadItemInfo (Thread &thread, tid_t thread_i
     page_to_free_size_value.GetScalar() = page_to_free_size;
     argument_values.PushValue (page_to_free_size_value);
 
-    addr_t args_addr = SetupGetThreadItemInfoFunction (thread, argument_values);
+    addr_t args_addr = SetupGetThreadItemInfoFunction(thread, argument_values);
 
-    StreamString errors;
+    DiagnosticManager diagnostics;
     ExecutionContext exe_ctx;
     EvaluateExpressionOptions options;
     FunctionCaller *get_thread_item_info_caller = nullptr;
-    
+
     options.SetUnwindOnError (true);
     options.SetIgnoreBreakpoints (true);
     options.SetStopOthers (true);
@@ -354,7 +362,7 @@ AppleGetThreadItemInfoHandler::GetThreadItemInfo (Thread &thread, tid_t thread_i
 
     ExpressionResults func_call_ret;
     Value results;
-    func_call_ret =  get_thread_item_info_caller->ExecuteFunction (exe_ctx, &args_addr, options, errors, results);
+    func_call_ret = get_thread_item_info_caller->ExecuteFunction(exe_ctx, &args_addr, options, diagnostics, results);
     if (func_call_ret != eExpressionCompleted || !error.Success())
     {
         if (log)