[clang-tidy] Re-commit: Add new 'readability-uppercase-literal-suffix' check (CERT DCL16-C, MISRA C:2012, 7.3, MISRA C++:2008, 2-13-4)

Summary:
Detects when the integral literal or floating point (decimal or hexadecimal)
literal has non-uppercase suffix, and suggests to make the suffix uppercase,
with fix-it.

All valid combinations of suffixes are supported.

```
  auto x = 1;  // OK, no suffix.

  auto x = 1u; // warning: integer literal suffix 'u' is not upper-case

  auto x = 1U; // OK, suffix is uppercase.

  ...
```

This is a re-commit, the original was reverted by me in
rL345305 due to discovered bugs. (implicit code, template instantiation)
Tests were added, and the bugs were fixed.
I'm unable to find any further bugs, hopefully there aren't any..

References:
* [[ https://wiki.sei.cmu.edu/confluence/pages/viewpage.action?pageId=87152241 | CERT DCL16-C ]]
* MISRA C:2012, 7.3 - The lowercase character "l" shall not be used in a literal suffix
* MISRA C++:2008, 2-13-4 - Literal suffixes shall be upper case

Reviewers: JonasToth, aaron.ballman, alexfh, hokein, xazax.hun

Reviewed By: aaron.ballman

Subscribers: Eugene.Zelenko, mgorny, rnkovacs, cfe-commits

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D52670

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@345381 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 38 insertions, 0 deletions

diff --git a/clang-tidy/utils/ASTUtils.cpp b/clang-tidy/utils/ASTUtils.cpp
index 5c6b9843..3c0427fd 100644
--- a/clang-tidy/utils/ASTUtils.cpp
+++ b/clang-tidy/utils/ASTUtils.cpp
@@ -67,6 +67,32 @@ bool exprHasBitFlagWithSpelling(const Expr *Flags, const SourceManager &SM,
   return true;
 }
 
+bool rangeIsEntirelyWithinMacroArgument(SourceRange Range,
+                                        const SourceManager *SM) {
+  // Check if the range is entirely contained within a macro argument.
+  SourceLocation MacroArgExpansionStartForRangeBegin;
+  SourceLocation MacroArgExpansionStartForRangeEnd;
+  bool RangeIsEntirelyWithinMacroArgument =
+      SM &&
+      SM->isMacroArgExpansion(Range.getBegin(),
+                              &MacroArgExpansionStartForRangeBegin) &&
+      SM->isMacroArgExpansion(Range.getEnd(),
+                              &MacroArgExpansionStartForRangeEnd) &&
+      MacroArgExpansionStartForRangeBegin == MacroArgExpansionStartForRangeEnd;
+
+  return RangeIsEntirelyWithinMacroArgument;
+}
+
+bool rangeContainsMacroExpansion(SourceRange Range, const SourceManager *SM) {
+  return rangeIsEntirelyWithinMacroArgument(Range, SM) ||
+         Range.getBegin().isMacroID() || Range.getEnd().isMacroID();
+}
+
+bool rangeCanBeFixed(SourceRange Range, const SourceManager *SM) {
+  return utils::rangeIsEntirelyWithinMacroArgument(Range, SM) ||
+         !utils::rangeContainsMacroExpansion(Range, SM);
+}
+
 } // namespace utils
 } // namespace tidy
 } // namespace clang
diff --git a/clang-tidy/utils/ASTUtils.h b/clang-tidy/utils/ASTUtils.h
index ccff000a..4196eeb9 100644
--- a/clang-tidy/utils/ASTUtils.h
+++ b/clang-tidy/utils/ASTUtils.h
@@ -27,6 +27,18 @@ bool IsBinaryOrTernary(const Expr *E);
 bool exprHasBitFlagWithSpelling(const Expr *Flags, const SourceManager &SM,
                                 const LangOptions &LangOpts,
                                 StringRef FlagName);
+
+// Check if the range is entirely contained within a macro argument.
+bool rangeIsEntirelyWithinMacroArgument(SourceRange Range,
+                                        const SourceManager *SM);
+
+// Check if the range contains any locations from a macro expansion.
+bool rangeContainsMacroExpansion(SourceRange Range, const SourceManager *SM);
+
+// Can a fix-it be issued for this whole Range?
+// FIXME: false-negative if the entire range is fully expanded from a macro.
+bool rangeCanBeFixed(SourceRange Range, const SourceManager *SM);
+
 } // namespace utils
 } // namespace tidy
 } // namespace clang