[PATCH] D127363: [Lex] Fix for char32_t literal truncation on 16 bit architectures

[Tom Honermann via Phabricator via cfe-commits]

tahonermann requested changes to this revision.
tahonermann added a comment.
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Comment at: clang/lib/Lex/LiteralSupport.cpp:1600
 
-  llvm::APInt LitVal(PP.getTargetInfo().getIntWidth(), 0);
+  llvm::APInt LitVal(PP.getTargetInfo().getChar32Width(), 0);
 
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I don't think this is quite right. For the code that follows this change to work as intended and issue the "Character constant too long for its type" diagnostic, the width needs to match that of `int`. This is required for multicharacter literals (they have type `int`) so that an appropriate diagnostic is issued for `'xxxxx'` for targets that have a 32-bit int (or for `'xxx'` for targets that have a 16-bit int)`.

Additionally, the type of a character constant in C is `int`.

I think what is needed is something like:
  unsigned BitWidth = getCharWidth(Kind, PP.getTargetInfo());
  if (IsMultiChar || !PP.getLangOpts().CPlusPlus)
    BitWidth = PP.getTargetInfo().getIntWidth();
  llvm::APInt LitVal(BitWidth, 0);


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D127363/new/

https://reviews.llvm.org/D127363