[PATCH] D155610: [Clang][Sema] Fix display of characters on static assertion failure

[Hubert Tong via Phabricator via cfe-commits]

hubert.reinterpretcast added inline comments.


================
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:16899
+          uint32_t CodePoint = static_cast<uint32_t>(V.getInt().getZExtValue());
+          PrintCharLiteralPrefix(BTy->getKind(), OS);
+          OS << '\'';
----------------
hubert.reinterpretcast wrote:
> cor3ntin wrote:
> > Looking at the diagnostics, I don't think it makes sense to print a prefix here. You could just leave that part out.
> Why is removing the prefix better? The types can matter (characters outside the basic character set are allowed to have negative `char` values). Also, moving forward, the value of a character need not be the same in the various encodings.
Some fun with signedness (imagine a more realistic example with `ISO-8859-1` ordinary character encoding with a signed `char` type):
```
$ clang -Xclang -fwchar-type=short -xc++ -<<<$'static_assert(L"\\uFF10"[0] == U\'\\uFF10\');'
<stdin>:1:15: error: static assertion failed due to requirement 'L"\xFF10"[0] == U'\uff10''
    1 | static_assert(L"\uFF10"[0] == U'\uFF10');
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~
<stdin>:1:28: note: expression evaluates to ''０' (0xFF10) == '０' (0xFF10)'
    1 | static_assert(L"\uFF10"[0] == U'\uFF10');
      |               ~~~~~~~~~~~~~^~~~~~~~~~~~
1 error generated.
Return:  0x01:1   Fri Aug 11 23:49:02 2023 EDT
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155610/new/

https://reviews.llvm.org/D155610