[clang][Diagnostic] Don't warn about binary literals when using C23.

[collinfunk]

The C23 standard brought binary literals which were previously GNU extensions. Silence warnings from -Wgnu-binary-literal when using C23. This warning is implied by -Wpedantic.

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[llvmbot]

@llvm/pr-subscribers-clang

Author: Collin Funk (collinfunk)

Changes

The C23 standard brought binary literals which were previously GNU extensions. Silence warnings from -Wgnu-binary-literal when using C23. This warning is implied by -Wpedantic.

---

Full diff: https://github.com/llvm/llvm-project/pull/80244.diff

1 Files Affected:

• (modified) clang/lib/Lex/LiteralSupport.cpp (+11-5)

diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 0a78638f68051..add4ca76678de 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1358,11 +1358,17 @@ void NumericLiteralParser::ParseNumberStartingWithZero(SourceLocation TokLoc) {
 
   // Handle simple binary numbers 0b01010
   if ((c1 == 'b' || c1 == 'B') && (s[1] == '0' || s[1] == '1')) {
-    // 0b101010 is a C++1y / GCC extension.
-    Diags.Report(TokLoc, LangOpts.CPlusPlus14
-                             ? diag::warn_cxx11_compat_binary_literal
-                         : LangOpts.CPlusPlus ? diag::ext_binary_literal_cxx14
-                                              : diag::ext_binary_literal);
+    // 0b101010 is a GCC extension subsequently standardized by C23 and C++14.
+    if (LangOpts.CPlusPlus) {
+      if (LangOpts.CPlusPlus14)
+        Diags.Report(TokLoc, diag::warn_cxx11_compat_binary_literal);
+      else
+        Diags.Report(TokLoc, diag::ext_binary_literal_cxx14);
+    } else {
+      // TODO: Need new DiagGroup for C23.
+      if (!LangOpts.C23)
+        Diags.Report(TokLoc, diag::ext_binary_literal);
+    }
     ++s;
     assert(s < ThisTokEnd && "didn't maximally munch?");
     radix = 2;

[shafik]

Thank you for this PR. This change should have some tests to verify the behavior is correct. I am a little surprised that this does not change any existing tests but maybe we don't have good test coverage.

[collinfunk]

Thank you for this PR. This change should have some tests to verify the behavior is correct. I am a little surprised that this does not change any existing tests but maybe we don't have good test coverage.

Hi, thanks for the review. Sorry for the lack of tests. I'm not super familiar with LLVM's code and didn't know how to add them. In any case, I believe that this issue was fixed in the following pull requests along with better Diagnostic groups:

#81658

Can you double check and make sure I am not mistaken? Thanks.

[cor3ntin]

#81658 replaces this PR