[clang] [C2y] Handle FP-suffixes on prefixed octals (#141230) (PR #141695)

[Corentin Jabot via cfe-commits]

================
@@ -1432,14 +1432,26 @@ void NumericLiteralParser::ParseNumberStartingWithZero(SourceLocation TokLoc) {
     Diags.Report(TokLoc, DiagId);
     ++s;
     DigitsBegin = s;
-    SawOctalPrefix = true;
+    radix = 8;
+    s = SkipOctalDigits(s);
+    if (s == ThisTokEnd) {
+      // Done
+    } else if ((isHexDigit(*s) && *s != 'e' && *s != 'E' && *s != '.') &&
+               !isValidUDSuffix(LangOpts, StringRef(s, ThisTokEnd - s))) {
+      Diags.Report(Lexer::AdvanceToTokenCharacter(TokLoc, s - ThisTokBegin, SM,
+                                                  LangOpts),
+                   diag::err_invalid_digit)
+          << StringRef(s, 1) << 1;
+      hadError = true;
+    }
+    // Other suffixes will be diagnosed by the caller.
+    return;
   }
 
   auto _ = llvm::make_scope_exit([&] {
     // If we still have an octal value but we did not see an octal prefix,
     // diagnose as being an obsolescent feature starting in C2y.
-    if (radix == 8 && LangOpts.C2y && !SawOctalPrefix && !hadError &&
-        !IsSingleZero)
+    if (radix == 8 && LangOpts.C2y && !hadError && !IsSingleZero)
----------------
cor3ntin wrote:

Do we have tests showing `00.` , `01.` `0E1` etc do not produce extension warnings?

https://github.com/llvm/llvm-project/pull/141695