[clang] [clang] Do not compute typo-correction suggestions for disabled diagnostics (PR #209694)

[Corentin Jabot via cfe-commits]

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@@ -514,6 +515,20 @@ void Preprocessor::SuggestTypoedDirective(const Token &Tok,
   // directives.
   if (getLangOpts().AsmPreprocessor) return;
 
+  // A known non-conditional directive (e.g. #include or #define inside a
+  // skipped conditional block) is not a typo of a conditional don't scan
+  // it. #elifdef/#elifndef stay eligible so that pre-C23/C++23 code still
+  // gets the "did you mean #elif" suggestion.
+  if (tok::PPKeywordKind K = getIdentifierInfo(Directive)->getPPKeywordID();
+      K != tok::pp_not_keyword && K != tok::pp_elifdef && K != tok::pp_elifndef)
+    return;
+
+  // The scan only feeds this diagnostic; skip it when the diagnostic is
+  // disabled at this location (e.g. -w).
+  if (getDiagnostics().isIgnored(diag::warn_pp_invalid_directive,
+                                 Tok.getLocation()))
+    return;
+
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cor3ntin wrote:

we could do that earlier (after checking for asm)

https://github.com/llvm/llvm-project/pull/209694