[clang] [Clang] strengthen checks for 'main' function to meet [basic.start.main] p2 requirements (PR #101853)

[Mital Ashok via cfe-commits]

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@@ -3292,11 +3292,9 @@ bool FunctionDecl::isImmediateFunction() const {
 }
 
 bool FunctionDecl::isMain() const {
-  const TranslationUnitDecl *tunit =
-    dyn_cast<TranslationUnitDecl>(getDeclContext()->getRedeclContext());
-  return tunit &&
-         !tunit->getASTContext().getLangOpts().Freestanding &&
-         isNamed(this, "main");
+  const DeclContext *DC = getDeclContext();
+  return isNamed(this, "main") && !getLangOpts().Freestanding &&
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MitalAshok wrote:

This is slightly changed from `tunit->getASTContext()->getLangOpts().FreeStanding` to `getLangOpts().Freestanding`. Is there any reason for this change? I don't know if these can have different values, but better safe than sorry

https://github.com/llvm/llvm-project/pull/101853