clang: Exclude efi_main from -Wmissing-prototypes

[DaanDeMeyer]

Summary

When compiling UEFI applications, the main function is named
efi_main() instead of main(). Let's exclude efi_main() from
-Wmissing-prototypes as well to avoid warnings when working
on UEFI applications.

[DaanDeMeyer]

CI failures seem unrelated?

[dblaikie]

Please include test coverage

[DaanDeMeyer]

Added a test

[dblaikie]

Looks good to me - maybe the test could be rolled into whatever file is already testing -Wmissing-prototype and the existing special case for "main"?

Do you need me to commit this, or can you commit it yourself?

[DaanDeMeyer]

Moved the test into the no-warn-missing-prototype test as requested.

[DaanDeMeyer]

I should be able to commit it myself. Thanks for the review!

[dblaikie]

Reaffirming approval with the test change - looks great!

clang/lib/Sema/SemaDecl.cpp

ShouldWarnAboutMissingPrototype(const FunctionDecl *FD,
 
   // Don't warn about C++ member functions.
   if (isa<CXXMethodDecl>(FD))
     return false;
 
   // Don't warn about 'main'.
   if (isa<TranslationUnitDecl>(FD->getDeclContext()->getRedeclContext()))
     if (IdentifierInfo *II = FD->getIdentifier())
-      if (II->isStr("main"))
+      if (II->isStr("main") || II->isStr("efi_main"))
         return false;
 
   // Don't warn about inline functions.
   if (FD->isInlined())
     return false;
 
   // Don't warn about function templates.
   if (FD->getDescribedFunctionTemplate())

clang/test/Sema/no-warn-missing-prototype.c

 // RUN: %clang_cc1 -fsyntax-only -Wmissing-prototypes -x c -ffreestanding -verify %s
 // RUN: %clang_cc1 -fsyntax-only -Wmissing-prototypes -x c++ -ffreestanding -verify %s
 // expected-no-diagnostics
 int main() {
   return 0;
 }
+
+int efi_main() {
+  return 0;
+}