r212171 - Don't accept qualified 'int' main return types in C++ or standard C mode

[Alp Toker]

Author: alp
Date: Wed Jul  2 02:07:20 2014
New Revision: 212171

URL: http://llvm.org/viewvc/llvm-project?rev=212171&view=rev
Log:
Don't accept qualified 'int' main return types in C++ or standard C mode

C++ [basic.start.main]p1: "It shall have a return type of type int"

ISO C is also clear about this, so only accept 'int' with qualifiers in GNUMode
C.

Modified:
    cfe/trunk/lib/Sema/SemaDecl.cpp
    cfe/trunk/test/CXX/basic/basic.start/basic.start.main/p2.cpp
    cfe/trunk/test/Sema/c89.c

Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=212171&r1=212170&r2=212171&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDecl.cpp Wed Jul  2 02:07:20 2014
@@ -7878,32 +7878,37 @@ void Sema::CheckMain(FunctionDecl* FD, c
   assert(T->isFunctionType() && "function decl is not of function type");
   const FunctionType* FT = T->castAs<FunctionType>();
 
-  // All the standards say that main() should should return 'int'.
-  if (Context.hasSameUnqualifiedType(FT->getReturnType(), Context.IntTy)) {
+  if (getLangOpts().GNUMode && !getLangOpts().CPlusPlus) {
+    // In C with GNU extensions we allow main() to have non-integer return
+    // type, but we should warn about the extension, and we disable the
+    // implicit-return-zero rule.
+
+    // GCC in C mode accepts qualified 'int'.
+    if (Context.hasSameUnqualifiedType(FT->getReturnType(), Context.IntTy))
+      FD->setHasImplicitReturnZero(true);
+    else {
+      Diag(FD->getTypeSpecStartLoc(), diag::ext_main_returns_nonint);
+      SourceRange RTRange = FD->getReturnTypeSourceRange();
+      if (RTRange.isValid())
+        Diag(RTRange.getBegin(), diag::note_main_change_return_type)
+            << FixItHint::CreateReplacement(RTRange, "int");
+    }
+  } else {
     // In C and C++, main magically returns 0 if you fall off the end;
     // set the flag which tells us that.
     // This is C++ [basic.start.main]p5 and C99 5.1.2.2.3.
-    FD->setHasImplicitReturnZero(true);
-
-  // In C with GNU extensions we allow main() to have non-integer return
-  // type, but we should warn about the extension, and we disable the
-  // implicit-return-zero rule.
-  } else if (getLangOpts().GNUMode && !getLangOpts().CPlusPlus) {
-    Diag(FD->getTypeSpecStartLoc(), diag::ext_main_returns_nonint);
-
-    SourceRange RTRange = FD->getReturnTypeSourceRange();
-    if (RTRange.isValid())
-      Diag(RTRange.getBegin(), diag::note_main_change_return_type)
-          << FixItHint::CreateReplacement(RTRange, "int");
-
-  // Otherwise, this is just a flat-out error.
-  } else {
-    SourceRange RTRange = FD->getReturnTypeSourceRange();
-    Diag(FD->getTypeSpecStartLoc(), diag::err_main_returns_nonint)
-        << (RTRange.isValid() ? FixItHint::CreateReplacement(RTRange, "int")
-                              : FixItHint());
 
-    FD->setInvalidDecl(true);
+    // All the standards say that main() should return 'int'.
+    if (Context.hasSameType(FT->getReturnType(), Context.IntTy))
+      FD->setHasImplicitReturnZero(true);
+    else {
+      // Otherwise, this is just a flat-out error.
+      SourceRange RTRange = FD->getReturnTypeSourceRange();
+      Diag(FD->getTypeSpecStartLoc(), diag::err_main_returns_nonint)
+          << (RTRange.isValid() ? FixItHint::CreateReplacement(RTRange, "int")
+                                : FixItHint());
+      FD->setInvalidDecl(true);
+    }
   }
 
   // Treat protoless main() as nullary.

Modified: cfe/trunk/test/CXX/basic/basic.start/basic.start.main/p2.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/basic/basic.start/basic.start.main/p2.cpp?rev=212171&r1=212170&r2=212171&view=diff
==============================================================================
--- cfe/trunk/test/CXX/basic/basic.start/basic.start.main/p2.cpp (original)
+++ cfe/trunk/test/CXX/basic/basic.start/basic.start.main/p2.cpp Wed Jul  2 02:07:20 2014
@@ -62,6 +62,8 @@ main( // expected-error {{first paramete
 ) {
 }
 
+const int main(); // expected-error {{'main' must return 'int'}}
+
 #elif TEST7
 
 // expected-no-diagnostics

Modified: cfe/trunk/test/Sema/c89.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/c89.c?rev=212171&r1=212170&r2=212171&view=diff
==============================================================================
--- cfe/trunk/test/Sema/c89.c (original)
+++ cfe/trunk/test/Sema/c89.c Wed Jul  2 02:07:20 2014
@@ -111,6 +111,8 @@ const array_of_pointer_to_CI mine3;
 
 void main() {} /* expected-error {{'main' must return 'int'}} */
 
+const int main() {} /* expected-error {{'main' must return 'int'}} */
+
 long long ll1 = /* expected-warning {{'long long' is an extension when C99 mode is not enabled}} */
          -42LL; /* expected-warning {{'long long' is an extension when C99 mode is not enabled}} */
 unsigned long long ull1 = /* expected-warning {{'long long' is an extension when C99 mode is not enabled}} */