Diagnose variadic main() as an extension; addresses PR17905.

llvm-svn: 235605

3 files changed, 10 insertions, 0 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index d7b571888cc..b44aa37b9ec 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -485,6 +485,8 @@ def warn_static_main : Warning<"'main' should not be declared static">,
     InGroup<Main>;
 def err_static_main : Error<"'main' is not allowed to be declared static">;
 def err_inline_main : Error<"'main' is not allowed to be declared inline">;
+def ext_variadic_main : ExtWarn<
+  "'main' is not allowed to be declared variadic">, InGroup<Main>;
 def ext_noreturn_main : ExtWarn<
   "'main' is not allowed to be declared _Noreturn">, InGroup<Main>;
 def note_main_remove_noreturn : Note<"remove '_Noreturn'">;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 5bb39cbf147..6916710036c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8252,6 +8252,12 @@ void Sema::CheckMain(FunctionDecl* FD, const DeclSpec& DS) {
 
   bool HasExtraParameters = (nparams > 3);
 
+  if (FTP->isVariadic()) {
+    Diag(FD->getLocation(), diag::ext_variadic_main);
+    // FIXME: if we had information about the location of the ellipsis, we
+    // could add a FixIt hint to remove it as a parameter.
+  }
+
   // Darwin passes an undocumented fourth argument of type char**.  If
   // other platforms start sprouting these, the logic below will start
   // getting shifty.
diff --git a/clang/test/Sema/warn-main.c b/clang/test/Sema/warn-main.c
index 58a6dfde108..4620663037e 100644
--- a/clang/test/Sema/warn-main.c
+++ b/clang/test/Sema/warn-main.c
@@ -29,3 +29,5 @@ _Noreturn int main() {
   return 0;
 }
 
+// expected-warning@+1 {{'main' is not allowed to be declared variadic}}
+int main(int argc, char**argv, ...) { return 0; }