[Sema] Check if a builtin is FunctionPrototype().

Don't assume it's always is. This prevents a crash in Sema while
trying to merge return type for a builtin w/out function prototype.
 
PR:		23086
Differential Revision:	http://reviews.llvm.org/D9235
Reviewed by:	rsmith

llvm-svn: 235806

2 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 6916710036c..339280614ff 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1749,7 +1749,7 @@ NamedDecl *Sema::LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID,
                                            Loc, Loc, II, R, /*TInfo=*/nullptr,
                                            SC_Extern,
                                            false,
-                                           /*hasPrototype=*/true);
+                                           R->isFunctionProtoType());
   New->setImplicit();
 
   // Create Decl objects for each parameter, adding them to the
diff --git a/clang/test/Sema/crash-invalid-builtin.c b/clang/test/Sema/crash-invalid-builtin.c
new file mode 100644
index 00000000000..1c5221fa40d
--- /dev/null
+++ b/clang/test/Sema/crash-invalid-builtin.c
@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -triple=x86_64-apple-darwin -fsyntax-only -verify %s
+// PR23086
+
+__builtin_isinf(...); // expected-warning {{type specifier missing, defaults to 'int'}} expected-error {{ISO C requires a named parameter before '...'}} // expected-error {{conflicting types for '__builtin_isinf'}} // expected-note {{'__builtin_isinf' is a builtin with type 'int ()'}}