Tests for successful format string passthrough

Author: mysterymath

clang/test/CodeGen/attr-modular-format.c

@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm %s -o - | FileCheck %s
+
+int printf(const char *fmt, ...)  __attribute__((modular_format(__modular_printf, "__printf", "float")));
+int myprintf(const char *fmt, ...)  __attribute__((modular_format(__modular_printf, "__printf", "float"), format(printf, 1, 2)));
+
+// CHECK-LABEL: define dso_local void @test_inferred_format(
+// CHECK:    {{.*}} = call i32 (ptr, ...) @printf(ptr noundef @.str) #[[ATTR:[0-9]+]]
+void test_inferred_format(void) {
+  printf("hello");
+}
+
+// CHECK-LABEL: define dso_local void @test_explicit_format(
+// CHECK:    {{.*}} = call i32 (ptr, ...) @myprintf(ptr noundef @.str) #[[ATTR:[0-9]+]]
+void test_explicit_format(void) {
+  myprintf("hello");
+}
+
+// CHECK: attributes #[[ATTR]] = { "modular-format"="printf,1,2,__modular_printf,__printf,float" }