Implement the -Wstrict-prototypes warning

This commit fixes PR20796. It implements the C only -Wstrict-prototypes warning.
Clang now emits a warning for function declarations which have no parameters
specified and for K&R function definitions with more than 0 parameters that are
not preceded by a previous prototype declaration.

The patch was originally submitted by Paul Titei!

rdar://15060615

Differential Revision: https://reviews.llvm.org/D16533

llvm-svn: 288896

2 files changed, 82 insertions, 0 deletions

diff --git a/clang/test/Sema/warn-strict-prototypes.c b/clang/test/Sema/warn-strict-prototypes.c
new file mode 100644
index 00000000000..496579c1f60
--- /dev/null
+++ b/clang/test/Sema/warn-strict-prototypes.c
@@ -0,0 +1,62 @@
+// RUN: %clang_cc1 -fsyntax-only -Wstrict-prototypes -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wstrict-prototypes -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+// function declaration with unspecified params
+void foo1(); // expected-warning {{this function declaration is not a prototype}}
+             // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:11}:"void"
+// function declaration with 0 params
+void foo2(void);
+
+// function definition with 0 params(for both cases),
+// valid according to 6.7.5.3/14
+void foo1() {}
+void foo2(void) {}
+
+// function type typedef unspecified params
+typedef void foo3(); // expected-warning {{this function declaration is not a prototype}}
+                     // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:19-[[@LINE-1]]:19}:"void"
+
+// global fp unspecified params
+void (*foo4)(); // expected-warning {{this function declaration is not a prototype}}
+                // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:14-[[@LINE-1]]:14}:"void"
+
+// struct member fp unspecified params
+struct { void (*foo5)(); } s; // expected-warning {{this function declaration is not a prototype}}
+                              // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:23-[[@LINE-1]]:23}:"void"
+
+// param fp unspecified params
+void bar2(void (*foo6)()) { // expected-warning {{this function declaration is not a prototype}}
+                            // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:24-[[@LINE-1]]:24}:"void"
+  // local fp unspecified params
+  void (*foo7)() = 0; // expected-warning {{this function declaration is not a prototype}}
+                      // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:16-[[@LINE-1]]:16}:"void"
+  // array fp unspecified params
+  void (*foo8[2])() = {0}; // expected-warning {{this function declaration is not a prototype}}
+                           // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:19-[[@LINE-1]]:19}:"void"
+}
+
+// function type cast using using an anonymous function declaration
+void bar3(void) {
+  // casting function w/out prototype to unspecified params function type
+  (void)(void(*)()) foo1; // expected-warning {{this function declaration is not a prototype}}
+                          // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:18-[[@LINE-1]]:18}:"void"
+  // .. specified params
+  (void)(void(*)(void)) foo1;
+}
+
+// K&R function definition not preceded by full prototype
+int foo9(a, b) // expected-warning {{old-style function definition is not preceded by a prototype}}
+  int a, b;
+{
+  return a + b;
+}
+
+// Function declaration with no types
+void foo10(); // expected-warning {{this function declaration is not a prototype}}
+              // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:12-[[@LINE-1]]:12}:"void"
+// K&R function definition with incomplete param list declared
+void foo10(p, p2) void *p; {} // expected-warning {{old-style function definition is not preceded by a prototype}}
+
+// K&R function definition with previous prototype declared is not diagnosed.
+void foo11(int p, int p2);
+void foo11(p, p2) int p; int p2; {}
diff --git a/clang/test/Sema/warn-strict-prototypes.m b/clang/test/Sema/warn-strict-prototypes.m
new file mode 100644
index 00000000000..cbb01a1f7b2
--- /dev/null
+++ b/clang/test/Sema/warn-strict-prototypes.m
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -fsyntax-only -Wstrict-prototypes -verify -fblocks %s
+
+@interface Foo
+
+@property (nonatomic, copy) void (^noProtoBlock)(); // expected-warning {{this function declaration is not a prototype}}
+@property (nonatomic, copy) void (^block)(void); // no warning
+
+- doStuff:(void (^)()) completionHandler; // expected-warning {{this function declaration is not a prototype}}
+- doOtherStuff:(void (^)(void)) completionHandler; // no warning
+
+@end
+
+void foo() {
+  void (^block)() = // expected-warning {{this function declaration is not a prototype}}
+                    ^void(int arg) { // no warning
+  };
+  void (^block2)(void) = // no warning
+                         ^void() { // expected-warning {{this function declaration is not a prototype}}
+  };
+}