Diagnose unsafe uses of nil and __nonnull pointers.

This generalizes the checking of null arguments to also work with
values of pointer-to-function, reference-to-function, and block
pointer type, using the nullability information within the underling
function prototype to extend non-null checking, and diagnoses returns
of 'nil' within a function with a __nonnull return type.

Note that we don't warn about nil returns from Objective-C methods,
because it's common for Objective-C methods to mimic the nil-swallowing
behavior of the receiver by checking ostensibly non-null parameters
and returning nil from otherwise non-null methods in that
case.

It also diagnoses (via a separate flag) conversions from nullable to
nonnull pointers. It's a separate flag because this warning can be noisy.

llvm-svn: 240153

1 files changed, 7 insertions, 0 deletions

diff --git a/clang/test/Sema/non-null-warning.c b/clang/test/Sema/non-null-warning.c
index 0cabc713baf..6cd98e298e2 100644
--- a/clang/test/Sema/non-null-warning.c
+++ b/clang/test/Sema/non-null-warning.c
@@ -33,3 +33,10 @@ int *foo3(int * __nonnull x) { // expected-warning {{nullability specifier '__no
   return 0;
 }
 
+int * ret_nonnull() {
+  return 0; // expected-warning {{null returned from function that requires a non-null return value}}
+}
+
+int main () {
+  foo(0); // expected-warning {{null passed to a callee that requires a non-null argument}}
+}