[Sema] Make __attribute__((notnull)) inheritable through function parameters

[bettinson]

Summary

Fix PR 30828. __attribute__((notnull)) was not inheritable in the redefinition of a function. This is because attribute NonNull wasn't InheritableParamAttr, it was InheritableAttr. Clang will now emit warning after calling the redeclared function with a null argument.

This is my first patch into Clang, so I'll need someone to commit this for me.

Cheers

[bettinson]

ping

[ahatanak]

test/Sema/nonnull.c

171

Is this not pr30828?

[aaron.ballman]

Modulo the comment from @ahatanak, I think this looks good. Once you have addressed that comment, I can commit for you.

[bettinson]

Updated the test name. Sorry for the delay!

[aaron.ballman]

Committed in r297592, thank you!

include/clang/Basic/Attr.td

 }
 
 def NoSplitStack : InheritableAttr {
   let Spellings = [GCC<"no_split_stack">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [NoSplitStackDocs];
 }
 
-def NonNull : InheritableAttr {
+def NonNull : InheritableParamAttr {
   let Spellings = [GCC<"nonnull">];
   let Subjects = SubjectList<[ObjCMethod, HasFunctionProto, ParmVar], WarnDiag,
                              "ExpectedFunctionMethodOrParameter">;
   let Args = [VariadicUnsignedArgument<"Args">];
   let AdditionalMembers =
 [{bool isNonNull(unsigned idx) const {
     if (!args_size())
       return true;

test/Sema/nonnull.c

 
 void set_param_to_null(int**);
 int another_evil_nonnull_func(int* pointer, char ch, void * pv) __attribute__((nonnull(1, 3)));  // expected-note 2{{declared 'nonnull' here}}
 int another_evil_nonnull_func(int* pointer, char ch, void * pv) {
    if (pointer == NULL) { // expected-warning {{comparison of nonnull parameter 'pointer' equal to a null pointer is 'false' on first encounter}}
      return 0;
    } else {
      return *pointer;
-   } 
+   }
 
    set_param_to_null(&pointer);
    if (!pointer)
      return 0;
    else
      return *pointer;
 
    if (pv == NULL) {} // expected-warning {{comparison of nonnull parameter 'pv' equal to a null pointer is 'false' on first encounter}}
void returns_nonnull_warning_tests() {
   if (returns_nonnull_whee() != NULL) {} // expected-warning {{comparison of nonnull function call 'returns_nonnull_whee()' not equal to a null pointer is 'true' on first encounter}}
 
   if (returns_nonnull_whee()) {} // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
   if (!returns_nonnull_whee()) {} // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
 
   int and_again = !returns_nonnull_whee(); // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
   and_again = !returns_nonnull_whee(); // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
 }
+
+void pr30828(char *p __attribute__((nonnull)));
+void pr30828(char *p) {}
+
+void call_pr30828() {
+  pr30828(0); // expected-warning {{null passed to a callee that requires a non-null argument}}
+}