clang/test/Analysis/nullability.c

   1 // RUN: %clang_analyze_cc1 -fblocks -analyzer-checker=core,nullability,debug.ExprInspection -verify %s
   2
   3 void clang_analyzer_warnIfReached(void);
   4
   5 void it_takes_two(int a, int b);
   6 void function_pointer_arity_mismatch(void) {
   7   void(*fptr)() = it_takes_two;
   8   fptr(1); // no-crash expected-warning {{Function taking 2 arguments is called with fewer (1)}}
   9   // expected-warning@-1 {{passing arguments to a function without a prototype is deprecated in all versions of C and is not supported in C23}}
  10 }
  11
  12 void block_arity_mismatch(void) {
  13   void(^b)() = ^(int a, int b) { };
  14   b(1);  // no-crash expected-warning {{Block taking 2 arguments is called with fewer (1)}}
  15   // expected-warning@-1 {{passing arguments to a function without a prototype is deprecated in all versions of C and is not supported in C23}}
  16 }
  17
  18 int *nonnull_return_annotation_indirect(void) __attribute__((returns_nonnull));
  19 int *nonnull_return_annotation_indirect(void) {
  20   int *x = 0;
  21   return x; // expected-warning {{Null returned from a function that is expected to return a non-null value}}
  22 }
  23
  24 int *nonnull_return_annotation_direct(void) __attribute__((returns_nonnull));
  25 int *nonnull_return_annotation_direct(void) {
  26   return 0; // expected-warning {{Null returned from a function that is expected to return a non-null value}}
  27 } // expected-warning@-1 {{null returned from function that requires a non-null return value}}
  28
  29 int *nonnull_return_annotation_assumed(int* ptr) __attribute__((returns_nonnull));
  30 int *nonnull_return_annotation_assumed(int* ptr) {
  31   if (ptr) {
  32     return ptr;
  33   }
  34   return ptr; // expected-warning {{Null returned from a function that is expected to return a non-null value}}
  35 }
  36
  37 int *produce_nonnull_ptr(void) __attribute__((returns_nonnull));
  38
  39 __attribute__((returns_nonnull))
  40 int *cannot_return_null(void) {
  41   int *x = produce_nonnull_ptr();
  42   if (!x) {
  43     clang_analyzer_warnIfReached();
  44     // expected-warning@-1 {{REACHABLE}}
  45     // TODO: This warning is a false positive, according to the contract of
  46     // produce_nonnull_ptr, x cannot be null.
  47   }
  48   // Regardless of the potential state split above, x cannot be nullptr
  49   // according to the produce_nonnull_ptr annotation.
  50   return x;
  51   // False positive: expected-warning@-1 {{Null returned from a function that is expected to return a non-null value}}
  52 }
  53
  54 __attribute__((returns_nonnull)) int *passthrough(int *p) {
  55   return p; // no-warning: we have no evidence that `p` is null, i.e., violating the contract
  56 }
  57
  58 __attribute__((returns_nonnull)) int *passthrough2(int *p);
  59 int *passthrough2(int *p) {
  60   return p; // expected-warning{{Null returned from a function that is expected to return a non-null value}}
  61 }
  62
  63 void call_with_null(void) {
  64   passthrough2(0);
  65 }