850269a47e
Currently, we emit warnings in some cases where nonnull function
parameters are compared against null. This patch extends this support
to warn when comparing the result of `returns_nonnull` functions
against null.
More specifically, we will now warn cases like:
int *foo() __attribute__((returns_nonnull));
int main() {
if (foo() == NULL) {} // warning: will always evaluate to false
}
Differential Revision: http://reviews.llvm.org/D15324
llvm-svn: 255058
170 lines
6.5 KiB
C
170 lines
6.5 KiB
C
// RUN: %clang_cc1 -fsyntax-only -verify %s
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// rdar://9584012
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typedef struct {
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char *str;
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} Class;
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typedef union {
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Class *object;
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} Instance __attribute__((transparent_union));
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__attribute__((nonnull(1))) void Class_init(Instance this, char *str) {
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this.object->str = str;
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}
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int main(void) {
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Class *obj;
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Class_init(0, "Hello World"); // expected-warning {{null passed to a callee that requires a non-null argument}}
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Class_init(obj, "Hello World");
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}
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void foo(const char *str) __attribute__((nonnull("foo"))); // expected-error{{'nonnull' attribute requires parameter 1 to be an integer constant}}
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void bar(int i) __attribute__((nonnull(1))); // expected-warning {{'nonnull' attribute only applies to pointer arguments}} expected-warning {{'nonnull' attribute applied to function with no pointer arguments}}
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void baz(__attribute__((nonnull)) const char *str);
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void baz2(__attribute__((nonnull(1))) const char *str); // expected-warning {{'nonnull' attribute when used on parameters takes no arguments}}
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void baz3(__attribute__((nonnull)) int x); // expected-warning {{'nonnull' attribute only applies to pointer arguments}}
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void test_baz() {
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baz(0); // expected-warning {{null passed to a callee that requires a non-null argument}}
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baz2(0); // no-warning
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baz3(0); // no-warning
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}
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void test_void_returns_nonnull(void) __attribute__((returns_nonnull)); // expected-warning {{'returns_nonnull' attribute only applies to return values that are pointers}}
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int test_int_returns_nonnull(void) __attribute__((returns_nonnull)); // expected-warning {{'returns_nonnull' attribute only applies to return values that are pointers}}
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void *test_ptr_returns_nonnull(void) __attribute__((returns_nonnull)); // no-warning
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int i __attribute__((nonnull)); // expected-warning {{'nonnull' attribute only applies to functions, methods, and parameters}}
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int j __attribute__((returns_nonnull)); // expected-warning {{'returns_nonnull' attribute only applies to functions and methods}}
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void *test_no_fn_proto() __attribute__((returns_nonnull)); // no-warning
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void *test_with_fn_proto(void) __attribute__((returns_nonnull)); // no-warning
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__attribute__((returns_nonnull))
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void *test_bad_returns_null(void) {
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return 0; // expected-warning {{null returned from function that requires a non-null return value}}
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}
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void PR18795(int (*g)(const char *h, ...) __attribute__((nonnull(1))) __attribute__((nonnull))) {
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g(0); // expected-warning{{null passed to a callee that requires a non-null argument}}
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}
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void PR18795_helper() {
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PR18795(0); // expected-warning{{null passed to a callee that requires a non-null argument}}
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}
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void vararg1(int n, ...) __attribute__((nonnull(2)));
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void vararg1_test() {
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vararg1(0);
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vararg1(1, (void*)0); // expected-warning{{null passed}}
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vararg1(2, (void*)0, (void*)0); // expected-warning{{null passed}}
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vararg1(2, (void*)&vararg1, (void*)0);
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}
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void vararg2(int n, ...) __attribute__((nonnull, nonnull, nonnull));
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void vararg2_test() {
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vararg2(0);
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vararg2(1, (void*)0); // expected-warning{{null passed}}
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vararg2(2, (void*)0, (void*)0); // expected-warning 2{{null passed}}
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}
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void vararg3(int n, ...) __attribute__((nonnull, nonnull(2), nonnull(3)));
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void vararg3_test() {
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vararg3(0);
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vararg3(1, (void*)0); // expected-warning{{null passed}}
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vararg3(2, (void*)0, (void*)0); // expected-warning 2{{null passed}}
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}
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void redecl(void *, void *);
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void redecl(void *, void *) __attribute__((nonnull(1)));
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void redecl(void *, void *) __attribute__((nonnull(2)));
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void redecl(void *, void *);
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void redecl_test(void *p) {
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redecl(p, 0); // expected-warning{{null passed}}
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redecl(0, p); // expected-warning{{null passed}}
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}
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// rdar://18712242
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#define NULL (void*)0
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__attribute__((__nonnull__))
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int evil_nonnull_func(int* pointer, void * pv)
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{
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if (pointer == NULL) { // expected-warning {{comparison of nonnull parameter 'pointer' equal to a null pointer is 'false' on first encounter}}
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return 0;
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} else {
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return *pointer;
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}
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pointer = pv;
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if (!pointer)
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return 0;
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else
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return *pointer;
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if (pv == NULL) {} // expected-warning {{comparison of nonnull parameter 'pv' equal to a null pointer is 'false' on first encounter}}
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}
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void set_param_to_null(int**);
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int another_evil_nonnull_func(int* pointer, char ch, void * pv) __attribute__((nonnull(1, 3)));
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int another_evil_nonnull_func(int* pointer, char ch, void * pv) {
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if (pointer == NULL) { // expected-warning {{comparison of nonnull parameter 'pointer' equal to a null pointer is 'false' on first encounter}}
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return 0;
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} else {
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return *pointer;
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}
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set_param_to_null(&pointer);
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if (!pointer)
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return 0;
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else
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return *pointer;
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if (pv == NULL) {} // expected-warning {{comparison of nonnull parameter 'pv' equal to a null pointer is 'false' on first encounter}}
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}
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extern void *returns_null(void**);
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extern void FOO();
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extern void FEE();
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extern void *pv;
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__attribute__((__nonnull__))
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void yet_another_evil_nonnull_func(int* pointer)
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{
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while (pv) {
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// This comparison will not be optimized away.
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if (pointer) { // expected-warning {{nonnull parameter 'pointer' will evaluate to 'true' on first encounter}}
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FOO();
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} else {
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FEE();
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}
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pointer = returns_null(&pv);
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}
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}
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void pr21668_1(__attribute__((nonnull)) const char *p, const char *s) {
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if (p) // expected-warning {{nonnull parameter 'p' will evaluate to 'true' on first encounter}}
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;
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if (s) // No warning
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;
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}
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void pr21668_2(__attribute__((nonnull)) const char *p) {
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p = 0;
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if (p) // No warning
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;
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}
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__attribute__((returns_nonnull)) void *returns_nonnull_whee();
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void returns_nonnull_warning_tests() {
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if (returns_nonnull_whee() == NULL) {} // expected-warning {{comparison of nonnull function call 'returns_nonnull_whee()' equal to a null pointer is 'false' on first encounter}}
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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}}
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if (returns_nonnull_whee()) {} // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
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if (!returns_nonnull_whee()) {} // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
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int and_again = !returns_nonnull_whee(); // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
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and_again = !returns_nonnull_whee(); // expected-warning {{nonnull function call 'returns_nonnull_whee()' will evaluate to 'true' on first encounter}}
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}
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