[clang] Add more tests for _Countof (PR #133333)
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Mon May 5 14:34:21 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Alejandro Colomar (alejandro-colomar)
<details>
<summary>Changes</summary>
Link: <https://github.com/llvm/llvm-project/issues/102836>
Link: <https://github.com/llvm/llvm-project/pull/133125>
Cc: @<!-- -->AaronBallman
I haven't yet tried to run these tests. I've pasted and adapted them from the ones I wrote for my own implementation. (I have a few more, which I'll adapt once I know I adapted these correctly.)
---
Revisions:
<details>
<summary>v2</summary>
- Fix some expected diagnostics
- Use `global_num` instead of `errno`.
```
$ git range-diff main gh/countof_tests countof_tests
1: fe746be5715d ! 1: a651447d3fac Add more tests for _Countof
@@ Commit message
Link: <https://github.com/llvm/llvm-project/issues/102836>
Link: <https://github.com/llvm/llvm-project/pull/133125>
+ Cc: Aaron Ballman <aaron@<!-- -->aaronballman.com>
Signed-off-by: Alejandro Colomar <alx@<!-- -->kernel.org>
## clang/test/C/C2y/n3369.c ##
@@ clang/test/C/C2y/n3369.c: void test_with_function_param(int array[12], int (*arr
(void)_Countof(static_array); // expected-error {{'_Countof' requires an argument of array type; 'int *' invalid}}
}
-+void test_func_fix_fix(int i, char (*a)[3][5], int (*x)[_Countof(*a)]);
-+void test_func_fix_var(int i, char (*a)[3][i], int (*x)[_Countof(*a)]);
-+void test_func_fix_uns(int i, char (*a)[3][*], int (*x)[_Countof(*a)]);
++void test_func_fix_fix(int i, char (*a)[3][5], int (*x)[_Countof(*a)]); // expected-note {{passing argument to parameter}}
++void test_func_fix_var(int i, char (*a)[3][i], int (*x)[_Countof(*a)]); // expected-note {{passing argument to parameter}}
++void test_func_fix_uns(int i, char (*a)[3][*], int (*x)[_Countof(*a)]); // expected-note {{passing argument to parameter}}
+
+void test_funcs() {
+ int i3[3];
+ int i5[5];
+ char c35[3][5];
+ test_func_fix_fix(5, &c35, &i3);
-+ test_func_fix_fix(5, &c35, &i5); // expected-error {{incompatible-pointer-types}}
++ test_func_fix_fix(5, &c35, &i5); // expected-error {{incompatible pointer types passing}}
+ test_func_fix_var(5, &c35, &i3);
-+ test_func_fix_var(5, &c35, &i5); // expected-error {{incompatible-pointer-types}}
++ test_func_fix_var(5, &c35, &i5); // expected-error {{incompatible pointer types passing}}
+ test_func_fix_uns(5, &c35, &i3);
-+ test_func_fix_uns(5, &c35, &i5); // expected-error {{incompatible-pointer-types}}
++ test_func_fix_uns(5, &c35, &i5); // expected-error {{incompatible pointer types passing}}
+}
+
void test_multidimensional_arrays() {
@@ clang/test/C/C2y/n3369.c: void test_unspecified_array_length() {
}
+void test_completed_array() {
-+ int a[] = {1, 2, errno};
++ int a[] = {1, 2, global_num};
+ static_assert(_Countof(a) == 3);
+}
+
```
</details>
<details>
<summary>v2b</summary>
- Fix expected diagnostic messages
```
$ git range-diff main gh/countof_tests countof_tests
1: a651447d3fac ! 1: 6c5c502ca376 Add more tests for _Countof
@@ clang/test/C/C2y/n3369.c: void test_with_function_param(int array[12], int (*arr
+ int i5[5];
+ char c35[3][5];
+ test_func_fix_fix(5, &c35, &i3);
-+ test_func_fix_fix(5, &c35, &i5); // expected-error {{incompatible pointer types passing}}
++ test_func_fix_fix(5, &c35, &i5); // expected-error {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+ test_func_fix_var(5, &c35, &i3);
-+ test_func_fix_var(5, &c35, &i5); // expected-error {{incompatible pointer types passing}}
++ test_func_fix_var(5, &c35, &i5); // expected-error {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+ test_func_fix_uns(5, &c35, &i3);
-+ test_func_fix_uns(5, &c35, &i5); // expected-error {{incompatible pointer types passing}}
++ test_func_fix_uns(5, &c35, &i5); // expected-error {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+}
+
void test_multidimensional_arrays() {
```
</details>
<details>
<summary>v2c</summary>
- Fix expected diagnostic type
```
$ git range-diff main gh/countof_tests countof_tests
1: 6c5c502ca376 ! 1: b8f95e71efec Add more tests for _Countof
@@ clang/test/C/C2y/n3369.c: void test_with_function_param(int array[12], int (*arr
+ int i5[5];
+ char c35[3][5];
+ test_func_fix_fix(5, &c35, &i3);
-+ test_func_fix_fix(5, &c35, &i5); // expected-error {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
++ test_func_fix_fix(5, &c35, &i5); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+ test_func_fix_var(5, &c35, &i3);
-+ test_func_fix_var(5, &c35, &i5); // expected-error {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
++ test_func_fix_var(5, &c35, &i5); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+ test_func_fix_uns(5, &c35, &i3);
-+ test_func_fix_uns(5, &c35, &i5); // expected-error {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
++ test_func_fix_uns(5, &c35, &i5); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+}
+
void test_multidimensional_arrays() {
```
</details>
<details>
<summary>v2d</summary>
- Fix expected diagnostics.
```
$ git range-diff main gh/countof_tests countof_tests
1: b8f95e71efec ! 1: eb63ad49de45 Add more tests for _Countof
@@ clang/test/C/C2y/n3369.c: void test_typedefs() {
int array[0]; // expected-warning {{zero size arrays are an extension}}
static_assert(_Countof(array) == 0);
static_assert(_Countof(int[0]) == 0); // expected-warning {{zero size arrays are an extension}}
-+ int multi_array[0][n]; // expected-warning {{zero size arrays are an extension}}
++ int multi_array[0][n]; // FIXME: Should trigger -Wzero-length-array
+ static_assert(_Countof(multi_array) == 0);
+ int another_one[0][3]; // expected-warning {{zero size arrays are an extension}}
+ static_assert(_Countof(another_one) == 0);
@@ clang/test/C/C2y/n3369.c: void test_compound_literals() {
}
+
+static int test_f1();
-+static int test_f2(); // expected-warning {{never defined}}
++static int test_f2(); // expected-warning {{function 'f' has internal linkage but is not defined}}
+
+void test_symbols() {
+ int a[global_num][global_num];
```
</details>
<details>
<summary>v2e</summary>
- Add comment about symbols.
- tfix
```
$ git range-diff main gh/countof_tests countof_tests
1: eb63ad49de45 ! 1: 3660f83ad4be Add more tests for _Countof
@@ clang/test/C/C2y/n3369.c: void test_compound_literals() {
static_assert(_Countof((int[]){1, 2, 3, 4}) == 4);
}
+
++/* We don't get a diagnostic for test_f1(), because it ends up unused
++ * as _Countof() results in an integer constant expression, which is not
++ * evaluated. However, test_f2() ends up being evaluated, since 'a' is
++ * a VLA.
++ */
+static int test_f1();
-+static int test_f2(); // expected-warning {{function 'f' has internal linkage but is not defined}}
++static int test_f2(); // expected-warning {{function 'test_f2' has internal linkage but is not defined}}
+
+void test_symbols() {
+ int a[global_num][global_num];
```
</details>
<details>
<summary>v3</summary>
- Change `expected-warning` into a FIXME note (pre-existing false negative).
- Add _Generic() code suggested by @<!-- -->frederick-vs-ja .
```
$ git range-diff main..@{u} main@{u}..HEAD
1: 3660f83ad4be ! 1: d393955db896 Add more tests for _Countof
@@ clang/test/C/C2y/n3369.c: void test_with_function_param(int array[12], int (*arr
(void)_Countof(static_array); // expected-error {{'_Countof' requires an argument of array type; 'int *' invalid}}
}
-+void test_func_fix_fix(int i, char (*a)[3][5], int (*x)[_Countof(*a)]); // expected-note {{passing argument to parameter}}
-+void test_func_fix_var(int i, char (*a)[3][i], int (*x)[_Countof(*a)]); // expected-note {{passing argument to parameter}}
-+void test_func_fix_uns(int i, char (*a)[3][*], int (*x)[_Countof(*a)]); // expected-note {{passing argument to parameter}}
++void test_func_fix_fix(int i, char (*a)[3][5], int (*x)[_Countof(*a)], char (*)[_Generic(x, int (*)[3]: 1)]); // expected-note {{passing argument to parameter}}
++void test_func_fix_var(int i, char (*a)[3][i], int (*x)[_Countof(*a)], char (*)[_Generic(x, int (*)[3]: 1)]); // expected-note {{passing argument to parameter}}
++void test_func_fix_uns(int i, char (*a)[3][*], int (*x)[_Countof(*a)], char (*)[_Generic(x, int (*)[3]: 1)]); // expected-note {{passing argument to parameter}}
+
+void test_funcs() {
+ int i3[3];
@@ clang/test/C/C2y/n3369.c: void test_compound_literals() {
+ * a VLA.
+ */
+static int test_f1();
-+static int test_f2(); // expected-warning {{function 'test_f2' has internal linkage but is not defined}}
++static int test_f2(); // FIXME: Should trigger function 'test_f2' has internal linkage but is not defined
+
+void test_symbols() {
+ int a[global_num][global_num];
```
</details>
<details>
<summary>v3b</summary>
- Rebase
```
$ git range-diff main..@{u} main@{u}..HEAD
1: d393955db896 = 1: 923856a504d8 Add more tests for _Countof
```
</details>
<details>
<summary>v3c</summary>
- Add missing parameter.
```
$ git range-diff main..@{u} main@{u}..HEAD
1: 923856a504d8 ! 1: f4f1f5661b0b Add more tests for _Countof
@@ Commit message
## clang/test/C/C2y/n3369.c ##
@@
+ #error "Expected to have _Countof support"
#endif
++#define NULL ((void *) 0)
++
int global_array[12];
+int global_multi_array[12][34];
+int global_num;
@@ clang/test/C/C2y/n3369.c: void test_with_function_param(int array[12], int (*arr
+ int i3[3];
+ int i5[5];
+ char c35[3][5];
-+ test_func_fix_fix(5, &c35, &i3);
-+ test_func_fix_fix(5, &c35, &i5); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
-+ test_func_fix_var(5, &c35, &i3);
-+ test_func_fix_var(5, &c35, &i5); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
-+ test_func_fix_uns(5, &c35, &i3);
-+ test_func_fix_uns(5, &c35, &i5); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
++ test_func_fix_fix(5, &c35, &i3, NULL);
++ test_func_fix_fix(5, &c35, &i5, NULL); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
++ test_func_fix_var(5, &c35, &i3, NULL);
++ test_func_fix_var(5, &c35, &i5, NULL); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
++ test_func_fix_uns(5, &c35, &i3, NULL);
++ test_func_fix_uns(5, &c35, &i5, NULL); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+}
+
void test_multidimensional_arrays() {
```
</details>
---
Full diff: https://github.com/llvm/llvm-project/pull/133333.diff
1 Files Affected:
- (modified) clang/test/C/C2y/n3369.c (+51-1)
``````````diff
diff --git a/clang/test/C/C2y/n3369.c b/clang/test/C/C2y/n3369.c
index 389828b52b6a2..db26040d8cf44 100644
--- a/clang/test/C/C2y/n3369.c
+++ b/clang/test/C/C2y/n3369.c
@@ -17,7 +17,11 @@
#error "Expected to have _Countof support"
#endif
+#define NULL ((void *) 0)
+
int global_array[12];
+int global_multi_array[12][34];
+int global_num;
void test_parsing_failures() {
(void)_Countof; // expected-error {{expected expression}}
@@ -36,6 +40,12 @@ void test_semantic_failures() {
expected-note {{forward declaration of 'struct S'}}
struct T { int x; };
(void)_Countof(struct T); // expected-error {{'_Countof' requires an argument of array type; 'struct T' invalid}}
+ struct U { int x[3]; };
+ (void)_Countof(struct U); // expected-error {{'_Countof' requires an argument of array type; 'struct U' invalid}}
+ int a[3];
+ (void)_Countof(&a); // expected-error {{'_Countof' requires an argument of array type; 'int (*)[3]' invalid}}
+ int *p;
+ (void)_Countof(p); // expected-error {{'_Countof' requires an argument of array type; 'int *' invalid}}
}
void test_constant_expression_behavior(int n) {
@@ -81,6 +91,22 @@ void test_with_function_param(int array[12], int (*array_ptr)[12], int static_ar
(void)_Countof(static_array); // expected-error {{'_Countof' requires an argument of array type; 'int *' invalid}}
}
+void test_func_fix_fix(int i, char (*a)[3][5], int (*x)[_Countof(*a)], char (*)[_Generic(x, int (*)[3]: 1)]); // expected-note {{passing argument to parameter}}
+void test_func_fix_var(int i, char (*a)[3][i], int (*x)[_Countof(*a)], char (*)[_Generic(x, int (*)[3]: 1)]); // expected-note {{passing argument to parameter}}
+void test_func_fix_uns(int i, char (*a)[3][*], int (*x)[_Countof(*a)], char (*)[_Generic(x, int (*)[3]: 1)]); // expected-note {{passing argument to parameter}}
+
+void test_funcs() {
+ int i3[3];
+ int i5[5];
+ char c35[3][5];
+ test_func_fix_fix(5, &c35, &i3, NULL);
+ test_func_fix_fix(5, &c35, &i5, NULL); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+ test_func_fix_var(5, &c35, &i3, NULL);
+ test_func_fix_var(5, &c35, &i5, NULL); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+ test_func_fix_uns(5, &c35, &i3, NULL);
+ test_func_fix_uns(5, &c35, &i5, NULL); // expected-warning {{incompatible pointer types passing 'int (*)[5]' to parameter of type 'int (*)[3]'}}
+}
+
void test_multidimensional_arrays() {
int array[12][7];
static_assert(_Countof(array) == 12);
@@ -102,6 +128,11 @@ void test_unspecified_array_length() {
static_assert(_Countof(**x) == 3);
}
+void test_completed_array() {
+ int a[] = {1, 2, global_num};
+ static_assert(_Countof(a) == 3);
+}
+
// Test that the return type of _Countof is what you'd expect (size_t).
void test_return_type() {
static_assert(_Generic(typeof(_Countof global_array), typeof(sizeof(0)) : 1, default : 0));
@@ -121,10 +152,14 @@ void test_typedefs() {
static_assert(_Countof(*x) == 12);
}
-void test_zero_size_arrays() {
+void test_zero_size_arrays(int n) {
int array[0]; // expected-warning {{zero size arrays are an extension}}
static_assert(_Countof(array) == 0);
static_assert(_Countof(int[0]) == 0); // expected-warning {{zero size arrays are an extension}}
+ int multi_array[0][n]; // FIXME: Should trigger -Wzero-length-array
+ static_assert(_Countof(multi_array) == 0);
+ int another_one[0][3]; // expected-warning {{zero size arrays are an extension}}
+ static_assert(_Countof(another_one) == 0);
}
void test_struct_members() {
@@ -144,3 +179,18 @@ void test_compound_literals() {
static_assert(_Countof((int[2]){}) == 2);
static_assert(_Countof((int[]){1, 2, 3, 4}) == 4);
}
+
+/* We don't get a diagnostic for test_f1(), because it ends up unused
+ * as _Countof() results in an integer constant expression, which is not
+ * evaluated. However, test_f2() ends up being evaluated, since 'a' is
+ * a VLA.
+ */
+static int test_f1();
+static int test_f2(); // FIXME: Should trigger function 'test_f2' has internal linkage but is not defined
+
+void test_symbols() {
+ int a[global_num][global_num];
+
+ static_assert(_Countof(global_multi_array[test_f1()]) == 34);
+ (void)_Countof(a[test_f2()]);
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/133333
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