| Issue |
130652
|
| Summary |
clang: "function definition is not allowed here" when compiling GNU C with nested functions
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
carnivorecookies
|
The following code fails to compile on clang 20.1.0 (and earlier versions), but successfully compiles on GCC:
```c
#include <stdio.h>
int main() {
int foo() {
return 1;
}
printf("%d\n", foo());
}
```
with the following error:
```
<source>:4:12: error: function definition is not allowed here
4 | int foo() {
| ^
<source>:7:17: error: call to undeclared function 'foo'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
7 | printf("%d\n", foo());
| ^
2 errors generated.
```
even when using any of the GNU C standards (using any of the following compiler flags: `-std=gnu89`, `-std=gnu99`, `-std=gnu11`, `-std=gnu17`, and `-std=gnu23`)
according to the GNU website, nested functions are supported in GNU C:
<https://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html>
> A nested function is a function defined inside another function. **Nested functions are supported as an extension in GNU C, but are not supported by GNU C++.**
(emphasis added by me)
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