<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/119953>119953</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang compiles an invalid program normally
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          ZY546
      </td>
    </tr>
</table>

<pre>
    https://godbolt.org/z/jETK87bq7
```c
int func_2();  //note: previous declaration of 'func_2' with type 'int(void)'
int func_1() { return func_2();}
int func_2(int a) { //error: conflicting types for 'func_2'; have 'int(int)'
    return 8;
}
int main() {
  return func_1();
}
```

Clang compiles the program normally, and the resulting program can be executed.


Expected behavior (like gcc):
```
Could not execute the program

Build failed

Compiler returned: 1
Compiler stderr

<source>:4:5: error: conflicting types for 'func_2'; have 'int(int)'
    4 | int func_2(int a) {
      | ^~~~~~
<source>:2:5: note: previous declaration of 'func_2' with type 'int(void)'
    2 | int func_2();
      |     ^~~~~~
```
</pre>
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