<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - error in backend: Prototypeless function used with conflicting signatures"
   href="https://bugs.llvm.org/show_bug.cgi?id=40472">40472</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>error in backend: Prototypeless function used with conflicting signatures
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Backend: WebAssembly
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>alonzakai@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>STR: a.c is

===
#include <stdio.h>
int main()
{
    printf("hello %d\n", strnlen("waka", 2)); // Implicit declaration, no
header, for strnlen
    int (*my_strnlen)(char*, ...) = strnlen;
    printf("hello %d\n", my_strnlen("shaka", 2));
    return 0;
}
===

Build with

./emcc a.c -Wno-implicit-function-declaration

Output is

===
a.c:5:11: warning: incompatible pointer types initializing 'int (*)(char *,
...)' with an expression of type 'int ()' [-Wincompatible-pointer-types]
    int (*my_strnlen)(char*, ...) = strnlen;
          ^                         ~~~~~~~
fatal error: error in backend: Prototypeless function used with conflicting
signatures: strnlen
clang-8: error: clang frontend command failed with exit code 70 (use -v to see
invocation)
clang version 9.0.0 (<a href="mailto:git@github.com">git@github.com</a>:llvm-mirror/clang.git
0a4307de1174f61c465c94111f8376d3f5ed548e) (<a href="mailto:git@github.com">git@github.com</a>:llvm-mirror/llvm.git
74ebd8a99755a5e0e1c14001de05fc089f0ee28f)
Target: wasm32-unknown-unknown-wasm
===

(The warning is correct.)</pre>
        </div>
      </p>


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