https://sourceware.org/bugzilla/show_bug.cgi?id=31956
--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Sam James from comment #6)
> (In reply to Sam James from comment #5)
>
> Here's a failing runtime test case with the patch.
>
> tls_crypt_testdriver-buffer.c:
> ```
> void buffer_write_file(void) {
> __builtin_printf("Called real buffer_write_file :(\n");
> __builtin_abort();
> }
> ```
>
> tls_crypt_testdriver-crypto.c:
> ```
> void buffer_write_file(void);
>
> void write_pem_key_file(const char *filename, const char *key_name) {
> buffer_write_file();
> }
> ```
>
> tls_crypt_testdriver-test_tls_crypt.c:
> ```
> void write_pem_key_file(const char *filename, const char *key_name);
>
> void __wrap_buffer_write_file(void) {
> __builtin_printf("Called wrapped buffer_write_file :)\n");
> }
>
> void test_tls_crypt_v2_write_server_key_file(void) {
> write_pem_key_file("testfilename.key", "OpenVPN tls-crypt-v2 server key");
> }
>
> int main() {
> test_tls_crypt_v2_write_server_key_file();
> }
> ```
>
> gcc -Og -flto -Wl,--wrap=buffer_write_file -o tls_crypt_testdriver
> tls_crypt_testdriver-test_tls_crypt.c tls_crypt_testdriver-buffer.cc
> tls_crypt_testdriver-crypto.c
>
> It passes with lld but fails with mold and bfd.
I don't think this testcase is valid. LTO knows nothing about symbol wrap.
When
LTO sees a buffer_write_file call, it can inline it. To support symbol wrap,
the
original definition, buffer_write_file, shouldn't be visible to LTO.
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