https://bugs.llvm.org/show_bug.cgi?id=43696
Bug ID: 43696
Summary: wasm-ld satisfies weak external from archive
Product: lld
Version: unspecified
Hardware: Other
OS: other
Status: NEW
Severity: enhancement
Priority: P
Component: wasm
Assignee: unassignedb...@nondot.org
Reporter: dan433...@gmail.com
CC: llvm-bugs@lists.llvm.org, s...@chromium.org
wasm-ld (in LLVM 9.0) is pulling in symbols from an archive to satisfy weak
external references, which is different from what ELF linkers do, and precludes
a common use case.
Consider this testcase:
```c
#include <stdio.h>
extern int x __attribute__((weak));
int main(void) {
if (&x) {
printf("we have x: %d\n", x);
}
return 0;
}
```
This shouldn't cause `x` to be linked by itself, because `x` is weak, even if
`x` is available in an archive library. But if I create an archive library
containing this:
```c
int x = 42;
```
then `x` does get linked.
With the above snippets in a.c and b.c respectively, this command-line
reproduces the issue with wasi-sdk (clang configured to target wasm32 by
default):
$ clang -c b.c && llvm-ar crs b.a b.o && clang a.c b.a -Wl,-y,x
/tmp/a-5e48c9.o: reference to x
b.a: lazy definition of x
For comparison, on an ELF target, I get this:
$ clang -c b.c && llvm-ar crs b.a b.o && clang a.c b.a -Wl,-y,x
/tmp/a-4c66f3.o: reference to x
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