[LLD][COFF] Mark operator== const to avoid ambiguity in C++20.

[bazuzi]

C++20 will automatically generate an operator== with reversed operand order, which is ambiguous with the written operator== when one argument is marked const and the other isn't.

[llvmbot]

@llvm/pr-subscribers-platform-windows

@llvm/pr-subscribers-lld

Changes

C++20 will automatically generate an operator== with reversed operand order, which is ambiguous with the written operator== when one argument is marked const and the other isn't.

---

Full diff: https://github.com/llvm/llvm-project/pull/68119.diff

1 Files Affected:

• (modified) lld/COFF/Config.h (+1-1)

diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
index e66ab3a32c56721..ff87eab2744dd51 100644
--- a/lld/COFF/Config.h
+++ b/lld/COFF/Config.h
@@ -72,7 +72,7 @@ struct Export {
   StringRef symbolName;
   StringRef exportName; // Name in DLL
 
-  bool operator==(const Export &e) {
+  bool operator==(const Export &e) const {
     return (name == e.name && extName == e.extName &&
             aliasTarget == e.aliasTarget &&
             ordinal == e.ordinal && noname == e.noname &&

[bazuzi]

@mstorsjo I don't have write access, so can't specifically add reviewers, but I see that you reviewed the last change touching this file. Would you be able to take a look at this small change?

[aganea]

C++20 will automatically generate an operator== with reversed operand order, which is ambiguous with the written operator== when one argument is marked const and the other isn't.

You mean when building LLD with cmake ... -DCMAKE_CXX_STANDARD=20?

[aganea]

I reproduced the issue, thanks for the fix! LGTM. I can merge the change if there are no further objections from @mstorsjo

[bazuzi]

Thanks!

[mstorsjo]

I reproduced the issue, thanks for the fix! LGTM. I can merge the change if there are no further objections from @mstorsjo

No objection from me, this seems straightforward to me. Thanks for the patch, and thanks for reviewing it!