1516758 - -Wodr: C++ One Definition Rule violations in Firefox

Status: UNCONFIRMED

(Firefox Build System :: General: Unsupported Platforms, defect, P5)

Description

[Jan Hubicka]

Attachment: odr.txt

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce:

I built Firefox with GCC 8 and LTO


Actual results:

I got warnings about ODR vilations


Expected results:

There should be no warnigs

Comment 1

[Sylvestre Ledru [:Sylvestre]]

Here is the kind of warnings:
/aux/hubicka/firefox-2018/release/security/ct/CTLogVerifier.h:29:7: warning: type ‘struct CTLogVerifier’ violates the C++ One Definition Rule [-Wodr]

Comment 2

[Jan Hubicka]

Note that the log I attached is produced by GCC9 where I made the warning hopefully more understandable.  Some of issues are easy to fix because they are caused by misplaced forward declarations that should be in proper name-space.  I will try to get around preparing patch for them.

Comment 3

[NicolasPacheco]

Hi! I am new here, how can I do to build Firefox with GCC 8 and LTO to replicate the warning?

Comment 4

[Kostadin Shishmanov]

Attachment: warnings

This is still reproducible, there are also some lto type mismatch warnings. see the attached log for more info.

Comment 5

[Sam James]

Note that these issues exist with Clang too, it's just that Clang doesn't diagnose them (doesn't have -Wodr or -Wlto-type-mismatch right now, I've filed bugs asking for them to support it).

Comment 6

[[:sergesanspaille]]

(Note that clang does have -Wodr but this flag really makes sense when merging compilation unit)

Comment 7

[Sam James]

(In reply to Sam James from comment #5)

Note that these issues exist with Clang too, it's just that Clang doesn't diagnose them (doesn't have -Wodr or -Wlto-type-mismatch right now, I've filed bugs asking for them to support it).

See https://github.com/llvm/llvm-project/issues/34914 (maskray also covers it on his blog at https://maskray.me/blog/2022-11-13-odr-violation-detection, but tl;dr is "only asan or C++ modules" and https://github.com/llvm/llvm-project/issues/56487.

Thank you for taking a look Serge!