1487477 - set COMPILE_FLAGS var to hide C++ warnings for Rust crates

Status: NEW

(Firefox Build System :: General, defect)

Description

[Myk Melez [:myk] [@mykmelez]]

The fix for regression bug 1482810 moves WARNINGS_CFLAGS into COMPILE_FLAGS and hides warnings generated by C code in Rust crates (by removing warnings flags from CFLAGS when compiling Rust libraries).

We should do the same thing for WARNINGS_CXXFLAGS, for the same reason: C++ code in Rust crates is invariably third-party code, and we generally aren't able to fix warnings in it, so it shouldn't clutter the build output for developers.

I tried to do that in my fix for bug 1482810, but I ran into some build failures that I couldn't figure out at the time.  The fix should be mostly similar to what I did in that bug, however.

And the upstream change that I needed to land in the cc crate observes both CFLAGS and CXXFLAGS to determine whether to enable warnings by default.  So it should be possible to hide C++ warnings without further upstream changes.

Comment 1

[Myk Melez [:myk] [@mykmelez]]

Attachment: set COMPILE_FLAGS var to hide C++ warnings for Rust crates

MozReview-Commit-ID: Lu0D4or8fCx

Comment 2

[Myk Melez [:myk] [@mykmelez]]

Here's a tryserver run with the WIP patch in https://bugzilla.mozilla.org/attachment.cgi?id=9005508:

https://treeherder.mozilla.org/#/jobs?repo=try&revision=37cfc42c1c4bf1184e0bd1531d4bdc2e59b892e6

Comment 3

[Kim Moir [:kmoir] ET]

Triaging, assigning to Myk since he attached patches.

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The bug assignee is inactive on Bugzilla, so the assignee is being reset.