1604863 - mk_add_options in .mozconfig has unintuitive behavior

Status: NEW

(Firefox Build System :: General, enhancement, P3)

Description

[Ricky Stewart]

mk_add_options doesn't work as people would expect it to intuitively; this is an issue most recently raised in bug 1603860. We currently don't have any safeguards in place to protect users from breaking themselves like this.

Unfortunately, the nature of the feature and its implementation means that mk_add_options will behave as users intuitively expect it to sometimes but break in odd ways other times.

Unfortunately our public documentation suggests using mk_add_options in places: https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Configuring_Build_Options

Addressing this bug fully can include adding additional errors/warning messages when someone attempts to set a variable with mk_add_options that we know is broken as well as deprecating and removing mk_add_options completely.

This is related to the unresolved bug 1413294 and bug 1089911.

Comment 1

[Ricky Stewart]

Updated the bug and the description to remove references to setting a compiler with "export" (i.e. export CC=clang-8) which actually seems to work fine. The text of the bug still applies to mk_add_options though.