xpcom/string/precompiled_templates.cpp doesn't build with unified build disabled. I get lots of errors such if I disable unified build, such as: 0:01.69 /home/cpearce/src/firefox/xpcom/string/precompiled_templates.cpp: In instantiation of 'int Compare(const mozilla::detail::nsTStringRepr<CharT>&, const mozilla::detail::nsTStringRepr<CharT>&, const nsTStringComparator<T>&) [with T = char]': 0:01.69 /home/cpearce/src/firefox/xpcom/string/precompiled_templates.cpp:55:47: required from here 0:01.70 /home/cpearce/src/firefox/xpcom/string/precompiled_templates.cpp:55:47: error: explicit instantiation of 'int Compare(const mozilla::detail::nsTStringRepr<CharT>&, const mozilla::detail::nsTStringRepr<CharT>&, const nsTStringComparator<T>&) [with T = char]' but no definition available [-fpermissive] Full error log attached. I'm building on Linux with gcc (Ubuntu 6.3.0-12ubuntu2) 6.3.0 20170406.

I see this on clang builds for Android (bug 1163171, in progress) too.

Ah, this is because of NS_FASTCALL mismatches.

The template declaration and definition of Compare use NS_FASTCALL, while the explicit instantiation of Compare does not, which produces complaints from newer compilers. Add NS_FASTCALL to the explicit instantiation so that things match up. My Android x86 build on try seems happy with this change.

Comment on attachment 8907786 [details] [diff] [review] declare explicit instantiations of Compare as NS_FASTCALL Review of attachment 8907786 [details] [diff] [review]: ----------------------------------------------------------------- Thanks for tracking this down Nathan.

Pushed by nfroyd@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/93d73e654498 declare explicit instantiations of Compare as NS_FASTCALL; r=erahm