1232732 - fix MOZ_WIN_MEM_TRY_CATCH to work correctly with clang-cl

Status: RESOLVED FIXED

(Core :: General, defect)

Description

[Nathan Froyd [:froydnj]]

MOZ_WIN_MEM_TRY_CATCH contains:

  NS_WARNING("EXCEPTION_IN_PAGE_ERROR in " __FUNCTION__);

Requiring string concatenation here is apparently an MSVC extension.  LLVM's bug database has a WONTFIX bug against this:

https://llvm.org/bugs/show_bug.cgi?id=20013

Even though recent comments in the bug suggest that LLVM would accept a patch for this behavior ("seems difficult"), we should probably fix our code.  Deleting this NS_WARNING seems reasonable; making it use nsPrintfCString also seems reasonable.

This is the source of two files falling back to MSVC when compiling with clang-cl.  Fixing this would mean that all first-party Gecko code would work without falling back to MSVC.

Comment 1

[Nathan Froyd [:froydnj]]

Attachment: modify NS_WARNING in MOZ_WIN_MEM_TRY_CATCH

The particular syntax for this warning is an MSVC extension, which
causes clang-cl to fallback to MSVC when compiling files that use this
macro.  Trying to use nsPrintfCString or equivalent here runs into
issues of unused variables in non-debug builds.  I think it's reasonable
to raise an warning without a specific location; folks can grovel about
in a debugger if they want to figure out what's going on.

Comment 2

[(No longer employed by Mozilla) Aaron Klotz]

Comment on attachment 8703752 [details] [diff] [review]
modify NS_WARNING in MOZ_WIN_MEM_TRY_CATCH

Review of attachment 8703752 [details] [diff] [review]:
-----------------------------------------------------------------

Seems reasonable. I suppose another option is to define the macro differently depending on whether clang-cl is present. Either way is fine with me.

Comment 3

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c82bd0fbe6b6

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/c82bd0fbe6b6