Bug 206737 – [CMake] Provide a way to run a syntax check without actually compiling

• Component: Tools / Tests
• Status: ASSIGNED

[Adrian Perez]

The idea here would be to take advantage of the compilation
database (the “compile_commands.json” file which CMake can
generate when “-DCMAKE_EXPORT_COMPILE_COMMANDS=ON“ is passed
when configuring), pick the compiler commands from there,
and run them with “-fsyntax-only” added.

Now, there is a slight complication: many of the compilation
commands will need certain derived sources being generated
before they can successfully run. It would be good to have
a CMake target which depends on all the generated/derived
sources, so we can run “ninja derived-sources” (or similar)
and *then* run the “-fsyntax-only” checks.

[Adrian Perez]

Created attachment 388677 [details]
Very WIP Patch

[Adrian Perez]

(In reply to Adrian Perez from comment #1)
> Created attachment 388677 [details]
> Very WIP Patch

Some notes about this patch:

 - It does not add the target that prepares forwarding headers
   and derived sources. I have filed bug #206737 to do that
   separately.

 - This initial version of the patch predates bug #206597 and
   needs to be reworked a bit to take it into account.

Anyway, I think sharing it may help out get a feeling of what
I am trying to achieve here. The ultimate goal would be to see
if we can get to the point of having an EWS builder that can
quickly verify that a non-unified build would succeed.