We use GN's read_file to extract data from typemap files - perhaps analyze
overlooks this form of dependency?

What target(s) would you have expected to be affected? Do you see the typemaps as either build or data deps of them?

content should have been rebuilt.

Re data deps, I presumed that gn should figure this out automatically without having to list them in the gn files?

could this be similar to  bug 672244  or  bug 639328  ?

So yeah I'm guessing it's because the only dependency on these files is via
read_file calls. Typemapping is hard. mojom.gni reads (in the global scope)
every typemap file listed in the global bindings configurations (
https://cs.chromium.org/chromium/src/mojo/public/tools/bindings/mojom.gni?rcl=0ddb4374a9221dba28e9ea8a1edaacb32dcc0861&l=40
)

Then when processing a mojom target, we scan its list of source mojom files
to look for matches in the set of typemap entries (each typemap file
specifies the name of the mojom file it regards), and this is used to
inject additional metadata in the generated target(s) based on the active
typemap configuration for the target (chromium or blink).

If read_file dependencies don't translate to build dependencies given that
the contents of the read file can influence build behavior, that seems like
a bug?

One option could be to add any typemap files we use for a target, to the
set of inputs on its generation action, even though the typemap files
aren't actually used by the generator script.

It looks like those files are being read outside of any particular target or template, so GN wouldn't know what targets are actually affected by them.

(And no, this is unrelated to the grit issues).

I will fix this using magic.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ba3fc0dad59f9be26ce99f2aae4626cfc0330d2d

commit ba3fc0dad59f9be26ce99f2aae4626cfc0330d2d
Author: rockot <rockot@chromium.org>
Date: Mon Feb 13 17:58:25 2017

Mojo Bindings: Put typemap files in the build dependency tree

This ensures that any typemap configuration files used to configure an
internal type-mappings-generator target are included in that target's
set of inputs. Otherwise this dependency only comes in the form of
read_file() calls made outside of any target scope, and GN fails to
deduce the effect this has on mojom targets.

BUG= 691081 

Review-Url: https://codereview.chromium.org/2691483005
Cr-Commit-Position: refs/heads/master@{#450002}

[modify] https://crrev.com/ba3fc0dad59f9be26ce99f2aae4626cfc0330d2d/mojo/public/tools/bindings/blink_bindings_configuration.gni
[modify] https://crrev.com/ba3fc0dad59f9be26ce99f2aae4626cfc0330d2d/mojo/public/tools/bindings/chromium_bindings_configuration.gni
[modify] https://crrev.com/ba3fc0dad59f9be26ce99f2aae4626cfc0330d2d/mojo/public/tools/bindings/mojom.gni