tree 63140ca3737dd7aafa39f64365bd5175ad374f1c
parent 873422314254ef6186dea157d15d33cea29dd7bc
author Takuto Ikuta <tikuta@google.com> 1750323158 +0900
committer GN LUCI <gn-scoped@luci-project-accounts.iam.gserviceaccount.com> 1750325461 -0700

Propagate module dependencies transitively via public_deps

When using C++ modules, dependencies must be treated as transitive. If a
target `A` has a `public_deps` on module `B`, and `B` in turn has a
`public_deps` on module `C`, any target that depends on `A` must also be
provided with the dependency on `C`.

Previously, GN did not propagate these module dependencies recursively.
This meant the dependency on `C` was not passed to `A`'s dependents,
which could lead to compilation failures. This behavior is incorrect, as
dependencies between C++ modules are analogous to transitive header
inclusions.

This change fixes this by recursively traversing the `public_deps` graph
in `ResolvedTargetData` to collect the complete set of transitive module
dependencies. This ensures that all module dependencies are correctly
passed to the compiler.

Bug: 40440396
Change-Id: Ib7b0e09477705708c92e6981b651c0eb9d6617e3
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/19100
Reviewed-by: David Turner <digit@google.com>
Commit-Queue: Takuto Ikuta <tikuta@google.com>