gclient: Make gclient_gn_args_file honor use_relative_paths

Without this repos that use the use_relative_paths still need to use
their absolute path for gclient_gn_args_file.

Bug: chromium:1102833
Change-Id: I470096625061a28abf495f4d1035121edbcd581f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2279874
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

gclient.py

@@ -427,6 +427,8 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     # The actual revision we ended up getting, or None if that information is
     # unavailable
     self._got_revision = None
+    # Whether this dependency should use relative paths.
+    self._use_relative_paths = False
 
     # recursedeps is a mutable value that selectively overrides the default
     # 'no recursion' setting on a dep-by-dep basis.
@@ -751,9 +753,9 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
     # (and therefore set self.relative on this Dependency object), then we
     # want to modify the deps and recursedeps by prepending the parent
     # directory of this dependency.
-    use_relative_paths = local_scope.get('use_relative_paths', False)
+    self._use_relative_paths = local_scope.get('use_relative_paths', False)
     rel_prefix = None
-    if use_relative_paths:
+    if self._use_relative_paths:
       rel_prefix = self.name
     elif self._relative:
       rel_prefix = os.path.dirname(self.name)
@@ -788,13 +790,13 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
 
     deps = local_scope.get('deps', {})
     deps_to_add = self._deps_to_objects(
-        self._postprocess_deps(deps, rel_prefix), use_relative_paths)
+        self._postprocess_deps(deps, rel_prefix), self._use_relative_paths)
 
     # compute which working directory should be used for hooks
     use_relative_hooks = local_scope.get('use_relative_hooks', False)
     hooks_cwd = self.root.root_dir
     if use_relative_hooks:
-      if not use_relative_paths:
+      if not self._use_relative_paths:
         raise gclient_utils.Error(
             'ParseDepsFile(%s): use_relative_hooks must be used with '
             'use_relative_paths' % self.name)
@@ -1036,7 +1038,13 @@ class Dependency(gclient_utils.WorkItem, DependencySettings):
       elif isinstance(value, basestring):
         value = gclient_eval.EvaluateCondition(value, variables)
       lines.append('%s = %s' % (arg, ToGNString(value)))
-    with open(os.path.join(self.root.root_dir, self._gn_args_file), 'wb') as f:
+
+    # When use_relative_paths is set, gn_args_file is relative to this DEPS
+    path_prefix = self.root.root_dir
+    if self._use_relative_paths:
+      path_prefix = self.name
+
+    with open(os.path.join(path_prefix, self._gn_args_file), 'wb') as f:
       f.write('\n'.join(lines).encode('utf-8', 'replace'))
 
   @gclient_utils.lockedmethod

testing_support/fake_repos.py

@@ -204,7 +204,7 @@ class FakeReposBase(object):
 
 class FakeRepos(FakeReposBase):
   """Implements populateGit()."""
-  NB_GIT_REPOS = 16
+  NB_GIT_REPOS = 17
 
   def populateGit(self):
     # Testing:
@@ -711,6 +711,19 @@ hooks = [{
       'relative.py': 'pass',
       'origin': 'git/repo_16@2\n'
     })
+    # A repo with a gclient_gn_args_file and use_relative_paths
+    self._commit_git('repo_17', {
+      'DEPS': textwrap.dedent("""\
+        use_relative_paths=True
+        vars = {
+          'toto': 'tata',
+        }
+        gclient_gn_args_file = 'repo17_gclient.args'
+        gclient_gn_args = [
+          'toto',
+        ]"""),
+      'origin': 'git/repo_17@2\n'
+    })
 
 class FakeRepoSkiaDEPS(FakeReposBase):
   """Simulates the Skia DEPS transition in Chrome."""

tests/gclient_git_smoketest.py

@@ -1395,6 +1395,16 @@ class GClientSmokeGIT(gclient_smoketest_base.GClientSmokeBase):
         '# ' + self.git_base + 'repo_14, DEPS',
     ], deps_contents.splitlines())
 
+  def testRelativeGNArgsFile(self):
+    self.gclient(['config', self.git_base + 'repo_17', '--name', 'src'])
+    self.gclient(['sync',])
+
+    tree = self.mangle_git_tree(('repo_17@1', 'src'))
+    tree['src/repo17_gclient.args'] = '\n'.join([
+        '# Generated from \'DEPS\'',
+        'toto = "tata"',
+    ])
+    self.assertTree(tree)
 
 if __name__ == '__main__':
   if '-v' in sys.argv: