Correct gn path rebasing for object files located inside build direct…

…ory.

BUG=none

Review URL: https://codereview.chromium.org/262143003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@268372 0039d316-1c4b-4281-b951-d872f2087c98

tools/gn/ninja_helper.cc

@@ -5,6 +5,7 @@
 #include "tools/gn/ninja_helper.h"
 
 #include "base/logging.h"
+#include "base/strings/string_util.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/string_utils.h"
 #include "tools/gn/target.h"
@@ -93,6 +94,20 @@ OutputFile NinjaHelper::GetOutputFileForSource(
       if (source.is_system_absolute())
         return OutputFile(source.value());
 
+      // Files that are already inside the build dir should not be made
+      // relative to the source tree. Doing so will insert an unnecessary
+      // "../.." into the path which won't match the corresponding target
+      // name in ninja.
+      CHECK(build_settings_->build_dir().is_source_absolute());
+      CHECK(source.is_source_absolute());
+      if (StartsWithASCII(source.value(),
+                          build_settings_->build_dir().value(),
+                          true)) {
+        return OutputFile(
+            source.value().substr(
+                build_settings_->build_dir().value().size()));
+      }
+
       // Construct the relative location of the file from the build dir.
       OutputFile ret(build_to_src_no_last_slash());
       source.SourceAbsoluteWithOneSlash().AppendToString(&ret.value());

tools/gn/ninja_helper_unittest.cc

@@ -24,7 +24,7 @@ class HelperSetterUpper {
     settings.set_target_os(Settings::WIN);
 
     // Output going to "out/Debug".
-    build_settings.SetBuildDir(SourceDir("/out/Debug/"));
+    build_settings.SetBuildDir(SourceDir("//out/Debug/"));
 
     // Our source target is in "tools/gn".
     target.set_output_type(Target::EXECUTABLE);
@@ -58,6 +58,32 @@ TEST(NinjaHelper, GetOutputFileForSource) {
                                           SOURCE_CC).value());
 }
 
+TEST(NinjaHelper, GetOutputFileForObject) {
+  HelperSetterUpper setup;
+  NinjaHelper helper(&setup.build_settings);
+
+  EXPECT_EQ(OutputFile("../../tools/gn/foo.o").value(),
+            helper.GetOutputFileForSource(&setup.target,
+                                          SourceFile("//tools/gn/foo.o"),
+                                          SOURCE_O).value());
+
+  EXPECT_EQ(OutputFile("../../tools/gn/foo.obj").value(),
+            helper.GetOutputFileForSource(&setup.target,
+                                          SourceFile("//tools/gn/foo.obj"),
+                                          SOURCE_O).value());
+
+  EXPECT_EQ(OutputFile("nested/foo.o").value(),
+            helper.GetOutputFileForSource(
+                &setup.target,
+                SourceFile("//out/Debug/nested/foo.o"),
+                SOURCE_O).value());
+
+  EXPECT_EQ(OutputFile("/abs/rooted/foo.o").value(),
+            helper.GetOutputFileForSource(&setup.target,
+                                          SourceFile("/abs/rooted/foo.o"),
+                                          SOURCE_O).value());
+}
+
 TEST(NinjaHelper, GetTargetOutputFile) {
   HelperSetterUpper setup;
   NinjaHelper helper(&setup.build_settings);