Fix GN action target writing with no sources list.

tools/gn/substitution_writer.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/substitution_writer.h"
 
 #include "tools/gn/build_settings.h"
 #include "tools/gn/escape.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/output_file.h"
@@ skipping 107 matching lines @@
     "    //out/Debug/obj/mydirectory/input2.h\n"
     "    //out/Debug/obj/mydirectory/input2.cc\n";
 
 SubstitutionWriter::SubstitutionWriter() {
 }
 
 SubstitutionWriter::~SubstitutionWriter() {
 }
 
 // static
+void SubstitutionWriter::GetListAsSourceFiles(
+    const Settings* settings,
+    const SubstitutionList& list,
+    std::vector<SourceFile>* output) {
+  for (size_t i = 0; i < list.list().size(); i++) {
+    const SubstitutionPattern& pattern = list.list()[i];
+    CHECK(pattern.ranges().size() == 1 &&
+          pattern.ranges()[0].type == SUBSTITUTION_LITERAL)
+        << "The substitution patterm \""
+        << pattern.AsString()
+        << "\" was expected to be a literal with no {{substitutions}}.";
+    const std::string& literal = pattern.ranges()[0].literal;
+    CHECK(literal.size() >= 1 && literal[0] == '/')
+        << "The result of the pattern \""
+        << pattern.AsString()
+        << "\" was not an absolute path.";
+    output->push_back(SourceFile(literal));
+  }
+}
+
+void SubstitutionWriter::GetListAsOutputFiles(
+    const Settings* settings,
+    const SubstitutionList& list,
+    std::vector<OutputFile>* output) {
+  std::vector<SourceFile> output_as_sources;
+  GetListAsSourceFiles(settings, list, &output_as_sources);
+  for (size_t i = 0; i < output_as_sources.size(); i++) {
+    output->push_back(OutputFile(
+        RebaseSourceAbsolutePath(output_as_sources[i].value(),
+                                 settings->build_settings()->build_dir())));
+  }
+}
+
+// static
 SourceFile SubstitutionWriter::ApplyPatternToSource(
       const Settings* settings,
       const SubstitutionPattern& pattern,
       const SourceFile& source) {
   std::string result_value;
   for (size_t i = 0; i < pattern.ranges().size(); i++) {
     const SubstitutionPattern::Subrange& subrange = pattern.ranges()[i];
     if (subrange.type == SUBSTITUTION_LITERAL) {
       result_value.append(subrange.literal);
     } else {
@@ skipping 170 matching lines @@
       return std::string();
   }
 
   // If we get here, the result is a path that should be made relative or
   // absolute according to the output_style. Other cases (just file name or
   // extension extraction) will have been handled via early return above.
   if (output_style == OUTPUT_ABSOLUTE)
     return to_rebase;
   return RebaseSourceAbsolutePath(to_rebase, relative_to);
 }