Add an opt-in flag to make duplicate edges an error (`-w dupbuild=err`).

This is step 1 on #931.  Duplicated edges will become an error by default in
the future.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/manifest_parser.h b/src/manifest_parser.h
index 00a711d..f72cd6f 100644
--- a/src/manifest_parser.h
+++ b/src/manifest_parser.h
@@ -32,10 +32,11 @@ struct ManifestParser {
     virtual bool ReadFile(const string& path, string* content, string* err) = 0;
   };
 
-  ManifestParser(State* state, FileReader* file_reader);
+  ManifestParser(State* state, FileReader* file_reader,
+                 bool dupe_edge_should_err = false);
 
   /// Load and parse a file.
-  bool Load(const string& filename, string* err, Lexer* parent=NULL);
+  bool Load(const string& filename, string* err, Lexer* parent = NULL);
 
   /// Parse a text string of input.  Used by tests.
   bool ParseTest(const string& input, string* err) {
@@ -65,6 +66,7 @@ private:
   BindingEnv* env_;
   FileReader* file_reader_;
   Lexer lexer_;
+  bool dupe_edge_should_err_;
   bool quiet_;
 };