Issue #241 - handle depfiles generated by older versions of GCC

Older versions of GCC would produce broken depfiles when -MT or -MQ is used
    gcc43 -MT foo.o -MMD -MF foo.o.d -o foo.o -c foo.c
will result in the following depfile
    foo.o foo.o: <dependencies>

Parse multiple outputs unifying duplicates and correctly report errors if
they are different.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/depfile_parser_test.cc b/src/depfile_parser_test.cc
index 43e677c..883926a 100644
--- a/src/depfile_parser_test.cc
+++ b/src/depfile_parser_test.cc
@@ -102,3 +102,20 @@ TEST_F(DepfileParserTest, Escapes) {
             parser_.out_.AsString());
   ASSERT_EQ(0u, parser_.ins_.size());
 }
+
+TEST_F(DepfileParserTest, UnifyMultupleOutputs) {
+  // check that multiple duplicate targets are properly unified
+  string err;
+  EXPECT_TRUE(Parse("foo foo: x y z", &err));
+  ASSERT_EQ(parser_.out_.AsString(), "foo");
+  ASSERT_EQ(parser_.ins_.size(), 3);
+  EXPECT_EQ("x", parser_.ins_[0].AsString());
+  EXPECT_EQ("y", parser_.ins_[1].AsString());
+  EXPECT_EQ("z", parser_.ins_[2].AsString());
+}
+
+TEST_F(DepfileParserTest, RejectMultipleDifferentOutputs) {
+  // check that multiple different outputs are rejected by the parser
+  string err;
+  EXPECT_FALSE(Parse("foo bar: x y z", &err));
+}