Improve location of error messages around identifiers.

Lexer::ReadIdent() now sets last_token_ before returning, like
Lexer::ReadEvalString() does. So all "expected identifiers" and things
that call ReadIdent (pool parser, rule parser, let parser, code parsing
the rule name after a : in a build line) now point the "^ near here" at
what was there instead of the previous last_token

According to manifest_parser_perftest, this is perf-neutral.

3 files changed, 27 insertions, 9 deletions

diff --git a/src/lexer.cc b/src/lexer.cc
index 37b8678..49c69aa 100644
--- a/src/lexer.cc
+++ b/src/lexer.cc
@@ -537,8 +537,9 @@ yy92:
 
 bool Lexer::ReadIdent(string* out) {
   const char* p = ofs_;
+  const char* start;
   for (;;) {
-    const char* start = p;
+    start = p;
     
 {
 	unsigned char yych;
@@ -604,7 +605,10 @@ yy96:
     }
 yy97:
 	++p;
-	{ return false; }
+	{
+      last_token_ = start;
+      return false;
+    }
 yy99:
 	++p;
 	yych = *p;
@@ -616,6 +620,7 @@ yy100:
 }
 
   }
+  last_token_ = start;
   ofs_ = p;
   EatWhitespace();
   return true;
diff --git a/src/lexer.in.cc b/src/lexer.in.cc
index f861239..20ed442 100644
--- a/src/lexer.in.cc
+++ b/src/lexer.in.cc
@@ -182,16 +182,21 @@ void Lexer::EatWhitespace() {
 
 bool Lexer::ReadIdent(string* out) {
   const char* p = ofs_;
+  const char* start;
   for (;;) {
-    const char* start = p;
+    start = p;
     /*!re2c
     varname {
       out->assign(start, p - start);
       break;
     }
-    [^] { return false; }
+    [^] {
+      last_token_ = start;
+      return false;
+    }
     */
   }
+  last_token_ = start;
   ofs_ = p;
   EatWhitespace();
   return true;
diff --git a/src/manifest_parser_test.cc b/src/manifest_parser_test.cc
index 39ed810..c91d8d1 100644
--- a/src/manifest_parser_test.cc
+++ b/src/manifest_parser_test.cc
@@ -523,7 +523,7 @@ TEST_F(ParserTest, Errors) {
     EXPECT_FALSE(parser.ParseTest("build x: y z\n", &err));
     EXPECT_EQ("input:1: unknown build rule 'y'\n"
               "build x: y z\n"
-              "       ^ near here"
+              "         ^ near here"
               , err);
   }
 
@@ -534,7 +534,7 @@ TEST_F(ParserTest, Errors) {
     EXPECT_FALSE(parser.ParseTest("build x:: y z\n", &err));
     EXPECT_EQ("input:1: expected build command name\n"
               "build x:: y z\n"
-              "       ^ near here"
+              "        ^ near here"
               , err);
   }
 
@@ -636,7 +636,10 @@ TEST_F(ParserTest, Errors) {
     string err;
     EXPECT_FALSE(parser.ParseTest("rule %foo\n",
                                   &err));
-    EXPECT_EQ("input:1: expected rule name\n", err);
+    EXPECT_EQ("input:1: expected rule name\n"
+              "rule %foo\n"
+              "     ^ near here",
+              err);
   }
 
   {
@@ -672,7 +675,10 @@ TEST_F(ParserTest, Errors) {
     string err;
     EXPECT_FALSE(parser.ParseTest("rule cc\n  command = foo\n  && bar",
                                   &err));
-    EXPECT_EQ("input:3: expected variable name\n", err);
+    EXPECT_EQ("input:3: expected variable name\n"
+              "  && bar\n"
+              "  ^ near here",
+              err);
   }
 
   {
@@ -767,7 +773,9 @@ TEST_F(ParserTest, Errors) {
     ManifestParser parser(&local_state, NULL);
     string err;
     EXPECT_FALSE(parser.ParseTest("pool\n", &err));
-    EXPECT_EQ("input:1: expected pool name\n", err);
+    EXPECT_EQ("input:1: expected pool name\n"
+              "pool\n"
+              "    ^ near here", err);
   }
 
   {