From d8ef032e421c7485c8b2216ead65e5e23cab6b12 Mon Sep 17 00:00:00 2001
From: "Frank Ch. Eigler" <fche@redhat.com>
Date: Thu, 23 Apr 2015 21:33:18 -0400
Subject: [PATCH] session.cxx: improve parse error token colorization

Previous code had imperfect heuristics about cutting apart parts of
erroneous source lines, with a colorized token in the middle.  It
could occur that the token was synthetic, or cmd-line $/@ based,
in which case the srcline-cutting arithmetic could go off-end and
cause a basic_string::substr: exception.  New code dabbles less in
heuristics and confirms that the token content actually matches
the srcline content.  In case of a mismatch, the original srcline
around the token's location is transcribed verbatim (with ellipses).
---
 session.cxx | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/session.cxx b/session.cxx
index 587c77f1b..3753445cb 100644
--- a/session.cxx
+++ b/session.cxx
@@ -2117,18 +2117,29 @@ systemtap_session::print_error_source (std::ostream& message,
   //TRANSLATORS: Here we are printing the source string of the error
   message << align << _("source: ");
   string srcline = file_contents.substr(start_pos, end_pos-start_pos-1);
-  if (color_errors &&
-      // Only colorize tokens whose content is known to match the source
-      // content.  e.g. tok_string doesn't qualify because of the double-quotes.
-      // tok_embedded lacks the %{ %}. tok_junk is just junky.
-      (tok->type == tok_number ||
-       tok->type == tok_identifier || 
-       tok->type == tok_operator)) {
-    // Split into before token, token, and after token
-    string tok_content = tok->content;
-    message << srcline.substr(0, col-1);
-    message << colorize(tok_content, "token");
-    message << srcline.substr(col+tok_content.size()-1) << endl;
+  if (color_errors) {
+      // before token:
+      message << srcline.substr(0, col-1);
+      // token:
+      // after token:
+      // ... hold it - the token might have been synthetic,
+      // or expanded from a $@ command line argument, or ...
+      // so tok->content may have nothing in common with the
+      // contents of srcline at the same point.
+      string srcline_rest = srcline.substr(col-1);
+      string srcline_tokenish = srcline_rest.substr(0, tok->content.size());
+      if (srcline_tokenish == tok->content) { // oh good
+        message << colorize(tok->content, "token");
+        message << srcline_rest.substr(tok->content.size());
+        message << endl;
+      }
+      else { // oh bad
+        message << " ... ";
+        col += 5; // line up with the caret
+        message << colorize(tok->content, "token");
+        message << " ... " << srcline_rest;
+        message << endl;
+      }
   } else
     message << srcline << endl;
   message << align << "        ";
-- 
2.43.5