From e3a05597ec42ed02230918fe0bcada3dbb521209 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 3 Jun 2021 12:48:56 +0300
Subject: Fix crashing on test command output regex match failure

---
 libbuild2/script/run.cxx | 58 +++++++++++++++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 16 deletions(-)

diff --git a/libbuild2/script/run.cxx b/libbuild2/script/run.cxx
index f36e979..46941734 100644
--- a/libbuild2/script/run.cxx
+++ b/libbuild2/script/run.cxx
@@ -644,33 +644,45 @@ namespace build2
           }
         }
 
-        // Create line regex.
+        // Issue regex error diagnostics and fail.
         //
-        line_regex regex;
-
-        try
-        {
-          regex = line_regex (move (rls), move (pool));
-        }
-        catch (const regex_error& e)
+        auto fail_regex = [&rl, &rd, &loc, &env, &output_info, &save_regex]
+                          (const regex_error& e, const string& what)
         {
-          // Note that line regex creation can not fail for here-string
-          // redirect as it doesn't have syntax line chars. That in
-          // particular means that end_line and end_column are meaningful.
+          const auto& ls (rl.lines);
+
+          // Note that the parser treats both empty here-string (for example
+          // >:~'') and empty here-document redirects as an error and so there
+          // should be at least one line in the list.
           //
-          assert (rd.type == redirect_type::here_doc_regex);
+          assert (!ls.empty ());
 
-          diag_record d (fail (loc (rd.end_line, rd.end_column)));
+          diag_record d (fail (rd.type == redirect_type::here_doc_regex
+                               ? loc (rd.end_line, rd.end_column)
+                               : loc (ls[0].line, ls[0].column)));
 
           // Print regex_error description if meaningful.
           //
-          d << "invalid " << what << " regex redirect" << e;
+          d << what << " regex redirect" << e;
 
           // It would be a waste to save the regex into the file just to
           // remove it.
           //
           if (env.temp_dir_keep)
             output_info (d, save_regex (), "", " regex");
+        };
+
+        // Create line regex.
+        //
+        line_regex regex;
+
+        try
+        {
+          regex = line_regex (move (rls), move (pool));
+        }
+        catch (const regex_error& e)
+        {
+          fail_regex (e, string ("invalid ") + what);
         }
 
         // Parse the output into the literal line string.
@@ -720,8 +732,22 @@ namespace build2
 
         // Match the output with the regex.
         //
-        if (regex_match (ls, regex)) // Doesn't throw.
-          return true;
+        // Note that we don't distinguish between the line_regex and
+        // char_regex match failures. While it would be convenient for the
+        // user if we provide additional information in the latter case (regex
+        // line number, etc), the implementation feels too hairy for now
+        // (would require to pull additional information into char_regex,
+        // etc). Though, we may want to implement it in the future.
+        //
+        try
+        {
+          if (regex_match (ls, regex))
+            return true;
+        }
+        catch (const regex_error& e)
+        {
+          fail_regex (e, string ("unable to match ") + what);
+        }
 
         // Output doesn't match the regex.
         //
-- 
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