Add --[no]diag-color options (infrastructure only)

6 files changed, 96 insertions, 19 deletions

diff --git a/bdep/bdep.cxx b/bdep/bdep.cxx
index 3061650..73c1302 100644
--- a/bdep/bdep.cxx
+++ b/bdep/bdep.cxx
@@ -6,6 +6,7 @@
 #endif
 
 #include <limits>
+#include <cstdlib>     // getenv()
 #include <cstring>     // strcmp()
 #include <iostream>
 #include <exception>   // set_terminate(), terminate_handler
@@ -281,31 +282,47 @@ init (const common_options& co,
 
     // Verify common options.
     //
-    // Also merge the --progress/--no-progress options, overriding a less
-    // specific flag with a more specific.
+    // Also merge the --*/--no-* options, overriding a less specific flag with
+    // a more specific.
     //
-    optional<bool> progress;
-    auto merge_progress = [&progress]
-                          (const O& o,
-                           const default_options_entry<O>* e = nullptr)
+    optional<bool> progress, diag_color;
+    auto merge_no = [&progress, &diag_color] (
+      const O& o,
+      const default_options_entry<O>* e = nullptr)
     {
-      if (o.progress () && o.no_progress ())
       {
-        diag_record dr;
-        (e != nullptr ? dr << fail (e->file) : dr << fail)
+        if (o.progress () && o.no_progress ())
+        {
+          diag_record dr;
+          (e != nullptr ? dr << fail (e->file) : dr << fail)
           << "both --progress and --no-progress specified";
+        }
+
+        if (o.progress ())
+          progress = true;
+        else if (o.no_progress ())
+          progress = false;
       }
 
-      if (o.progress ())
-        progress = true;
-      else if (o.no_progress ())
-        progress = false;
+      {
+        if (o.diag_color () && o.no_diag_color ())
+        {
+          diag_record dr;
+          (e != nullptr ? dr << fail (e->file) : dr << fail)
+          << "both --diag-color and --no-diag-color specified";
+        }
+
+        if (o.diag_color ())
+          diag_color = true;
+        else if (o.no_diag_color ())
+          diag_color = false;
+      }
     };
 
     for (const default_options_entry<O>& e: dos)
-      merge_progress (e.options, &e);
+      merge_no (e.options, &e);
 
-    merge_progress (o);
+    merge_no (o);
 
     o = merge_options (dos, o);
 
@@ -314,6 +331,12 @@ init (const common_options& co,
       o.progress (*progress);
       o.no_progress (!*progress);
     }
+
+    if (diag_color)
+    {
+      o.diag_color (*diag_color);
+      o.no_diag_color (!*diag_color);
+    }
   }
   catch (const invalid_argument& e)
   {
@@ -368,7 +391,23 @@ try
 
   default_terminate = set_terminate (custom_terminate);
 
-  stderr_term = fdterm (stderr_fd ());
+  if (fdterm (stderr_fd ()))
+  {
+    stderr_term = std::getenv ("TERM");
+
+    stderr_term_color =
+#ifdef _WIN32
+      // For now we disable color on Windows since it's unclear if/where/how
+      // it is supported. Maybe one day someone will figure this out.
+      //
+      false
+#else
+      // This test was lifted from GCC (Emacs shell sets TERM=dumb).
+      //
+      *stderr_term != nullptr && strcmp (*stderr_term, "dumb") != 0
+#endif
+      ;
+  }
 
   argv0 = argv[0];
   exec_dir = path (argv0).directory ();
diff --git a/bdep/common.cli b/bdep/common.cli
index ed7a901..a90794b 100644
--- a/bdep/common.cli
+++ b/bdep/common.cli
@@ -122,6 +122,18 @@ namespace bdep
        network transfers, building, etc."
     }
 
+    bool --diag-color
+    {
+      "Use color in diagnostics. If printing to a terminal the color is used
+       by default provided the terminal is not dumb. Use \cb{--no-diag-color}
+       to suppress."
+    }
+
+    bool --no-diag-color
+    {
+      "Don't use color in diagnostics."
+    }
+
     path --bpkg
     {
       "<path>",
diff --git a/bdep/sync.cxx b/bdep/sync.cxx
index 8140426..0cda5af 100644
--- a/bdep/sync.cxx
+++ b/bdep/sync.cxx
@@ -1861,6 +1861,7 @@ namespace bdep
                  << "    run '" << argv0 << "' sync --hook=1 "         <<
                 "--verbose $build.verbosity "                          <<
                 "($build.progress == [null] ? : $build.progress ? --progress : --no-progress) " <<
+                "($build.diag_color == [null] ? : $build.diag_color ? --diag-color : --no-diag-color) " <<
                 "--config \"$out_root\""                               << endl
                  << "}"                                                << endl;
 
diff --git a/bdep/utility.cxx b/bdep/utility.cxx
index 01456eb..3d97090 100644
--- a/bdep/utility.cxx
+++ b/bdep/utility.cxx
@@ -80,7 +80,8 @@ namespace bdep
     }
   }
 
-  bool stderr_term;
+  optional<const char*> stderr_term = nullopt;
+  bool stderr_term_color = false;
 
   dir_path
   current_directory ()
diff --git a/bdep/utility.hxx b/bdep/utility.hxx
index f5b0412..c7d4666 100644
--- a/bdep/utility.hxx
+++ b/bdep/utility.hxx
@@ -143,9 +143,17 @@ namespace bdep
     return move (normalize (r, what));
   }
 
-  // Progress.
+  // Diagnostics.
   //
-  extern bool stderr_term; // True if stderr is a terminal.
+  // If stderr is not a terminal, then the value is absent (so can be used as
+  // bool). Otherwise, it is the value of the TERM environment variable (which
+  // can be NULL).
+  //
+  extern optional<const char*> stderr_term;
+
+  // True if the color can be used on the stderr terminal.
+  //
+  extern bool stderr_term_color;
 
   // Filesystem.
   //
diff --git a/bdep/utility.txx b/bdep/utility.txx
index 100ee07..a7d060d 100644
--- a/bdep/utility.txx
+++ b/bdep/utility.txx
@@ -121,6 +121,14 @@ namespace bdep
           ops.push_back ("--no-progress");
       }
 
+      // Forward our --[no]diag-color options.
+      //
+      if (co.diag_color ())
+        ops.push_back ("--diag-color");
+
+      if (co.no_diag_color ())
+        ops.push_back ("--no-diag-color");
+
       // Forward our --build* options.
       //
       if (co.build_specified ())
@@ -236,6 +244,14 @@ namespace bdep
           ops.push_back ("--no-progress");
       }
 
+      // Forward our --[no]diag-color options.
+      //
+      if (co.diag_color ())
+        ops.push_back ("--diag-color");
+
+      if (co.no_diag_color ())
+        ops.push_back ("--no-diag-color");
+
       return process_start_callback (
         [v] (const char* const args[], size_t n)
         {