Enable diagnostics color in GCC and Clang

4 files changed, 80 insertions, 2 deletions

diff --git a/libbuild2/cc/common.cxx b/libbuild2/cc/common.cxx
index 0af9531..c423c37 100644
--- a/libbuild2/cc/common.cxx
+++ b/libbuild2/cc/common.cxx
@@ -1609,5 +1609,54 @@ namespace build2
 
       return r;
     }
+
+    void common::
+    append_diag_color_options (cstrings& args) const
+    {
+      switch (cclass)
+      {
+      case compiler_class::msvc:
+        {
+          // Note: see init_diag logic if enabling anything here (probably
+          // need an "override disable" mode or some such).
+          //
+          break;
+        }
+      case compiler_class::gcc:
+        {
+          // Enable/disable diagnostics color unless a custom option is
+          // specified.
+          //
+          // Supported from GCC 4.9 and (at least) from Clang 3.5. Clang
+          // supports -f[no]color-diagnostics in addition to the GCC's
+          // spelling.
+          //
+          if (ctype == compiler_type::gcc   ? cmaj > 4 || (cmaj == 4 && cmin >= 9) :
+              ctype == compiler_type::clang ? cmaj > 3 || (cmaj == 3 && cmin >= 5) :
+              false)
+          {
+            if (!(find_option_prefix ("-fdiagnostics-color", args)        ||
+                  find_option        ("-fno-diagnostics-color", args)     ||
+                  find_option        ("-fdiagnostics-plain-output", args) ||
+                  (ctype == compiler_type::clang &&
+                   (find_option ("-fcolor-diagnostics", args) ||
+                    find_option ("-fno-color-diagnostics", args)))))
+            {
+              // Omit -fno-diagnostics-color if stderr is not a terminal (we
+              // know there will be no color in this case and the option will
+              // just add noise, for example, in build logs).
+              //
+              if (const char* o = (
+                    show_diag_color () ? "-fdiagnostics-color"    :
+                    stderr_term        ? "-fno-diagnostics-color" :
+                    nullptr))
+                args.push_back (o);
+            }
+          }
+
+          break;
+        }
+      }
+    }
   }
 }
diff --git a/libbuild2/cc/common.hxx b/libbuild2/cc/common.hxx
index 2a78fe0..c17db08 100644
--- a/libbuild2/cc/common.hxx
+++ b/libbuild2/cc/common.hxx
@@ -486,6 +486,11 @@ namespace build2
                       const dir_paths&,
                       const dir_paths&,
                       pair<bool, bool>) const;
+
+      // Append compiler-specific diagnostics color options as necessary.
+      //
+      void
+      append_diag_color_options (cstrings&) const;
     };
   }
 }
diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index 51d9b4d..e76cb7c 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -3214,8 +3214,8 @@ namespace build2
 
       // The gen argument to init_args() is in/out. The caller signals whether
       // to force the generated header support and on return it signals
-      // whether this support is enabled. The first call to init_args is
-      // expected to have gen false.
+      // whether this support is enabled. If gen is false, then stderr is
+      // expected to be either discarded or merged with sdtout.
       //
       // Return NULL if the dependency information goes to stdout and a
       // pointer to the temporary file path otherwise.
@@ -3404,6 +3404,9 @@ namespace build2
               append_options (args, cmode);
               append_sys_hdr_options (args); // Extra system header dirs (last).
 
+              // Note that for MSVC stderr is merged with stdout and is then
+              // parsed, so no append_diag_color_options() call.
+
               // See perform_update() for details on the choice of options.
               //
               {
@@ -3469,6 +3472,11 @@ namespace build2
                               cmode.size () - (modules && clang ? 1 : 0));
               append_sys_hdr_options (args); // Extra system header dirs (last).
 
+              // If not gen, then stderr is discarded.
+              //
+              if (gen)
+                append_diag_color_options (args);
+
               // See perform_update() for details on the choice of options.
               //
               if (!find_option_prefix ("-finput-charset=", args))
@@ -4929,6 +4937,9 @@ namespace build2
               append_options (args, cmode);
               append_sys_hdr_options (args);
 
+              // Note: no append_diag_color_options() call since the
+              // diagnostics is discarded.
+
               // See perform_update() for details on the choice of options.
               //
               {
@@ -4978,6 +4989,9 @@ namespace build2
                               cmode.size () - (modules && clang ? 1 : 0));
               append_sys_hdr_options (args);
 
+              // Note: no append_diag_color_options() call since the
+              // diagnostics is discarded.
+
               // See perform_update() for details on the choice of options.
               //
               if (!find_option_prefix ("-finput-charset=", args))
@@ -6883,6 +6897,10 @@ namespace build2
           if (md.pp != preprocessed::all)
             append_sys_hdr_options (args); // Extra system header dirs (last).
 
+          // Note: could be overridden in mode.
+          //
+          append_diag_color_options (args);
+
           // Set source/execution charsets to UTF-8 unless a custom charset
           // is specified.
           //
@@ -7026,6 +7044,10 @@ namespace build2
           if (md.pp != preprocessed::all)
             append_sys_hdr_options (args); // Extra system header dirs (last).
 
+          // Note: could be overridden in mode.
+          //
+          append_diag_color_options (args);
+
           // Set the input charset to UTF-8 unless a custom one is specified.
           //
           // Note that the execution charset (-fexec-charset) is UTF-8 by
diff --git a/libbuild2/cc/link-rule.cxx b/libbuild2/cc/link-rule.cxx
index 4588ce1..99aa421 100644
--- a/libbuild2/cc/link-rule.cxx
+++ b/libbuild2/cc/link-rule.cxx
@@ -3687,6 +3687,8 @@ namespace build2
             {
               ld = &cpath;
 
+              append_diag_color_options (args);
+
               // Add the option that triggers building a shared library and
               // take care of any extras (e.g., import library).
               //