From b6050ea38d01374e1c18809f4b5ff6f7d302a122 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Fri, 18 Jun 2021 05:45:02 -0400
Subject: [PATCH] c++: add color to function decl printing
To: gcc-patches@gcc.gnu.org

In reading C++ diagnostics, it's often hard to find the name of the function
in the middle of the template header, return type, parameters, and template
arguments.  So let's colorize it, and maybe the template argument bindings
while we're at it.

I've somewhat arbitrarily chosen bold green for the function name, and
non-bold magenta for the template arguments.

A side-effect of this is that when this happens in a quote (i.e. %qD), the
rest of the quote after the function name is no longer bold.  I think that's
acceptable; returning to the bold would require maintaining a colorize stack
instead of the on/off controls we have now.

gcc/cp/ChangeLog:

	* error.c (decl_to_string): Add show_color parameter.
	(subst_to_string): Likewise.
	(cp_printer): Pass it.
	(type_to_string): Set pp_show_color.
	(dump_function_name): Use "fnname" color.
	(dump_template_bindings): Use "targs" color.
	(struct colorize_guard): New.
	(reinit_cxx_pp): Clear pp_show_color.
	(cp_print_error_function): Use %qD.
	(function_category): Use %qD.

gcc/ChangeLog:

	* diagnostic-color.c: Add fnname and targs color entries.
	* doc/invoke.texi: Document them.
---
 gcc/doc/invoke.texi    |  8 +++++
 gcc/cp/error.c         | 70 ++++++++++++++++++++++++++++++------------
 gcc/diagnostic-color.c |  2 ++
 3 files changed, 60 insertions(+), 20 deletions(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 9b4371b9213..cdfddd75343 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -4803,6 +4803,14 @@ SGR substring for location information, @samp{file:line} or
 @vindex quote GCC_COLORS @r{capability}
 SGR substring for information printed within quotes.
 
+@item fnname=
+@vindex fnname GCC_COLORS @r{capability}
+SGR substring for names of C++ functions.
+
+@item targs=
+@vindex targs GCC_COLORS @r{capability}
+SGR substring for C++ function template parameter bindings.
+
 @item fixit-insert=
 @vindex fixit-insert GCC_COLORS @r{capability}
 SGR substring for fix-it hints suggesting text to
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 323643d1e6f..0008ee2ee8d 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -1,4 +1,4 @@
-/* Call-backs for C++ error reporting.
+/* Call-backs for -*- C++ -*- error reporting.
    This code is non-reentrant.
    Copyright (C) 1993-2021 Free Software Foundation, Inc.
    This file is part of GCC.
@@ -25,6 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "cp-tree.h"
 #include "stringpool.h"
 #include "tree-diagnostic.h"
+#include "diagnostic-color.h"
 #include "langhooks-def.h"
 #include "intl.h"
 #include "cxx-pretty-print.h"
@@ -56,7 +57,7 @@ static cxx_pretty_printer * const cxx_pp = &actual_pretty_printer;
 static const char *args_to_string (tree, int);
 static const char *code_to_string (enum tree_code);
 static const char *cv_to_string (tree, int);
-static const char *decl_to_string (tree, int);
+static const char *decl_to_string (tree, int, bool);
 static const char *fndecl_to_string (tree, int);
 static const char *op_to_string	(bool, enum tree_code);
 static const char *parm_to_string (int);
@@ -390,6 +391,7 @@ dump_template_bindings (cxx_pretty_printer *pp, tree parms, tree args,
       else
 	{
 	  pp_cxx_whitespace (pp);
+	  pp_string (pp, colorize_start (pp_show_color (pp), "targs"));
 	  pp_cxx_left_bracket (pp);
 	  pp->translate_string ("with");
 	  pp_cxx_whitespace (pp);
@@ -400,7 +402,10 @@ dump_template_bindings (cxx_pretty_printer *pp, tree parms, tree args,
     ~prepost_semicolon ()
     {
       if (need_semicolon)
-	pp_cxx_right_bracket (pp);
+	{
+	  pp_cxx_right_bracket (pp);
+	  pp_string (pp, colorize_stop (pp_show_color (pp)));
+	}
     }
   } semicolon_or_introducer = {pp, false};
 
@@ -1158,6 +1163,22 @@ dump_simple_decl (cxx_pretty_printer *pp, tree t, tree type, int flags)
     dump_type_suffix (pp, type, flags);
 }
 
+struct colorize_guard
+{
+  bool colorize;
+  cxx_pretty_printer *pp;
+
+  colorize_guard (bool _colorize, cxx_pretty_printer *pp, const char *name)
+    : colorize (_colorize && pp_show_color (pp)), pp (pp)
+  {
+    pp_string (pp, colorize_start (colorize, name));
+  }
+  ~colorize_guard ()
+  {
+    pp_string (pp, colorize_stop (colorize));
+  }
+};
+
 /* Print an IDENTIFIER_NODE that is the name of a declaration.  */
 
 static void
@@ -1928,6 +1949,11 @@ dump_exception_spec (cxx_pretty_printer *pp, tree t, int flags)
 static void
 dump_function_name (cxx_pretty_printer *pp, tree t, int flags)
 {
+  bool colorize = flags & (TFF_DECL_SPECIFIERS | TFF_RETURN_TYPE
+			   | TFF_TEMPLATE_HEADER);
+
+  colorize_guard g (colorize, pp, "fnname");
+
   tree name = DECL_NAME (t);
 
   /* We can get here with a decl that was synthesized by language-
@@ -3062,6 +3088,7 @@ reinit_cxx_pp (void)
   cxx_pp->padding = pp_none;
   pp_indentation (cxx_pp) = 0;
   pp_needs_newline (cxx_pp) = false;
+  pp_show_color (cxx_pp) = false;
   cxx_pp->enclosing_scope = current_function_decl;
 }
 
@@ -3208,7 +3235,7 @@ location_of (tree t)
    function.  */
 
 static const char *
-decl_to_string (tree decl, int verbose)
+decl_to_string (tree decl, int verbose, bool show_color)
 {
   int flags = 0;
 
@@ -3222,6 +3249,7 @@ decl_to_string (tree decl, int verbose)
   flags |= TFF_TEMPLATE_HEADER;
 
   reinit_cxx_pp ();
+  pp_show_color (cxx_pp) = show_color;
   dump_decl (cxx_pp, decl, flags);
   return pp_ggc_formatted_text (cxx_pp);
 }
@@ -3321,6 +3349,7 @@ type_to_string (tree typ, int verbose, bool postprocessed, bool *quote,
   flags |= TFF_TEMPLATE_HEADER;
 
   reinit_cxx_pp ();
+  pp_show_color (cxx_pp) = show_color;
 
   if (postprocessed && quote && *quote)
     pp_begin_quote (cxx_pp, show_color);
@@ -3415,7 +3444,7 @@ args_to_string (tree p, int verbose)
    arguments.  */
 
 static const char *
-subst_to_string (tree p)
+subst_to_string (tree p, bool show_color)
 {
   tree decl = TREE_PURPOSE (p);
   tree targs = TREE_VALUE (p);
@@ -3427,6 +3456,7 @@ subst_to_string (tree p)
     return "";
 
   reinit_cxx_pp ();
+  pp_show_color (cxx_pp) = show_color;
   dump_template_decl (cxx_pp, TREE_PURPOSE (p), flags);
   dump_substitution (cxx_pp, NULL, tparms, targs, /*flags=*/0);
   return pp_ggc_formatted_text (cxx_pp);
@@ -3517,7 +3547,7 @@ cp_print_error_function (diagnostic_context *context,
 	    fndecl = current_function_decl;
 
 	  pp_printf (context->printer, function_category (fndecl),
-		     cxx_printable_name_translate (fndecl, 2));
+		     fndecl);
 
 	  while (abstract_origin)
 	    {
@@ -3561,19 +3591,19 @@ cp_print_error_function (diagnostic_context *context,
 		    {
 		      if (context->show_column && s.column != 0)
 			pp_printf (context->printer,
-				   _("    inlined from %qs at %r%s:%d:%d%R"),
-				   cxx_printable_name_translate (fndecl, 2),
+				   _("    inlined from %qD at %r%s:%d:%d%R"),
+				   fndecl,
 				   "locus", s.file, s.line, s.column);
 		      else
 			pp_printf (context->printer,
-				   _("    inlined from %qs at %r%s:%d%R"),
-				   cxx_printable_name_translate (fndecl, 2),
+				   _("    inlined from %qD at %r%s:%d%R"),
+				   fndecl,
 				   "locus", s.file, s.line);
 
 		    }
 		  else
-		    pp_printf (context->printer, _("    inlined from %qs"),
-			       cxx_printable_name_translate (fndecl, 2));
+		    pp_printf (context->printer, _("    inlined from %qD"),
+			       fndecl);
 		}
 	    }
 	  pp_character (context->printer, ':');
@@ -3598,20 +3628,20 @@ function_category (tree fn)
       && DECL_FUNCTION_MEMBER_P (fn))
     {
       if (DECL_STATIC_FUNCTION_P (fn))
-	return _("In static member function %qs");
+	return _("In static member function %qD");
       else if (DECL_COPY_CONSTRUCTOR_P (fn))
-	return _("In copy constructor %qs");
+	return _("In copy constructor %qD");
       else if (DECL_CONSTRUCTOR_P (fn))
-	return _("In constructor %qs");
+	return _("In constructor %qD");
       else if (DECL_DESTRUCTOR_P (fn))
-	return _("In destructor %qs");
+	return _("In destructor %qD");
       else if (LAMBDA_FUNCTION_P (fn))
 	return _("In lambda function");
       else
-	return _("In member function %qs");
+	return _("In member function %qD");
     }
   else
-    return _("In function %qs");
+    return _("In function %qD");
 }
 
 /* Disable warnings about missing quoting in GCC diagnostics for
@@ -4393,7 +4423,7 @@ cp_printer (pretty_printer *pp, text_info *text, const char *spec,
 		break;
 	      }
 	  }
-	result = decl_to_string (temp, verbose);
+	result = decl_to_string (temp, verbose, pp_show_color (pp));
       }
       break;
     case 'E': result = expr_to_string (next_tree);		break;
@@ -4410,7 +4440,7 @@ cp_printer (pretty_printer *pp, text_info *text, const char *spec,
     case 'O': result = op_to_string (false, next_tcode);	break;
     case 'P': result = parm_to_string (next_int);		break;
     case 'Q': result = op_to_string (true, next_tcode);		break;
-    case 'S': result = subst_to_string (next_tree);		break;
+    case 'S': result = subst_to_string (next_tree, pp_show_color (pp)); break;
     case 'T':
       {
 	result = type_to_string (next_tree, verbose, false, quoted,
diff --git a/gcc/diagnostic-color.c b/gcc/diagnostic-color.c
index 1fc5a9079c7..c1406b45d8b 100644
--- a/gcc/diagnostic-color.c
+++ b/gcc/diagnostic-color.c
@@ -91,6 +91,8 @@ static struct color_cap color_dict[] =
   { "locus", SGR_SEQ (COLOR_BOLD), 5, false },
   { "quote", SGR_SEQ (COLOR_BOLD), 5, false },
   { "path", SGR_SEQ (COLOR_BOLD COLOR_SEPARATOR COLOR_FG_CYAN), 4, false },
+  { "fnname", SGR_SEQ (COLOR_BOLD COLOR_SEPARATOR COLOR_FG_GREEN), 6, false },
+  { "targs", SGR_SEQ (COLOR_FG_MAGENTA), 5, false },
   { "fixit-insert", SGR_SEQ (COLOR_FG_GREEN), 12, false },
   { "fixit-delete", SGR_SEQ (COLOR_FG_RED), 12, false },
   { "diff-filename", SGR_SEQ (COLOR_BOLD), 13, false },
-- 
2.27.0

