[RFC PATCH] avoid printing type suffix with %E

[Martin Sebor <msebor at gmail dot com>]

When formatting an integer constant using the %E directive GCC
includes a suffix that indicates its type.  This can perhaps be
useful in some situations but in my experience it's distracting
and gets in the way when writing tests.

Here's an example:

  $ cat b.c && gcc b.c
  constexpr __SIZE_TYPE__ x = 2;

  enum E: bool { e = x };
  b.c:3:20: error: enumerator value 2ul is outside the range of 
underlying type ‘bool’
   enum E: bool { e = x };
                      ^

Notice the "2ul" in the error message.

As far as I can tell, Clang avoids printing the suffix and I think
it would be nice if the GCC pretty printer made it possible to avoid
it as well.

The attached patch implements one such approach by having the pretty
printer recognize the space format flag to suppress the type suffix,
so "%E" still prints the suffix but "% E" does not.  I did this to
preserve the existing output but I think it would be nicer to avoid
printing the suffix with %E and treat (for instance) the pound sign
as a request to add the suffix.  I have tested the attached patch
but not the alternative.

Does anyone have any comments/suggestions for which of the two
approaches would be preferable (or what I may have missed here)?
I CC David as the diagnostic maintainer.

Thanks
Martin

gcc/c/ChangeLog:
2016-10-26  Martin Sebor  <msebor@redhat.com>

	* c-objc-common.c (c_tree_printer::get_flag): Declare new function
	(c_tree_printer::set_flag): Same.

gcc/c-family/ChangeLog:
2016-10-26  Martin Sebor  <msebor@redhat.com>

	* c-pretty-print.c (c_tree_printer::get_flag): Define.
	(c_tree_printer::set_flag): Define.
	(pp_c_integer_constant): Don't print type suffix when space
	is set in flags.
	* c-pretty-print.h (pp_c_flag_space): Add enumerator.

gcc/cp/ChangeLog:
2016-10-26  Martin Sebor  <msebor@redhat.com>

	* error.c (cp_printer): Set space in flags.

gcc/ChangeLog:
2016-10-26  Martin Sebor  <msebor@redhat.com>

	* pretty-print.c (pp_format): Recognize space.
	* pretty-print.h (pretty_printer::get_flag): New function.
	 (pretty_printer::set_flag): Same.

diff --git a/gcc/c-family/c-pretty-print.c b/gcc/c-family/c-pretty-print.c
index 90428ca..7d9375d 100644
--- a/gcc/c-family/c-pretty-print.c
+++ b/gcc/c-family/c-pretty-print.c
@@ -292,6 +292,26 @@ pp_c_pointer (c_pretty_printer *pp, tree t)
     }
 }
 
+bool
+c_pretty_printer::get_flag (char flag)
+{
+  return ' ' == flag && (flags & pp_c_flag_space);
+}
+
+bool
+c_pretty_printer::set_flag (char flag, bool value)
+{
+  gcc_assert (flag == ' ');
+
+  bool previous = c_pretty_printer::get_flag (flag);
+  if (value)
+    flag |= pp_c_flag_space;
+  else
+    flag &= ~pp_c_flag_space;
+
+  return previous;
+}
+
 /* simple-type-specifier:
      type-specifier
 
@@ -926,24 +946,34 @@ pp_c_integer_constant (c_pretty_printer *pp, tree i)
       print_hex (wi, pp_buffer (pp)->digit_buffer);
       pp_string (pp, pp_buffer (pp)->digit_buffer);
     }
-  if (TYPE_UNSIGNED (type))
-    pp_character (pp, 'u');
-  if (type == long_integer_type_node || type == long_unsigned_type_node)
-    pp_character (pp, 'l');
-  else if (type == long_long_integer_type_node
-	   || type == long_long_unsigned_type_node)
-    pp_string (pp, "ll");
-  else for (idx = 0; idx < NUM_INT_N_ENTS; idx ++)
-    if (int_n_enabled_p[idx])
-      {
-	char buf[2+20];
-	if (type == int_n_trees[idx].signed_type
-	    || type == int_n_trees[idx].unsigned_type)
-	  {
-	    sprintf (buf, "I%d", int_n_data[idx].bitsize);
-	    pp_string (pp, buf);
-	  }
-      }
+
+  if (pp->get_flag (' '))
+    {
+      if (TYPE_UNSIGNED (type))
+	pp_character (pp, 'u');
+
+      if (type == long_integer_type_node || type == long_unsigned_type_node)
+	pp_character (pp, 'l');
+      else if (type == long_long_integer_type_node
+	       || type == long_long_unsigned_type_node)
+	pp_string (pp, "ll");
+      else
+	{
+	  for (idx = 0; idx < NUM_INT_N_ENTS; idx ++)
+	    {
+	      if (int_n_enabled_p[idx])
+		{
+		  char buf[2+20];
+		  if (type == int_n_trees[idx].signed_type
+		      || type == int_n_trees[idx].unsigned_type)
+		    {
+		      sprintf (buf, "I%d", int_n_data[idx].bitsize);
+		      pp_string (pp, buf);
+		    }
+		}
+	    }
+	}
+    }
 }
 
 /* Print out a CHARACTER literal.  */
diff --git a/gcc/c-family/c-pretty-print.h b/gcc/c-family/c-pretty-print.h
index 253f192..10ad5d9 100644
--- a/gcc/c-family/c-pretty-print.h
+++ b/gcc/c-family/c-pretty-print.h
@@ -30,7 +30,8 @@ enum pp_c_pretty_print_flags
   {
      pp_c_flag_abstract = 1 << 1,
      pp_c_flag_gnu_v3 = 1 << 2,
-     pp_c_flag_last_bit = 3
+     pp_c_flag_space = 1 << 3,
+     pp_c_flag_last_bit = 4
   };
 
 
@@ -51,6 +52,10 @@ struct c_pretty_printer : pretty_printer
 {
   c_pretty_printer ();
 
+  /* Get and set the format flag.  */
+  virtual bool get_flag (char);
+  virtual bool set_flag (char, bool);
+
   // Format string, possibly translated.
   void translate_string (const char *);
 
diff --git a/gcc/c/c-objc-common.c b/gcc/c/c-objc-common.c
index 20dc024..1bd60cf 100644
--- a/gcc/c/c-objc-common.c
+++ b/gcc/c/c-objc-common.c
@@ -99,6 +99,12 @@ c_tree_printer (pretty_printer *pp, text_info *text, const char *spec,
 	text->set_location (0, DECL_SOURCE_LOCATION (t), true);
     }
 
+  if (' ' == *spec)
+    {
+      pp->set_flag (' ', true);
+      ++spec;
+    }
+
   switch (*spec)
     {
     case 'D':
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 20b20b4..d24ae26 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -3539,6 +3539,12 @@ cp_printer (pretty_printer *pp, text_info *text, const char *spec,
   if (precision != 0 || wide)
     return false;
 
+  if (*spec == ' ')
+    {
+      pp->set_flag (' ');
+      ++spec;
+    }
+
   switch (*spec)
     {
     case 'A': result = args_to_string (next_tree, verbose);	break;
diff --git a/gcc/pretty-print.c b/gcc/pretty-print.c
index a39815e..93b7419 100644
--- a/gcc/pretty-print.c
+++ b/gcc/pretty-print.c
@@ -293,6 +293,11 @@ pp_indent (pretty_printer *pp)
    %.*s: a substring the length of which is specified by an argument
 	 integer.
    %Ns: likewise, but length specified as constant in the format string.
+
+   Flag 'w': wide integer (HOST_WIDE_INT).
+   Flag '+': always print a sign for integer and real constants.
+   Flag ' ': printer-specific.
+   Flag '#': printer-specific.
    Flag 'q': quote formatted text (must come immediately after '%').
 
    Arguments can be used sequentially, or through %N$ resp. *N$
@@ -425,12 +430,14 @@ pp_format (pretty_printer *pp, text_info *text)
       gcc_assert (argno < PP_NL_ARGMAX);
       gcc_assert (!formatters[argno]);
       formatters[argno] = &args[chunk];
+
+      /* Add known format flags.  */
       do
 	{
 	  obstack_1grow (&buffer->chunk_obstack, *p);
 	  p++;
 	}
-      while (strchr ("qwl+#", p[-1]));
+      while (strchr ("qwl+# ", p[-1]));
 
       if (p[-1] == '.')
 	{
diff --git a/gcc/pretty-print.h b/gcc/pretty-print.h
index f49f35a..9d4386f 100644
--- a/gcc/pretty-print.h
+++ b/gcc/pretty-print.h
@@ -213,6 +213,13 @@ struct pretty_printer
 
   virtual ~pretty_printer ();
 
+  /* Get and set the format flag.  */
+  virtual bool get_flag (char) { return false; }
+  virtual bool set_flag (char, bool) { return false; }
+
+  /* Not virtual.  Provided for convenience.  */
+  bool set_flag (char flag) { return set_flag (flag, true); }
+
   /* Where we print external representation of ENTITY.  */
   output_buffer *buffer;