RFA: Change behaviour of %* in spec strings

[Nick Clifton <nickc at redhat dot com>]

Hi Guys,

  I would like to make a change to the way %* behaves in spec strings.
  Currently whenever %* is encountered the text that was previously
  matched is substituted, followed by a space.  Thus %{foo=*:bar%*baz}
  would match -foo=4 and insert 'bar4 baz'.  I would like to change this
  so that the space is only inserted if %* is at the end of a spec
  sequence.  (In all of the strings currently built in to gcc this is
  the case, so my patch will not change current behaviour).

  The motivation is that I want to construct a pathname based on a
  command line option using a spec string like this:

    %{mmcu=*:--script=%*/memory.ld}

  So that if the user invokes -mmcu=msp430f2617 then gcc will generate:

    --script=msp430f2617/memory.ld

  A spec string like this however:

    %{mmcu=*:--script=%*}/memory.ld

  would match the current behaviour and generate:
  
    --script=msp430f2617 /memory.ld

  As a secondary feature of the patch I have also updated the
  documentation to explicitly state when a space will be inserted into
  the generated text.

  I have tested the patch and found no regressions using an
  i686-pc-liunx-gnu toolchain and an msp430-elf toolchain.

  OK to apply ?

Cheers
  Nick

gcc/ChangeLog
2013-10-17  Nick Clifton  <nickc@redhat.com>

	* gcc.c (do_spec_1): Do not insert a space after a %* substitution
	unless it is the last part of a spec substring.
        * doc/invoke.texi (Spec Files): Document space insertion
	behaviour of %*.

Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 203750)
+++ gcc/doc/invoke.texi	(working copy)
@@ -10929,6 +10929,22 @@
 for each matching switch, with the @code{%*} replaced by the part of
 that switch matching the @code{*}.
 
+If @code{%*} appears as the last part of a spec sequence then a space
+will added after the end of the last substitution.  If there is more
+text in the sequence however then a space will not be generated.  This
+allows the @code{%*} substitution to be used as part of a larger
+string.  For example, a spec string like this:
+
+@smallexample
+%@{mcu=*:--script=%*/memory.ld@}
+@end smallexample
+
+when matching an option like @code{-mcu=newchip} will produce:
+
+@smallexample
+--script=newchip/memory.ld
+@end smallexample
+
 @item %@{.@code{S}:@code{X}@}
 Substitutes @code{X}, if processing a file with suffix @code{S}.
 
Index: gcc/gcc.c
===================================================================
--- gcc/gcc.c	(revision 203750)
+++ gcc/gcc.c	(working copy)
@@ -388,7 +388,8 @@
  %2	process CC1PLUS_SPEC as a spec.
  %*	substitute the variable part of a matched option.  (See below.)
 	Note that each comma in the substituted string is replaced by
-	a single space.
+	a single space.  A space is appended after the last substitution
+	unless there is more text in current sequence.
  %<S    remove all occurrences of -S from the command line.
         Note - this command is position dependent.  % commands in the
         spec string before this one will see -S, % commands in the
@@ -422,7 +423,9 @@
           once, no matter how many such switches appeared.  However,
           if %* appears somewhere in X, then X will be substituted
           once for each matching switch, with the %* replaced by the
-          part of that switch that matched the '*'.
+          part of that switch that matched the '*'.  A space will be
+	  appended after the last substitution unless there is more
+	  text in current sequence.
  %{.S:X}  substitutes X, if processing a file with suffix S.
  %{!.S:X} substitutes X, if NOT processing a file with suffix S.
  %{,S:X}  substitutes X, if processing a file which will use spec S.
@@ -5375,7 +5378,17 @@
 	      {
 		if (soft_matched_part[0])
 		  do_spec_1 (soft_matched_part, 1, NULL);
-		do_spec_1 (" ", 0, NULL);
+		/* Only insert a space after the substitution if it is at the
+		   end of the current sequence.  So if:
+
+		     "%{foo=*:bar%*}%{foo=*:one%*two}"
+
+		   matches -foo=hello then it will produce:
+		   
+		     barhello onehellotwo
+		*/
+		if (*p == 0 || *p == '}')
+		  do_spec_1 (" ", 0, NULL);
 	      }
 	    else
 	      /* Catch the case where a spec string contains something like