Re: [driver, doc] Support escaping special characters in specs

[Rainer Orth <ro at CeBiTec dot Uni-Bielefeld dot DE>]

Hi Joseph,

> On Fri, 13 Jan 2017, Rainer Orth wrote:
>
>> I'm unsure if the patch is large enough to need a copyright assignment
>> (in which case it's almost certainly too late for GCC 7), and even if
>> not if it's appropriate at this point in the release cycle.
>
> I think it's big enough to need an assignment.

Jeff informed me that he'd received confirmation from the FSF that his
assignment has been processed.

> Note missing spaces before '(' in calls to free, and after ')' in a cast.

Fixed in the following revised patch, which also incorporates Sandra's
review comments.

Bootstrapped without regressions on i386-pc-solaris2.12 and
x86_64-pc-linux-gnu, in a tree which also contained the patch for PR
target/40411 which needs this feature.

The doc parts have been checked separately with

$ make doc/gcc.info doc/gcc.pdf

and visual inspection of the output.

Ok for mainline either now or when GCC 8 stage 1 opens?

Thanks.
	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


2017-01-10  Jeff Downs  <heydowns@somuchpressure.net>
	    Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	* gcc.c (handle_braces): Support escaping in switch matching
	text.
	* doc/invoke.texi (Spec Files): Document it.
	Remove superfluous @code markup in items.

# HG changeset patch
# Parent  12dd51d3fddd52cbb3925fe2a7950cb8df0ad230
Support escaping special characters in specs

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -26207,7 +26207,7 @@ Substitute the variable part of a matche
 Note that each comma in the substituted string is replaced by
 a single space.
 
-@item %<@code{S}
+@item %<S
 Remove all occurrences of @code{-S} from the command line.  Note---this
 command is position dependent.  @samp{%} commands in the spec string
 before this one see @code{-S}, @samp{%} commands in the spec string
@@ -26305,7 +26305,7 @@ It is used to separate compiler options 
 in the @option{--target-help} output.
 @end table
 
-@item %@{@code{S}@}
+@item %@{S@}
 Substitutes the @code{-S} switch, if that switch is given to GCC@.
 If that switch is not specified, this substitutes nothing.  Note that
 the leading dash is omitted when specifying this option, and it is
@@ -26313,11 +26313,11 @@ automatically inserted if the substituti
 string @samp{%@{foo@}} matches the command-line option @option{-foo}
 and outputs the command-line option @option{-foo}.
 
-@item %W@{@code{S}@}
+@item %W@{S@}
 Like %@{@code{S}@} but mark last argument supplied within as a file to be
 deleted on failure.
 
-@item %@{@code{S}*@}
+@item %@{S*@}
 Substitutes all the switches specified to GCC whose names start
 with @code{-S}, but which also take an argument.  This is used for
 switches like @option{-o}, @option{-D}, @option{-I}, etc.
@@ -26325,19 +26325,19 @@ GCC considers @option{-o foo} as being
 one switch whose name starts with @samp{o}.  %@{o*@} substitutes this
 text, including the space.  Thus two arguments are generated.
 
-@item %@{@code{S}*&@code{T}*@}
+@item %@{S*&T*@}
 Like %@{@code{S}*@}, but preserve order of @code{S} and @code{T} options
 (the order of @code{S} and @code{T} in the spec is not significant).
 There can be any number of ampersand-separated variables; for each the
 wild card is optional.  Useful for CPP as @samp{%@{D*&U*&A*@}}.
 
-@item %@{@code{S}:@code{X}@}
+@item %@{S:X@}
 Substitutes @code{X}, if the @option{-S} switch is given to GCC@.
 
-@item %@{!@code{S}:@code{X}@}
+@item %@{!S:X@}
 Substitutes @code{X}, if the @option{-S} switch is @emph{not} given to GCC@.
 
-@item %@{@code{S}*:@code{X}@}
+@item %@{S*:X@}
 Substitutes @code{X} if one or more switches whose names start with
 @code{-S} are specified to GCC@.  Normally @code{X} is substituted only
 once, no matter how many such switches appeared.  However, if @code{%*}
@@ -26362,19 +26362,19 @@ when matching an option like @option{-mc
 --script=newchip/memory.ld
 @end smallexample
 
-@item %@{.@code{S}:@code{X}@}
+@item %@{.S:X@}
 Substitutes @code{X}, if processing a file with suffix @code{S}.
 
-@item %@{!.@code{S}:@code{X}@}
+@item %@{!.S:X@}
 Substitutes @code{X}, if @emph{not} processing a file with suffix @code{S}.
 
-@item %@{,@code{S}:@code{X}@}
+@item %@{,S:X@}
 Substitutes @code{X}, if processing a file for language @code{S}.
 
-@item %@{!,@code{S}:@code{X}@}
+@item %@{!,S:X@}
 Substitutes @code{X}, if not processing a file for language @code{S}.
 
-@item %@{@code{S}|@code{P}:@code{X}@}
+@item %@{S|P:X@}
 Substitutes @code{X} if either @code{-S} or @code{-P} is given to
 GCC@.  This may be combined with @samp{!}, @samp{.}, @samp{,}, and
 @code{*} sequences as well, although they have a stronger binding than
@@ -26409,7 +26409,14 @@ be as many clauses as you need.  This ma
 
 @end table
 
-The conditional text @code{X} in a %@{@code{S}:@code{X}@} or similar
+The switch matching text @code{S} in a @samp{%@{S@}}, @samp{%@{S:X@}}
+or similar construct can use a backslash to ignore the special meaning
+of the character following it, thus allowing literal matching of a
+character that is otherwise specially treated.  For example,
+@samp{%@{std=iso9899\:1999:X@}} substitutes @code{X} if the
+@option{-std=iso9899:1999} option is given.
+
+The conditional text @code{X} in a @samp{%@{S:X@}} or similar
 construct may contain other nested @samp{%} constructs or spaces, or
 even newlines.  They are processed as usual, as described above.
 Trailing white space in @code{X} is ignored.  White space may also
diff --git a/gcc/gcc.c b/gcc/gcc.c
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -584,6 +584,12 @@ or with constant text in a single argume
 
  %(Spec) processes a specification defined in a specs file as *Spec:
 
+The switch matching text S in a %{S}, %{S:X}, or similar construct can use
+a backslash to ignore the special meaning of the character following it,
+thus allowing literal matching of a character that is otherwise specially
+treated.  For example, %{std=iso9899\:1999:X} substitutes X if the
+-std=iso9899:1999 option is given.
+
 The conditional text X in a %{S:X} or similar construct may contain
 other nested % constructs or spaces, or even newlines.  They are
 processed as usual, as described above.  Trailing white space in X is
@@ -6237,6 +6243,8 @@ handle_braces (const char *p)
 {
   const char *atom, *end_atom;
   const char *d_atom = NULL, *d_end_atom = NULL;
+  char *esc_buf = NULL, *d_esc_buf = NULL;
+  int esc;
   const char *orig = p;
 
   bool a_is_suffix;
@@ -6287,11 +6295,42 @@ handle_braces (const char *p)
 	    p++, a_is_spectype = true;
 
 	  atom = p;
+	  esc = 0;
 	  while (ISIDNUM (*p) || *p == '-' || *p == '+' || *p == '='
-		 || *p == ',' || *p == '.' || *p == '@')
-	    p++;
+		 || *p == ',' || *p == '.' || *p == '@' || *p == '\\')
+	    {
+	      if (*p == '\\')
+		{
+		  p++;
+		  if (!*p)
+		    fatal_error (input_location,
+				 "braced spec %qs ends in escape", orig);
+		  esc++;
+		}
+	      p++;
+	    }
 	  end_atom = p;
 
+	  if (esc)
+	    {
+	      const char *ap;
+	      char *ep;
+
+	      if (esc_buf && esc_buf != d_esc_buf)
+		free (esc_buf);
+	      esc_buf = NULL;
+	      ep = esc_buf = (char *) xmalloc (end_atom - atom - esc + 1);
+	      for (ap = atom; ap != end_atom; ap++, ep++)
+		{
+		  if (*ap == '\\')
+		    ap++;
+		  *ep = *ap;
+		}
+	      *ep = '\0';
+	      atom = esc_buf;
+	      end_atom = ep;
+	    }
+
 	  if (*p == '*')
 	    p++, a_is_starred = 1;
 	}
@@ -6358,6 +6397,7 @@ handle_braces (const char *p)
 		      disj_matched = true;
 		      d_atom = atom;
 		      d_end_atom = end_atom;
+		      d_esc_buf = esc_buf;
 		    }
 		}
 	    }
@@ -6369,7 +6409,7 @@ handle_braces (const char *p)
 	      p = process_brace_body (p + 1, d_atom, d_end_atom, disj_starred,
 				      disj_matched && !n_way_matched);
 	      if (p == 0)
-		return 0;
+		goto done;
 
 	      /* If we have an N-way choice, reset state for the next
 		 disjunction.  */
@@ -6390,6 +6430,12 @@ handle_braces (const char *p)
     }
   while (*p++ != '}');
 
+ done:
+  if (d_esc_buf && d_esc_buf != esc_buf)
+    free (d_esc_buf);
+  if (esc_buf)
+    free (esc_buf);
+
   return p;
 
  invalid: