Fix PR preprocessor/7358 re SUNPRO_DEPENDENCIES

Fix PR preprocessor/7358 re SUNPRO_DEPENDENCIES

[Neil Booth]

SUNPRO_DEPENDENCIES is a little odd, in that it is not supposed
to output the dependence on the main file.  [This is the way
it works in Sun's compiler from which we copied the environment
variable.]

It seems this subtlety was lost during the breakout of mkdeps.c
about 2.5 years ago.  I'm not sure whether DEPENDENCIES_OUTPUT
is a gcc-native environment variable (anyone?).  It's behaviour
has tracked SUNPRO_DEPENDENCIES because they share code.

If it is GCC-specific, I'm inclined to leave it with the new
behaviour of including the dependence on the main file.
But I'm reverting the behaviour of S_D to be compatible with
Sun's compiler.  Apparently this behaviour is useful when
temporary files are involved.

Neil.

	* c-opts.c (check_deps_environment_vars): Ignore main file
	for SUNPRO_DEPENDENCIES.
	* cppfiles.c (stack_include_file): Ignore main file if
	appropriate.
	* cpplib.h (struct cpp_options): New member in deps.
	* doc/cppenv.texi: Update.

Index: c-opts.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/c-opts.c,v
retrieving revision 1.13
diff -u -p -r1.13 c-opts.c
--- c-opts.c	14 Aug 2002 17:19:28 -0000	1.13
+++ c-opts.c	14 Aug 2002 21:48:14 -0000
@@ -1467,7 +1467,8 @@ c_common_finish ()
    DEPS_TARGET", where OUTPUT_FILE is the file to write deps info to
    and DEPS_TARGET is the target to mention in the deps.  They also
    result in dependency information being appended to the output file
-   rather than overwriting it.  */
+   rather than overwriting it, and like Sun's compiler
+   SUNPRO_DEPENDENCIES suppresses the dependency on the main file.  */
 static void
 check_deps_environment_vars ()
 {
@@ -1480,7 +1481,10 @@ check_deps_environment_vars ()
     {
       GET_ENVIRONMENT (spec, "SUNPRO_DEPENDENCIES");
       if (spec)
-	cpp_opts->deps.style = DEPS_SYSTEM;
+	{
+	  cpp_opts->deps.style = DEPS_SYSTEM;
+	  cpp_opts->deps.ignore_main_file = true;
+	}
     }
 
   if (spec)
Index: cppfiles.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cppfiles.c,v
retrieving revision 1.153
diff -u -p -r1.153 cppfiles.c
--- cppfiles.c	12 Aug 2002 22:44:29 -0000	1.153
+++ cppfiles.c	14 Aug 2002 21:48:14 -0000
@@ -318,9 +318,12 @@ stack_include_file (pfile, inc)
   sysp = MAX ((pfile->map ? pfile->map->sysp : 0),
 	      (inc->foundhere ? inc->foundhere->sysp : 0));
 
-  /* For -M, add the file to the dependencies on its first inclusion.  */
+  /* Add the file to the dependencies on its first inclusion.  */
   if (CPP_OPTION (pfile, deps.style) > !!sysp && !inc->include_count)
-    deps_add_dep (pfile->deps, inc->name);
+    {
+      if (pfile->buffer || CPP_OPTION (pfile, deps.ignore_main_file) == 0)
+	deps_add_dep (pfile->deps, inc->name);
+    }
 
   /* Not in cache?  */
   if (! inc->buffer)
Index: cpplib.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cpplib.h,v
retrieving revision 1.233
diff -u -p -r1.233 cpplib.h
--- cpplib.h	12 Aug 2002 22:44:30 -0000	1.233
+++ cpplib.h	14 Aug 2002 21:48:15 -0000
@@ -387,6 +387,9 @@ struct cpp_options
     /* Generate phony targets for each dependency apart from the first
        one.  */
     bool phony_targets;
+
+    /* If true, no dependency is generated on the main file.  */
+    bool ignore_main_file;
   } deps;
 
   /* Target-specific features set by the front end or client.  */
Index: doc/cppenv.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/cppenv.texi,v
retrieving revision 1.3
diff -u -p -r1.3 cppenv.texi
--- doc/cppenv.texi	26 Mar 2002 03:25:05 -0000	1.3
+++ doc/cppenv.texi	14 Aug 2002 21:48:15 -0000
@@ -72,7 +72,8 @@ with an optional @option{-MT} switch too
 @cindex dependencies for make as output
 This variable is the same as @env{DEPENDENCIES_OUTPUT} (see above),
 except that system header files are not ignored, so it implies
-@option{-M} rather than @option{-MM}.
+@option{-M} rather than @option{-MM}.  However, the dependence on the
+main input file is omitted.
 @ifset cppmanual
 @xref{Invocation}.
 @end ifset