re PR preprocessor/6521 (-MG creates dependency with wrong path)

	PR preprocessor/6521
	* cppfiles.c (handle_missing_header): Don't do anything
	different for <> includes.
doc:
	* cppopts.texi: Update documentation for -MG.

Co-Authored-By: Neil Booth <neil@daikokuya.demon.co.uk>

From-SVN: r53304

gcc/ChangeLog

+2002-05-08  Robert Spier <rspier@pobox.com>
+	    Neil Booth  <neil@daikokuya.demon.co.uk>
+
+	PR preprocessor/6521
+	* cppfiles.c (handle_missing_header): Don't do anything
+	different for <> includes.
+doc:
+	* cppopts.texi: Update documentation for -MG.
+
 2002-05-08  Neil Booth  <neil@daikokuya.demon.co.uk>
 
 	* cpplex.c (cpp_interpret_charconst): Truncate as well as

gcc/cppfiles.c

@@ -658,30 +658,7 @@ handle_missing_header (pfile, fname, angle_brackets)
   int print_dep = CPP_PRINT_DEPS(pfile) > (angle_brackets || pfile->map->sysp);
 
   if (CPP_OPTION (pfile, print_deps_missing_files) && print_dep)
-    {
-      if (!angle_brackets || IS_ABSOLUTE_PATHNAME (fname))
-	deps_add_dep (pfile->deps, fname);
-      else
-	{
-	  /* If requested as a system header, assume it belongs in
-	     the first system header directory.  */
-	  struct search_path *ptr = CPP_OPTION (pfile, bracket_include);
-	  char *p;
-	  int len = 0, fname_len = strlen (fname);
-
-	  if (ptr)
-	    len = ptr->len;
-
-	  p = (char *) alloca (len + fname_len + 2);
-	  if (len)
-	    {
-	      memcpy (p, ptr->name, len);
-	      p[len++] = '/';
-	    }
-	  memcpy (p + len, fname, fname_len + 1);
-	  deps_add_dep (pfile->deps, p);
-	}
-    }
+    deps_add_dep (pfile->deps, fname);
   /* If -M was specified, then don't count this as an error, because
      we can still produce correct output.  Otherwise, we can't produce
      correct output, because there may be dependencies we need inside

gcc/doc/cppopts.texi

@@ -204,10 +204,13 @@ When used with the driver options @option{-MD} or @option{-MMD},
 
 @item -MG
 @opindex MG
-When used with @option{-M} or @option{-MM}, @option{-MG} says to treat missing
-header files as generated files and assume they live in the same
-directory as the source file.  It suppresses preprocessed output, as a
-missing header file is ordinarily an error.
+In conjunction with an option such as @option{-M} requesting
+dependency generation, @option{-MG} assumes missing header files are
+generated files and adds them to the dependency list without raising
+an error.  The dependency filename is taken directly from the
+@code{#include} directive without prepending any path.  @option{-MG}
+also suppresses preprocessed output, as a missing header file renders
+this useless.
 
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