c-pch.c: Include flags.h.

	* c-pch.c: Include flags.h.  Add comments to routines.
	(struct c_pch_validity): New.
	(get_ident): Update PCH file version number.
	(pch_init): Output current debugging type.
	(c_common_valid_pch): Check debugging type.
	* Makefile.in (c-pch.o): Update dependencies.
	* flags.h (debug_type_names): Declare.
	* toplev.c (debug_type_names): Move out of decode_g_option.

From-SVN: r65499

gcc/ChangeLog

@@ -2,6 +2,15 @@
 
 	* doc/extend.texi (Empty Structures): New.
 
+	* c-pch.c: Include flags.h.  Add comments to routines.
+	(struct c_pch_validity): New.
+	(get_ident): Update PCH file version number.
+	(pch_init): Output current debugging type.
+	(c_common_valid_pch): Check debugging type.
+	* Makefile.in (c-pch.o): Update dependencies.
+	* flags.h (debug_type_names): Declare.
+	* toplev.c (debug_type_names): Move out of decode_g_option.
+
 2003-04-11  Eric Christopher  <echristo@redhat.com>
 
 	* emit-rtl.c (gen_rtx): Fix typos.

gcc/Makefile.in

@@ -1336,7 +1336,8 @@ c-dump.o : c-dump.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \
 	$(C_TREE_H) tree-dump.h
 
 c-pch.o : c-pch.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(CPPLIB_H) $(TREE_H) \
-	c-common.h output.h toplev.h c-pragma.h $(GGC_H) debug.h langhooks.h
+	c-common.h output.h toplev.h c-pragma.h $(GGC_H) debug.h langhooks.h \
+	flags.h
 
 # Language-independent files.
 

gcc/c-pch.c

@@ -23,6 +23,7 @@ Boston, MA 02111-1307, USA.  */
 #include "coretypes.h"
 #include "cpplib.h"
 #include "tree.h"
+#include "flags.h"
 #include "c-common.h"
 #include "output.h"
 #include "toplev.h"
@@ -31,6 +32,11 @@ Boston, MA 02111-1307, USA.  */
 #include "ggc.h"
 #include "langhooks.h"
 
+struct c_pch_validity
+{
+  unsigned char debug_info_type;
+};
+
 struct c_pch_header 
 {
   unsigned long asm_size;
@@ -45,11 +51,16 @@ static long asm_file_startpos;
 
 static const char * get_ident PARAMS((void));
 
+/* Compute an appropriate 8-byte magic number for the PCH file, so that
+   utilities like file(1) can identify it, and so that GCC can quickly
+   ignore non-PCH files and PCH files that are of a completely different
+   format.  */
+
 static const char *
 get_ident()
 {
   static char result[IDENT_LENGTH];
-  static const char template[IDENT_LENGTH] = "gpch.010";
+  static const char template[IDENT_LENGTH] = "gpch.011";
   
   memcpy (result, template, IDENT_LENGTH);
   if (c_language == clk_c)
@@ -61,19 +72,26 @@ get_ident()
   return result;
 }
 
+/* Prepare to write a PCH file.  This is called at the start of 
+   compilation.  */
+
 void
 pch_init ()
 {
   FILE *f;
+  struct c_pch_validity v;
+  
+  if (! pch_file)
+    return;
   
-  if (pch_file)
-    {
   f = fopen (pch_file, "w+b");
   if (f == NULL)
     fatal_io_error ("can't open %s", pch_file);
   pch_outfile = f;
   
-      if (fwrite (get_ident(), IDENT_LENGTH, 1, f) != 1)
+  v.debug_info_type = write_symbols;
+  if (fwrite (get_ident(), IDENT_LENGTH, 1, f) != 1
+      || fwrite (&v, sizeof (v), 1, f) != 1)
     fatal_io_error ("can't write to %s", pch_file);
 
   /* We need to be able to re-read the output.  */
@@ -88,9 +106,11 @@ pch_init ()
   (*debug_hooks->handle_pch) (0);
   
   cpp_save_state (parse_in, f);
-    }
 }
 
+/* Write the PCH file.  This is called at the end of a compilation which
+   will produce a PCH file.  */
+
 void
 c_common_write_pch ()
 {
@@ -134,6 +154,9 @@ c_common_write_pch ()
   fclose (pch_outfile);
 }
 
+/* Check the PCH file called NAME, open on FD, to see if it can be used
+   in this compilation.  */
+
 int
 c_common_valid_pch (pfile, name, fd)
      cpp_reader *pfile;
@@ -144,12 +167,13 @@ c_common_valid_pch (pfile, name, fd)
   int result;
   char ident[IDENT_LENGTH];
   const char *pch_ident;
+  struct c_pch_validity v;
 
   if (! allow_pch)
     return 2;
 
   /* Perform a quick test of whether this is a valid
-     precompiled header for C.  */
+     precompiled header for the current language.  */
 
   sizeread = read (fd, ident, IDENT_LENGTH);
   if (sizeread == -1)
@@ -181,6 +205,26 @@ c_common_valid_pch (pfile, name, fd)
       return 2;
     }
 
+  if (read (fd, &v, sizeof (v)) != sizeof (v))
+    {
+      fatal_io_error ("can't read %s", name);
+      return 2;
+    }
+
+  /* The allowable debug info combinations are that either the PCH file
+     was built with the same as is being used now, or the PCH file was
+     built for some kind of debug info but now none is in use.  */
+  if (v.debug_info_type != write_symbols
+      && write_symbols != NO_DEBUG)
+    {
+      if (cpp_get_options (pfile)->warn_invalid_pch)
+	cpp_error (pfile, DL_WARNING, 
+		   "%s: created with -g%s, but used with -g%s", name,
+		   debug_type_names[v.debug_info_type],
+		   debug_type_names[write_symbols]);
+      return 2;
+    }
+
   /* Check the preprocessor macros are the same as when the PCH was
      generated.  */
   
@@ -191,6 +235,9 @@ c_common_valid_pch (pfile, name, fd)
     return result == 0;
 }
 
+/* Load in the PCH file NAME, open on FD.  It was originally searched for
+   by ORIG_NAME.  */
+
 void
 c_common_read_pch (pfile, name, fd, orig_name)
      cpp_reader *pfile;

gcc/flags.h

@@ -41,6 +41,9 @@ enum debug_info_type
 /* Specify which kind of debugging info to generate.  */
 extern enum debug_info_type write_symbols;
 
+/* Names of debug_info_type, for error messages.  */
+extern const char *const debug_type_names[];
+
 enum debug_info_level
 {
   DINFO_LEVEL_NONE,	/* Write no debugging info.  */

gcc/toplev.c

@@ -4268,6 +4268,12 @@ decode_W_option (arg)
   return 1;
 }
 
+/* Indexed by enum debug_info_type.  */
+const char *const debug_type_names[] =
+{
+  "none", "stabs", "coff", "dwarf-1", "dwarf-2", "xcoff", "vms"
+};
+
 /* Parse a -g... command line switch.  ARG is the value after the -g.
    It is safe to access 'ARG - 2' to generate the full switch name.
    Return the number of strings consumed.  */
@@ -4287,11 +4293,6 @@ decode_g_option (arg)
      -g and -ggdb don't explicitly set the debugging format so
      -gdwarf -g3 is equivalent to -gdwarf3.  */
   static int type_explicitly_set_p = 0;
-  /* Indexed by enum debug_info_type.  */
-  static const char *const debug_type_names[] =
-  {
-    "none", "stabs", "coff", "dwarf-1", "dwarf-2", "xcoff", "vms"
-  };
 
   /* The maximum admissible debug level value.  */
   static const unsigned max_debug_level = 3;