* Makefile.in (WARN_CFLAGS): Add -Wwrite-strings.
(tree.o): Depend on output.h.
* c-decl.c (pending_invalid_xref_file,
current_function_prototype_file): Constify.
(pushdecl): Constify a local char *.
(define_label): Constify filename parameter.
* c-lex.c (init_parse): Constify parameter and return value.
* c-typeck.c (c_expand_asm_operands): Constify filename parameter.
* c-tree.h: Update prototypes.
* c-parse.in: Constify filename member of %union, and if_stmt_file.
* c-parse.y, c-parse.c, c-parse.h, objc/objc-parse.y,
objc/objc-parse.c: Regenerate.
* dwarfout.c (dwarfout_init): Constify main_input_filename parameter.
* dwarfout.h: Update prototypes.
* expr.c (expand_expr): Constify a local char *.
* flags.h: Constify main_input_filename.
* function.c (expand_function_end): Constify filename parameter.
* genrecog.c (make_insn_sequence): Use a character array for
c_test_pos.
(main): Remove unused variables.
* input.h: Constify input_filename, main_input_filename, and
file_stack.name. Update prototypes.
* output.h: Declare first_global_object_name and
weak_global_object_name here, as const char *.
* stmt.c (expand_asm_operands): Constify filename parameter.
* toplev.c (compile_file, push_srcloc, debug_start_source_file):
Constify filename parameter.
(input_filename, main_input_filename): Constify.
* toplev.h: Update prototypes.
* tree.c: Include output.h. Don't declare
first_global_object_name or weak_global_object_name. Clean up string
bashing in get_file_function_name_long.
* tree.h (struct tree_decl): Constify filename member.
(input_filename): Constify.
Update prototypes.
* varasm.c (first_global_object_name, weak_global_object_name):
Constify.
(assemble_start_function, assemble_variable): Clean up string bashing.
* gcc.c: Constify all spec-related strings initialized,
transitively, from string constants. Constify all strings
and string variables related to multilibs.
(set_spec, read_specs): Cast argument to free to PTR.
(used_arg): Do not modify multilib_matches. Use strncmp plus
length comparison to compare multilib switches.
* genmultilib: Constify everything declared in multilib.h.