From ebfbbdc556443d1ea95923b596f59411256bd9b5 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Wed, 7 Apr 2010 22:33:36 +0200
Subject: re PR c/18624 (GCC does not detect local variable set but never used)

	PR c/18624
	* tree.h (DECL_READ_P): Define.
	(struct tree_decl_common): Add decl_read_flag.
	* c-decl.c (pop_scope): If TREE_USED but !DECL_READ_P, issue
	a set but not used warning.
	(merge_decls): Merge DECL_READ_P flag.
	(finish_decl, build_compound_literal): Set DECL_READ_P flag.
	(finish_function): Issue -Wunused-but-set-parameter diagnostics.
	* c-common.c (handle_used_attribute, handle_unused_attribute):
	Likewise.
	* c-tree.h (default_function_array_read_conversion, mark_exp_read):
	New prototypes.
	* c-typeck.c (default_function_array_read_conversion, mark_exp_read):
	New functions.
	(default_conversion, c_process_expr_stmt): Call mark_exp_read.
	* c-parser.c (c_parser_initializer, c_parser_expr_no_commas,
	c_parser_binary_expression, c_parser_cast_expression,
	c_parser_expr_list, c_parser_omp_atomic, c_parser_omp_for_loop):
	Call default_function_array_read_conversion instead of
	default_function_array_conversion where needed.
	(c_parser_unary_expression, c_parser_conditional_expression,
	c_parser_postfix_expression_after_primary, c_parser_initelt):
	Likewise.  Call mark_exp_read where needed.
	(c_parser_statement_after_labels, c_parser_asm_operands,
	c_parser_typeof_specifier, c_parser_sizeof_expression,
	c_parser_alignof_expression, c_parser_initval): Call mark_exp_read
	where needed.
	* common.opt (Wunused-but-set-variable, Wunused-but-set-parameter):
	New.
	* toplev.c (warn_unused_but_set_variable): Default to warn_unused.
	(warn_unused_but_set_parameter): Default to warn_unused
	&& extra_warnings.
	* doc/invoke.texi: Document -Wunused-but-set-variable and
	-Wunused-but-set-parameter.

	* objc-act.c (finish_var_decl, objc_begin_catch_clause,
	really_start_method, get_super_receiver, handle_class_ref): Set
	DECL_READ_P in addition to TREE_USED.

	* gcc.dg/Wunused-var-1.c: New test.
	* gcc.dg/Wunused-var-2.c: New test.
	* gcc.dg/Wunused-var-3.c: New test.
	* gcc.dg/Wunused-var-4.c: New test.
	* gcc.dg/Wunused-var-5.c: New test.
	* gcc.dg/Wunused-var-6.c: New test.
	* gcc.dg/Wunused-parm-1.c: New test.

From-SVN: r158086
---
 gcc/toplev.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'gcc/toplev.c')

diff --git a/gcc/toplev.c b/gcc/toplev.c
index 68a1b8c..798f0d4 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1796,6 +1796,12 @@ process_options (void)
     warn_unused_parameter = (warn_unused && extra_warnings);
   if (warn_unused_variable == -1)
     warn_unused_variable = warn_unused;
+  /* Wunused-but-set-parameter is enabled if both -Wunused -Wextra are
+     enabled.  */
+  if (warn_unused_but_set_parameter == -1)
+    warn_unused_but_set_parameter = (warn_unused && extra_warnings);
+  if (warn_unused_but_set_variable == -1)
+    warn_unused_but_set_variable = warn_unused;
   if (warn_unused_value == -1)
     warn_unused_value = warn_unused;
 
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