2010-04-07 Jakub Jelinek <jakub@redhat.com>
+ 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.
+
* tree-ssa-pre.c (my_rev_post_order_compute): Remove set but not
used count variable.
* genemit.c (gen_expand, gen_split): Avoid set but not used warnings