Manuel LÃpez-IbÃÃez - Wunused-value and Wextra interaction (PR7651 Define -Wextra strictly in (original) (raw)

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Wunused-value and Wextra interaction (PR7651 Define -Wextra strictly in terms of other warning flags)

• From: "Manuel LÃpez-IbÃÃez"
• To: gcc-patches
• Date: Fri, 5 Jan 2007 23:36:31 +0000
• Subject: Wunused-value and Wextra interaction (PR7651 Define -Wextra strictly in terms of other warning flags)

:ADDPATCH c++:This patch continues the effort to fix PR7651 [1].

Currently, Wextra warns when an expression-statement or the left-hand side of a comma expression contains no side effects. However, as it is currently implemented, the same warning is enabled by -Wunused-value, which in turn is enabled by -Wall.

The following patch removes the warning from Wextra and expands the description of Wunused-value to mention this particular case. It also unifies the code that handles the warning for C and C++ into a single function in c-common.c.

A noteworthy difference between C and C++ implementations is that C++ front-end does not emit the warning for empty statements (IS_EMPTY_STMT). I have favoured the C implementation that does not check for this (since there are instances in the testsuite of such cases while there is no test checking the behaviour of the C++ front-end). Is there any rationale for not emitting the warning for empty statements in C++?

Bootstrapped and regression tested with --enable-languages=all on i686-pc-linux-gnu.

OK for mainline?[1] http://gcc.gnu.org/ml/gcc-patches/2006-12/msg01103.html2007-01-05 Manuel Lopez-Ibanez manu@gcc.gnu.org

PR middle-end/7651

• doc/invoke.texi (Wunused-value): Update description. (Wextra): Delete item.
• opts.c (set_Wextra): Don't use the value of Wextra to set the value of Wunused-value.
• c-typeck.c (c_process_expr_stmt): Don't check extra_warnings. (c_finish_stmt_expr): Don't check extra_warnings. (emit_side_effect_warnings): Move function to...
• c-common.c (emit_side_effect_warnings): ... here.
• c-common.h (emit_side_effect_warnings): Declare.

cp/ 2007-01-05 Manuel Lopez-Ibanez manu@gcc.gnu.org

PR middle-end/7651

• cp-gimplify.c (gimplify_expr_stmt): Call emit_side_effect_warnings in c-common.c. Don't check extra_warnings.

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