[4.5] PR32061 PR36954 Wlogical-op fixes

[Manuel López-Ibáñez <lopezibanez at gmail dot com>]

The following patch makes Wlogical-op warn less (in particular, not
warn for op && 1 or op && 0), it fixes two bugs and it also enables it
with Wextra. It also changes the wording of the warning from:

logical '&&' with non-zero constant will always evaluate as true
logical '||' with non-zero constant will always evaluate as true

to:

logical 'and' applied to non-boolean constant
logical 'or' applied to non-boolean constant

Bootstrapped and regression tested on x86_64-unknown-linux-gnu.

OK for 4.5?


2009-02-18  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c/32061
	PR c++/36954
	* doc/invoke.texi: Add -Wlogical-op to -Wextra.
	* common.opt (Wlogical-op): Move from here...
	* c.opt (Wlogical-op): ... to here.
	* c-typeck.c (parser_build_binary_op): Update call to
	warn_logical_operator.
	* c-opts.c (c_common_post_options): Enable warn_logical_op with
	extra_warnings.
	* c-common.c (warn_logical_op): Update.
	* c-common.h (warn_logical_op): Update declaration.
cp/
	* call.c (build_new_op): Save the original codes of operands
	before folding.
	
testsuite/
	* gcc.dg/pr32061.c: New.
	* gcc.dg/Wlogical-op-1.c: Update.
	* g++.dg/warn/Wlogical-op-1.C: Update.
	* g++.dg/warn/pr36954.C: New.

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