On Tue, Jan 21, 2014 at 11:54:03PM +0100, Marek Polacek wrote:
> On Tue, Jan 21, 2014 at 11:34:42PM +0100, Jakub Jelinek wrote:
> > On Tue, Jan 21, 2014 at 11:30:58PM +0100, Marek Polacek wrote:
> > > I made another small change: in the second hunk, in
> > > emit_side_effect_warnings, I got rid of the while, since it seems to
> > > me we never get COMPOUND_EXPR in TREE_OPERAND (r, 1).
> >
> > For bar (), 1, 2, 3, 4, 5, 6, 7, 8; sure, but what about
> > (1, (2, (3, (4, (5, (6, (bar (), 7))))))); ?
>
> For that `expr' that emit_side_effect_warnings gets is:
> <compound_expr 0x7ffe2724b848
> type <integer_type 0x7ffe27144690 int public SI
> size <integer_cst 0x7ffe271463c0 constant 32>
> unit size <integer_cst 0x7ffe271463e0 constant 4>
> align 32 symtab 0 alias set -1 canonical type 0x7ffe27144690
> precision 32 min <integer_cst 0x7ffe27146360 -2147483648> max <integer_cst
> 0x7ffe27146380 2147483647>
> pointer_to_this <pointer_type 0x7ffe27150738>>
> side-effects
> arg 0 <call_expr 0x7ffe2726a840 type <integer_type 0x7ffe27144690 int>
> side-effects
> fn <addr_expr 0x7ffe2725a720 type <pointer_type 0x7ffe2726e0a8>
> constant arg 0 <function_decl 0x7ffe27250600 bar>
> uu.c:19:32>
> uu.c:19:32>
> arg 1 <integer_cst 0x7ffe2725a760 type <integer_type 0x7ffe27144690 int>
> constant 7>
> uu.c:19:5>
> so we should be fine even in that case.
And for
(bar (), (bar (), (bar (), (bar (), (bar (), (bar (), (bar (), 7)))))));
?
On the other side, there is warn_if_unused_value, which specifically has:
/* Let people do `(foo (), 0)' without a warning. */
if (TREE_CONSTANT (TREE_OPERAND (exp, 1)))
return false;
so perhaps it is intentional that we don't warn about this?
That stuff dates all the way back to r759. Though I wonder why it would
be desirable to warn about this for C++ and not for C.
Jakub
