c++: fix ICE with -Wduplicated-cond [PR107593]
Here we crash because a CAST_EXPR, representing T(), doesn't have
its operand, and operand_equal_p's STRIP_ANY_LOCATION_WRAPPER doesn't
expect that. (o_e_p is called from warn_duplicated_cond_add_or_warn.)
In the past we've adjusted o_e_p to better cope with template codes,
but in this case I think we just want to avoid attempting to warn
about inst-dependent expressions; I don't think I've ever envisioned
-Wduplicated-cond to warn about them. Also destroy the chain when
an inst-dependent expression is encountered to not warn in
Wduplicated-cond4.C.
The ICE started with r12-6022, two-stage name lookup for overloaded
operators, which gave dependent operators a TREE_TYPE (in particular,
DEPENDENT_OPERATOR_TYPE), so we no longer bail out here in o_e_p:
/* Similar, if either does not have a type (like a template id),
they aren't equal. */
if (!TREE_TYPE (arg0) || !TREE_TYPE (arg1))
return false;
PR c++/107593
PR c++/108597
gcc/c-family/ChangeLog:
* c-common.h (instantiation_dependent_expression_p): Declare.
* c-warn.cc (warn_duplicated_cond_add_or_warn): If the condition
is dependent, invalidate the chain.
gcc/c/ChangeLog:
* c-objc-common.cc (instantiation_dependent_expression_p): New.
gcc/cp/ChangeLog:
* cp-tree.h (instantiation_dependent_expression_p): Don't
declare here.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wduplicated-cond3.C: New test.
* g++.dg/warn/Wduplicated-cond4.C: New test.
* g++.dg/warn/Wduplicated-cond5.C: New test.