On Thu, 26 Oct 2023, Jason Merrill wrote:
On 10/25/23 14:55, Patrick Palka wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
OK for trunk?
-- >8 --
Now that we don't have to worry about looking thruogh NON_DEPENDENT_EXPR,
we can easily extend the -Wparentheses warning in convert_for_assignment
to consider (non-dependent) templated assignment operator expressions as
well, like r14-4111-g6e92a6a2a72d3b did in maybe_convert_cond.
gcc/cp/ChangeLog:
* cp-tree.h (is_assignment_op_expr_p): Declare.
* semantics.cc (is_assignment_op_expr_p): Generalize to return
true for assignment operator expression, not just one that
have been resolved to an operator overload.
(maybe_convert_cond): Remove now-redundant checks around
is_assignment_op_expr_p.
* typeck.cc (convert_for_assignment): Look through implicit
INDIRECT_REF in -Wparentheses warning logic, and generalize
to use is_assignment_op_expr_p.
Do we want to factor out the whole warning logic rather than adjust it in both
places?
Sounds good, like so? Bootstrap / regtest in progress.
-- >8 --
Subject: [PATCH] c++: more ahead-of-time -Wparentheses warnings
Now that we don't have to worry about looking through NON_DEPENDENT_EXPR,
we can easily extend the -Wparentheses warning in convert_for_assignment
to consider (non-dependent) templated assignment operator expressions as
well, like r14-4111-g6e92a6a2a72d3b did in maybe_convert_cond.
gcc/cp/ChangeLog:
* cp-tree.h (maybe_warn_unparenthesized_assignment): Declare.
* semantics.cc (is_assignment_op_expr_p): Generalize to return
true for assignment operator expression, not just one that
have been resolved to an operator overload.
(maybe_warn_unparenthesized_assignment): Factored out from ...
(maybe_convert_cond): ... here.
(finish_parenthesized_expr): Also mention
maybe_warn_unparenthesized_assignment.
* typeck.cc (convert_for_assignment): Replace -Wparentheses
warning logic with maybe_warn_unparenthesized_assignment.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wparentheses-13.C: Strengthen by expecting that
the -Wparentheses warning are issued ahead of time.
* g++.dg/warn/Wparentheses-23.C: Likewise.
* g++.dg/warn/Wparentheses-32.C: Remove xfails.
---
gcc/cp/cp-tree.h | 1 +
gcc/cp/semantics.cc | 55 ++++++++++++++-------
gcc/cp/typeck.cc | 13 ++---
gcc/testsuite/g++.dg/warn/Wparentheses-13.C | 2 -
gcc/testsuite/g++.dg/warn/Wparentheses-23.C | 3 --
gcc/testsuite/g++.dg/warn/Wparentheses-32.C | 8 +--
6 files changed, 44 insertions(+), 38 deletions(-)
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 30fe716b109..98b29e9cf81 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7875,6 +7875,7 @@ extern tree lambda_regenerating_args (tree);
extern tree most_general_lambda (tree);
extern tree finish_omp_target (location_t, tree, tree, bool);
extern void finish_omp_target_clauses (location_t, tree, tree *);
+extern void maybe_warn_unparenthesized_assignment (tree, tsubst_flags_t);
/* in tree.cc */
extern int cp_tree_operand_length (const_tree);
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 72ec72de690..5664da9f4f2 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -840,15 +840,20 @@ finish_goto_stmt (tree destination)
return add_stmt (build_stmt (input_location, GOTO_EXPR, destination));
}
-/* Returns true if CALL is a (possibly wrapped) CALL_EXPR or AGGR_INIT_EXPR
- to operator= () that is written as an operator expression. */
+/* Returns true if T corresponds to an assignment operator expression. */
+
static bool
-is_assignment_op_expr_p (tree call)
+is_assignment_op_expr_p (tree t)
{
- if (call == NULL_TREE)
+ if (t == NULL_TREE)
return false;
- call = extract_call_expr (call);
+ if (TREE_CODE (t) == MODIFY_EXPR
+ || (TREE_CODE (t) == MODOP_EXPR
+ && TREE_CODE (TREE_OPERAND (t, 1)) == NOP_EXPR))
+ return true;
+
+ tree call = extract_call_expr (t);
if (call == NULL_TREE
|| call == error_mark_node
|| !CALL_EXPR_OPERATOR_SYNTAX (call))
@@ -860,6 +865,28 @@ is_assignment_op_expr_p (tree call)
&& DECL_OVERLOADED_OPERATOR_IS (fndecl, NOP_EXPR);
}
+/* Maybe warn about an unparenthesized 'a = b' (appearing in a boolean
+ context). */
+
+void
+maybe_warn_unparenthesized_assignment (tree t, tsubst_flags_t complain)
+{
+ t = REFERENCE_REF_P (t) ? TREE_OPERAND (t, 0) : t;
