Hi!
As the following testcase show (note, just for-{3,4,6,7,8}.C, constexpr-86769.C
and stmtexpr27.C FAIL without the patch, the rest is just that I couldn't
find coverage for some details and so added tests we don't regress or for5.C
is from Marek's attempt in the PR), we weren't correctly handling for/while
loops with declarations as conditions.
The C++ FE has the simplify_loop_decl_cond function which transforms
such loops as mentioned in the comment:
while (A x = 42) { }
for (; A x = 42;) { }
becomes
while (true) { A x = 42; if (!x) break; }
for (;;) { A x = 42; if (!x) break; }
For for loops this is not enough, as the x declaration should be
still in scope when expr (if any) is executed, and injecting the
expr expression into the body in the FE needs to have the continue
label in between, something normally added by the c-family
genericization. One of my thoughts was to just add there an artificial
label plus the expr expression in the FE and tell c-family about that
label, so that it doesn't create it but uses what has been emitted.
Unfortunately break/continue are resolved to labels only at c-family
genericization time and by moving the condition (and its preparation
statements such as the DECL_EXPR) into the body (and perhaps by also
moving there the (increment) expr as well) we resolve incorrectly any
break/continue statement appearing in cond (or newly perhaps also expr)
expression(s). While in standard C++ one can't have something like that
there, with statement expressions they are possible there, and we actually
have testsuite coverage that when they appear outside of the body of the
loop they bind to an outer loop rather than the inner one. When the FE
moves everything into the body, c-family can't distinguish any more between
the user body vs. the condition/preparation statements vs. expr expression.
So, the following patch instead keeps them separate and does the merging
only at the c-family loop genericization time. For that the patch
introduces two new operands of FOR_STMT and WHILE_STMT, *_COND_PREP
which is forced to be a BIND_EXPR which contains the preparation statements
like DECL_EXPR, and the initialization of that variable, so basically what
{FOR,WHILE}_BODY has when we encounter the function dealing with this,
except one optional CLEANUP_STMT at the end which holds cleanups for the
variable if it needs to be destructed. This CLEANUP_STMT is removed and
the actual cleanup saved into another new operand, *_COND_CLEANUP.
The c-family loop genericization handles such loops roughly the way
https://eel.is/c++draft/stmt.for and https://eel.is/c++draft/stmt.while
specifies, so the body is (if *_COND_CLEANUP is non-NULL)
{ A x = 42; try { if (!x) break; body; cont_label: expr; } finally { cleanup; }
}
and otherwise
{ A x = 42; if (!x) break; body; cont_label: expr; }
i.e. the *_COND, *_BODY, optional continue label, FOR_EXPR are appended
into the body of the *_COND_PREP BIND_EXPR.
And when doing constexpr evaluation of such FOR/WHILE loops, we treat
it similarly, first evaluate *_COND_PREP except the
for (tree decl = BIND_EXPR_VARS (t); decl; decl = DECL_CHAIN (decl))
destroy_value_checked (ctx, decl, non_constant_p);
part of BIND_EXPR handling for it, then evaluate *_COND (and decide based
on whether it was false or true like before), then *_BODY, then FOR_EXPR,
then *_COND_CLEANUP (similarly to the way how CLEANUP_STMT handling handles
that) and finally do those destroy_value_checked.
Note, the constexpr-86769.C testcase FAILs with both clang++ and MSVC (note,
the rest of tests PASS with clang++) but I believe it must be just a bug
in those compilers, new int is done in all the constructors and delete is
done in the destructor, so when clang++ reports one of the new int weren't
deallocated during constexpr evaluation I don't see how that would be
possible. When the same test has all the constexpr stuff, all the new int
are properly deleted at runtime when compiled by both compilers and valgrind
is happy about it, no leaks.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2025-02-05 Jakub Jelinek <ja...@redhat.com>
PR c++/86769
gcc/c-family/
* c-common.def (FOR_STMT): Add 2 operands and document them.
(WHILE_STMT): Likewise.
* c-common.h (WHILE_COND_PREP, WHILE_COND_CLEANUP): Define.
(FOR_COND_PREP, FOR_COND_CLEANUP): Define.
* c-gimplify.cc (genericize_c_loop): Add COND_PREP and COND_CLEANUP
arguments, handle them if they are non-NULL.
(genericize_for_stmt, genericize_while_stmt, genericize_do_stmt):
Adjust callers.
gcc/c/
* c-parser.cc (c_parser_while_statement): Add 2 further NULL_TREE
operands to build_stmt.
(c_parser_for_statement): Likewise.
gcc/cp/
* semantics.cc (simplify_loop_decl_cond): Remove.
(adjust_loop_decl_cond): New function.
(begin_while_stmt): Add 2 further NULL_TREE operands to build_stmt.
(finish_while_stmt_cond): Call adjust_loop_decl_cond instead of
simplify_loop_decl_cond.
(set_cond_cleanup_locs): New function.
(finish_while_stmt): Call do_poplevel also on WHILE_COND_PREP if
non-NULL and also use pop_stmt_list rather than do_poplevel for
WHILE_BODY in that case. Call set_cond_cleanup_locs.
(begin_for_stmt): Add 2 further NULL_TREE operands to build_stmt.
(finish_for_cond): Call adjust_loop_decl_cond instead of
simplify_loop_decl_cond.
(finish_for_stmt): Call do_poplevel also on FOR_COND_PREP if non-NULL
and also use pop_stmt_list rather than do_poplevel for FOR_BODY in
that case. Call set_cond_cleanup_locs.
* constexpr.cc (cxx_eval_loop_expr): Handle
{WHILE,FOR}_COND_{PREP,CLEANUP}.
(check_for_return_continue): Handle {WHILE,FOR}_COND_PREP.
(potential_constant_expression_1): RECUR on
{WHILE,FOR}_COND_{PREP,CLEANUP}.
gcc/testsuite/
* g++.dg/diagnostic/redeclaration-7.C: New test.
* g++.dg/expr/for3.C: New test.
* g++.dg/expr/for4.C: New test.
* g++.dg/expr/for5.C: New test.
* g++.dg/expr/for6.C: New test.
* g++.dg/expr/for7.C: New test.
* g++.dg/expr/for8.C: New test.
* g++.dg/ext/stmtexpr27.C: New test.
* g++.dg/cpp2a/constexpr-86769.C: New test.
* g++.dg/cpp26/name-independent-decl7.C: New test.
* g++.dg/cpp26/name-independent-decl8.C: New test.
--- gcc/c-family/c-common.def.jj 2025-01-02 20:54:31.716135638 +0100
+++ gcc/c-family/c-common.def 2025-02-04 21:55:01.446717375 +0100
@@ -58,13 +58,14 @@ DEFTREECODE (SIZEOF_EXPR, "sizeof_expr",
DEFTREECODE (PAREN_SIZEOF_EXPR, "paren_sizeof_expr", tcc_expression, 1)
/* Used to represent a `for' statement. The operands are
- FOR_INIT_STMT, FOR_COND, FOR_EXPR, FOR_BODY, FOR_SCOPE, and FOR_NAME
- respectively. */
-DEFTREECODE (FOR_STMT, "for_stmt", tcc_statement, 6)
+ FOR_INIT_STMT, FOR_COND, FOR_EXPR, FOR_BODY, FOR_SCOPE, FOR_NAME,
+ FOR_COND_PREP and FOR_COND_CLEANUP, respectively. */
+DEFTREECODE (FOR_STMT, "for_stmt", tcc_statement, 8)
/* Used to represent a 'while' statement. The operands are WHILE_COND,
- WHILE_BODY, and WHILE_NAME, respectively. */
-DEFTREECODE (WHILE_STMT, "while_stmt", tcc_statement, 3)
+ WHILE_BODY, WHILE_NAME, WHILE_COND_PREP and WHILE_COND_CLEANUP,
+ respectively. */
+DEFTREECODE (WHILE_STMT, "while_stmt", tcc_statement, 5)
/* Used to represent a 'do' statement. The operands are DO_COND, DO_BODY,
and DO_NAME, respectively. */
--- gcc/c-family/c-common.h.jj 2025-01-22 21:23:31.001840267 +0100
+++ gcc/c-family/c-common.h 2025-02-04 21:55:01.448717347 +0100
@@ -1517,10 +1517,13 @@ extern tree build_userdef_literal (tree
/* WHILE_STMT accessors. These give access to the condition of the
- while statement, the body and name of the while statement, respectively. */
+ while statement, the body, and name of the while statement, and
+ condition preparation statements and its cleanup, respectively. */
#define WHILE_COND(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 0)
#define WHILE_BODY(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 1)
#define WHILE_NAME(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 2)
+#define WHILE_COND_PREP(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 3)
+#define WHILE_COND_CLEANUP(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 4)
/* DO_STMT accessors. These give access to the condition of the do
statement, the body and name of the do statement, respectively. */
@@ -1530,13 +1533,15 @@ extern tree build_userdef_literal (tree
/* FOR_STMT accessors. These give access to the init statement,
condition, update expression, body and name of the for statement,
- respectively. */
+ and condition preparation statements and its cleanup, respectively. */
#define FOR_INIT_STMT(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 0)
#define FOR_COND(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 1)
#define FOR_EXPR(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 2)
#define FOR_BODY(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 3)
#define FOR_SCOPE(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 4)
#define FOR_NAME(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 5)
+#define FOR_COND_PREP(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 6)
+#define FOR_COND_CLEANUP(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 7)
/* BREAK_STMT accessors. */
#define BREAK_NAME(NODE) TREE_OPERAND (BREAK_STMT_CHECK (NODE), 0)
--- gcc/c-family/c-gimplify.cc.jj 2025-01-16 21:35:00.140478355 +0100
+++ gcc/c-family/c-gimplify.cc 2025-02-05 10:35:13.147724490 +0100
@@ -254,24 +254,31 @@ expr_loc_or_loc (const_tree expr, locati
controlled by the loop. INCR is the increment expression of a for-loop,
or NULL_TREE. COND_IS_FIRST indicates whether the condition is
evaluated before the loop body as in while and for loops, or after the
- loop body as in do-while loops. */
+ loop body as in do-while loops. COND_PREP and COND_CLEANUP are used
+ for C++ for/while loops with variable declaration as condition. COND_PREP
+ is a BIND_EXPR with the declaration and preparation statements, into which
+ COND, BODY, continue label if needed and INCR if non-NULL should be
+ appended, and COND_CLEANUP are statements which should be evaluated after
+ that or if anything in COND, BODY or INCR throws. */
static void
genericize_c_loop (tree *stmt_p, location_t start_locus, tree cond, tree body,
- tree incr, tree name, bool cond_is_first,
- int *walk_subtrees, void *data, walk_tree_fn func,
- walk_tree_lh lh)
+ tree incr, tree name, tree cond_prep, tree cond_cleanup,
+ bool cond_is_first, int *walk_subtrees, void *data,
+ walk_tree_fn func, walk_tree_lh lh)
{
tree blab, clab;
tree entry = NULL, exit = NULL, t;
- tree stmt_list = NULL;
+ tree stmt_list = NULL, outer_stmt_list = NULL_TREE, *stmt_list_p = NULL;
location_t cond_locus = expr_loc_or_loc (cond, start_locus);
location_t incr_locus = expr_loc_or_loc (incr, start_locus);
protected_set_expr_location_if_unset (incr, start_locus);
+ walk_tree_1 (&cond_prep, func, data, NULL, lh);
walk_tree_1 (&cond, func, data, NULL, lh);
walk_tree_1 (&incr, func, data, NULL, lh);
+ walk_tree_1 (&cond_cleanup, func, data, NULL, lh);
blab = begin_bc_block (bc_break, start_locus);
clab = begin_bc_block (bc_continue, start_locus);
@@ -284,9 +291,66 @@ genericize_c_loop (tree *stmt_p, locatio
if (name)
release_named_bc (name);
- /* If condition is zero don't generate a loop construct. */
- if (cond && integer_zerop (cond))
+ if (cond_prep)
{
+ /* The C++ cases of
+ while (A x = 42) body;
+ for (; A x = 42; expr) body;
+ This should be expanded into:
+
+ top:
+ COND_PREP
+
+ with either
+
+ if (COND); else break;
+ BODY;
+ cont:
+ EXPR;
+ goto top;
+
+ or
+
+ try {
+ if (COND); else break;
+ BODY;
+ cont:
+ EXPR;
+ } finally {
+ COND_CLEANUP
+ }
+
+ appended into COND_PREP body. */
+ gcc_assert (cond_is_first && TREE_CODE (cond_prep) == BIND_EXPR);
+ tree top = build1 (LABEL_EXPR, void_type_node,
+ create_artificial_label (start_locus));
+ append_to_statement_list (top, &outer_stmt_list);
+ append_to_statement_list (cond_prep, &outer_stmt_list);
+ stmt_list = BIND_EXPR_BODY (cond_prep);
+ BIND_EXPR_BODY (cond_prep) = NULL_TREE;
+ stmt_list_p = &BIND_EXPR_BODY (cond_prep);
+ if (cond_cleanup && TREE_SIDE_EFFECTS (cond_cleanup))
+ {
+ t = build2_loc (EXPR_LOCATION (cond_cleanup), TRY_FINALLY_EXPR,
+ void_type_node, NULL_TREE, cond_cleanup);
+ append_to_statement_list (t, &stmt_list);
+ *stmt_list_p = stmt_list;
+ stmt_list_p = &TREE_OPERAND (t, 0);
+ stmt_list = NULL_TREE;
+ }
+ exit = build1 (GOTO_EXPR, void_type_node, LABEL_EXPR_LABEL (top));
+ tree after_cond = create_artificial_label (cond_locus);
+ tree goto_after_cond = build1 (GOTO_EXPR, void_type_node, after_cond);
+ t = build1 (GOTO_EXPR, void_type_node, get_bc_label (bc_break));
+ t = fold_build3_loc (cond_locus, COND_EXPR, void_type_node, cond,
+ goto_after_cond, t);
+ append_to_statement_list (t, &stmt_list);
+ t = build1 (LABEL_EXPR, void_type_node, after_cond);
+ append_to_statement_list (t, &stmt_list);
+ }
+ else if (cond && integer_zerop (cond))
+ {
+ /* If condition is zero don't generate a loop construct. */
if (cond_is_first)
{
t = build1_loc (start_locus, GOTO_EXPR, void_type_node,
@@ -383,6 +447,11 @@ genericize_c_loop (tree *stmt_p, locatio
append_to_statement_list (d, &stmt_list);
}
append_to_statement_list (exit, &stmt_list);
+ if (cond_prep)
+ {
+ *stmt_list_p = stmt_list;
+ stmt_list = outer_stmt_list;
+ }
finish_bc_block (&stmt_list, bc_break, blab);
if (!stmt_list)
stmt_list = build_empty_stmt (start_locus);
@@ -408,7 +477,8 @@ genericize_for_stmt (tree *stmt_p, int *
}
genericize_c_loop (&loop, EXPR_LOCATION (stmt), FOR_COND (stmt),
- FOR_BODY (stmt), FOR_EXPR (stmt), FOR_NAME (stmt), 1,
+ FOR_BODY (stmt), FOR_EXPR (stmt), FOR_NAME (stmt),
+ FOR_COND_PREP (stmt), FOR_COND_CLEANUP (stmt), 1,
walk_subtrees, data, func, lh);
append_to_statement_list (loop, &expr);
if (expr == NULL_TREE)
@@ -424,7 +494,8 @@ genericize_while_stmt (tree *stmt_p, int
{
tree stmt = *stmt_p;
genericize_c_loop (stmt_p, EXPR_LOCATION (stmt), WHILE_COND (stmt),
- WHILE_BODY (stmt), NULL_TREE, WHILE_NAME (stmt), 1,
+ WHILE_BODY (stmt), NULL_TREE, WHILE_NAME (stmt),
+ WHILE_COND_PREP (stmt), WHILE_COND_CLEANUP (stmt), 1,
walk_subtrees, data, func, lh);
}
@@ -436,8 +507,8 @@ genericize_do_stmt (tree *stmt_p, int *w
{
tree stmt = *stmt_p;
genericize_c_loop (stmt_p, EXPR_LOCATION (stmt), DO_COND (stmt),
- DO_BODY (stmt), NULL_TREE, DO_NAME (stmt), 0,
- walk_subtrees, data, func, lh);
+ DO_BODY (stmt), NULL_TREE, DO_NAME (stmt),
+ NULL_TREE, NULL_TREE, 0, walk_subtrees, data, func, lh);
}
/* Genericize a SWITCH_STMT node *STMT_P by turning it into a SWITCH_EXPR. */
--- gcc/c/c-parser.cc.jj 2025-01-30 22:09:17.463383671 +0100
+++ gcc/c/c-parser.cc 2025-02-04 21:55:01.454717262 +0100
@@ -8802,7 +8802,8 @@ c_parser_while_statement (c_parser *pars
body = c_parser_c99_block_statement (parser, if_p, &loc_after_labels);
if (loop_name && !C_DECL_LOOP_SWITCH_NAME_USED (loop_name))
loop_name = NULL_TREE;
- add_stmt (build_stmt (loc, WHILE_STMT, cond, body, loop_name));
+ add_stmt (build_stmt (loc, WHILE_STMT, cond, body, loop_name, NULL_TREE,
+ NULL_TREE));
add_stmt (c_end_compound_stmt (loc, block, flag_isoc99));
c_parser_maybe_reclassify_token (parser);
if (num_names)
@@ -9207,7 +9208,7 @@ c_parser_for_statement (c_parser *parser
add_stmt (build_stmt (for_loc, FOR_STMT, NULL_TREE, cond, incr,
body, NULL_TREE,
loop_name && C_DECL_LOOP_SWITCH_NAME_USED (loop_name)
- ? loop_name : NULL_TREE));
+ ? loop_name : NULL_TREE, NULL_TREE, NULL_TREE));
add_stmt (c_end_compound_stmt (for_loc, block,
flag_isoc99 || c_dialect_objc ()));
c_parser_maybe_reclassify_token (parser);
--- gcc/cp/semantics.cc.jj 2025-02-04 21:54:35.115087765 +0100
+++ gcc/cp/semantics.cc 2025-02-05 10:35:13.146724504 +0100
@@ -777,37 +777,48 @@ finish_cond (tree *cond_p, tree expr)
*cond_p = expr;
}
-/* If *COND_P specifies a conditional with a declaration, transform the
- loop such that
+/* If loop condition specifies a conditional with a declaration,
+ such as
while (A x = 42) { }
for (; A x = 42;) { }
- becomes
- while (true) { A x = 42; if (!x) break; }
- for (;;) { A x = 42; if (!x) break; }
- The statement list for BODY will be empty if the conditional did
+ move the *BODY_P statements as a BIND_EXPR into {FOR,WHILE}_COND_PREP
+ and if there is any CLEANUP_STMT at the end, remove that and
+ put the cleanup into {FOR,WHILE}_COND_CLEANUP.
+ genericize_c_loop will then handle it appropriately. In particular,
+ the {FOR,WHILE}_COND, {FOR,WHILE}_BODY, if used continue label and
+ FOR_EXPR will be appended into the {FOR,WHILE}_COND_PREP BIND_EXPR,
+ but it can't be done too early because only the actual body should
+ bind BREAK_STMT and CONTINUE_STMT to the inner loop.
+ The statement list for *BODY will be empty if the conditional did
not declare anything. */
static void
-simplify_loop_decl_cond (tree *cond_p, tree body)
+adjust_loop_decl_cond (tree *body_p, tree *prep_p, tree *cleanup_p)
{
- tree cond, if_stmt;
-
- if (!TREE_SIDE_EFFECTS (body))
+ if (!TREE_SIDE_EFFECTS (*body_p))
return;
- cond = *cond_p;
- *cond_p = boolean_true_node;
-
- if_stmt = begin_if_stmt ();
- cond_p = &cond;
- while (TREE_CODE (*cond_p) == ANNOTATE_EXPR)
- cond_p = &TREE_OPERAND (*cond_p, 0);
- *cond_p = cp_build_unary_op (TRUTH_NOT_EXPR, *cond_p, false,
- tf_warning_or_error);
- finish_if_stmt_cond (cond, if_stmt);
- finish_break_stmt ();
- finish_then_clause (if_stmt);
- finish_if_stmt (if_stmt);
+ gcc_assert (!processing_template_decl);
+ if (*body_p != cur_stmt_list)
+ {
+ /* There can be either no cleanup at all, if the condition
+ declaration doesn't have non-trivial destructor, or a single
+ one if it does. In that case extract it into *CLEANUP_P. */
+ gcc_assert (stmt_list_stack->length () > 1
+ && (*stmt_list_stack)[stmt_list_stack->length ()
+ - 2] == *body_p);
+ tree_stmt_iterator last = tsi_last (*body_p);
+ gcc_assert (tsi_one_before_end_p (last)
+ && TREE_CODE (tsi_stmt (last)) == CLEANUP_STMT
+ && CLEANUP_BODY (tsi_stmt (last)) == cur_stmt_list
+ && tsi_end_p (tsi_last (cur_stmt_list))
+ && !CLEANUP_EH_ONLY (tsi_stmt (last)));
+ *cleanup_p = CLEANUP_EXPR (tsi_stmt (last));
+ tsi_delink (&last);
+ }
+ current_binding_level->keep = true;
+ *prep_p = *body_p;
+ *body_p = push_stmt_list ();
}
/* Finish a goto-statement. */
@@ -1368,7 +1379,8 @@ tree
begin_while_stmt (void)
{
tree r;
- r = build_stmt (input_location, WHILE_STMT, NULL_TREE, NULL_TREE, NULL_TREE);
+ r = build_stmt (input_location, WHILE_STMT, NULL_TREE, NULL_TREE, NULL_TREE,
+ NULL_TREE, NULL_TREE);
add_stmt (r);
WHILE_BODY (r) = do_pushlevel (sk_block);
begin_cond (&WHILE_COND (r));
@@ -1406,7 +1418,25 @@ finish_while_stmt_cond (tree cond, tree
build_int_cst (integer_type_node,
annot_expr_no_vector_kind),
integer_zero_node);
- simplify_loop_decl_cond (&WHILE_COND (while_stmt), WHILE_BODY (while_stmt));
+ adjust_loop_decl_cond (&WHILE_BODY (while_stmt),
+ &WHILE_COND_PREP (while_stmt),
+ &WHILE_COND_CLEANUP (while_stmt));
+}
+
+/* Set EXPR_LOCATION of the {FOR,WHILE}_COND_CLEANUP to LOC. */
+
+static void
+set_cond_cleanup_locs (tree cond_cleanup, location_t loc)
+{
+ if (cond_cleanup)
+ {
+ if (TREE_CODE (cond_cleanup) != POSTCONDITION_STMT)
+ protected_set_expr_location (cond_cleanup, loc);
+ if (TREE_CODE (cond_cleanup) == NOP_EXPR
+ && TREE_TYPE (cond_cleanup) == void_type_node
+ && TREE_CODE (TREE_OPERAND (cond_cleanup, 0)) == CALL_EXPR)
+ protected_set_expr_location (TREE_OPERAND (cond_cleanup, 0), loc);
+ }
}
/* Finish a while-statement, which may be given by WHILE_STMT. */
@@ -1415,8 +1445,14 @@ void
finish_while_stmt (tree while_stmt)
{
end_maybe_infinite_loop (boolean_true_node);
- WHILE_BODY (while_stmt) = do_poplevel (WHILE_BODY (while_stmt));
+ WHILE_BODY (while_stmt)
+ = (WHILE_COND_PREP (while_stmt)
+ ? pop_stmt_list (WHILE_BODY (while_stmt))
+ : do_poplevel (WHILE_BODY (while_stmt)));
finish_loop_cond (&WHILE_COND (while_stmt), WHILE_BODY (while_stmt));
+ if (WHILE_COND_PREP (while_stmt))
+ WHILE_COND_PREP (while_stmt) = do_poplevel (WHILE_COND_PREP (while_stmt));
+ set_cond_cleanup_locs (WHILE_COND_CLEANUP (while_stmt), input_location);
}
/* Begin a do-statement. Returns a newly created DO_STMT if
@@ -1547,7 +1583,8 @@ begin_for_stmt (tree scope, tree init)
tree r;
r = build_stmt (input_location, FOR_STMT, NULL_TREE, NULL_TREE,
- NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE);
+ NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE,
+ NULL_TREE, NULL_TREE);
if (scope == NULL_TREE)
{
@@ -1605,7 +1642,8 @@ finish_for_cond (tree cond, tree for_stm
build_int_cst (integer_type_node,
annot_expr_no_vector_kind),
integer_zero_node);
- simplify_loop_decl_cond (&FOR_COND (for_stmt), FOR_BODY (for_stmt));
+ adjust_loop_decl_cond (&FOR_BODY (for_stmt), &FOR_COND_PREP (for_stmt),
+ &FOR_COND_CLEANUP (for_stmt));
}
/* Finish the increment-EXPRESSION in a for-statement, which may be
@@ -1679,11 +1717,17 @@ finish_for_stmt (tree for_stmt)
RANGE_FOR_BODY (for_stmt) = do_poplevel (RANGE_FOR_BODY (for_stmt));
else
{
- FOR_BODY (for_stmt) = do_poplevel (FOR_BODY (for_stmt));
+ FOR_BODY (for_stmt)
+ = (FOR_COND_PREP (for_stmt)
+ ? pop_stmt_list (FOR_BODY (for_stmt))
+ : do_poplevel (FOR_BODY (for_stmt)));
if (FOR_COND (for_stmt))
finish_loop_cond (&FOR_COND (for_stmt),
FOR_EXPR (for_stmt) ? integer_one_node
: FOR_BODY (for_stmt));
+ if (FOR_COND_PREP (for_stmt))
+ FOR_COND_PREP (for_stmt) = do_poplevel (FOR_COND_PREP (for_stmt));
+ set_cond_cleanup_locs (FOR_COND_CLEANUP (for_stmt), input_location);
}
/* Pop the scope for the body of the loop. */
--- gcc/cp/constexpr.cc.jj 2025-01-30 22:09:17.476383491 +0100
+++ gcc/cp/constexpr.cc 2025-02-04 21:55:01.459717192 +0100
@@ -7152,7 +7152,9 @@ cxx_eval_loop_expr (const constexpr_ctx
}
tree body, cond = NULL_TREE, expr = NULL_TREE;
+ tree cond_prep = NULL_TREE, cond_cleanup = NULL_TREE;
int count = 0;
+ location_t loc = cp_expr_loc_or_input_loc (t);
switch (TREE_CODE (t))
{
case LOOP_EXPR:
@@ -7165,6 +7167,8 @@ cxx_eval_loop_expr (const constexpr_ctx
case WHILE_STMT:
body = WHILE_BODY (t);
cond = WHILE_COND (t);
+ cond_prep = WHILE_COND_PREP (t);
+ cond_cleanup = WHILE_COND_CLEANUP (t);
count = -1;
break;
case FOR_STMT:
@@ -7176,11 +7180,15 @@ cxx_eval_loop_expr (const constexpr_ctx
body = FOR_BODY (t);
cond = FOR_COND (t);
expr = FOR_EXPR (t);
+ cond_prep = FOR_COND_PREP (t);
+ cond_cleanup = FOR_COND_CLEANUP (t);
count = -1;
break;
default:
gcc_unreachable ();
}
+ if (cond_prep)
+ gcc_assert (TREE_CODE (cond_prep) == BIND_EXPR);
do
{
if (count != -1)
@@ -7202,6 +7210,28 @@ cxx_eval_loop_expr (const constexpr_ctx
cxx_eval_constant_expression (ctx, expr, vc_prvalue,
non_constant_p, overflow_p,
jump_target);
+
+ if (cond_cleanup && !*non_constant_p)
+ {
+ iloc_sentinel ils (loc);
+ /* Also evaluate the cleanup. */
+ cxx_eval_constant_expression (ctx, cond_cleanup, vc_discard,
+ non_constant_p, overflow_p);
+ }
+ if (cond_prep)
+ for (tree decl = BIND_EXPR_VARS (cond_prep);
+ decl; decl = DECL_CHAIN (decl))
+ destroy_value_checked (ctx, decl, non_constant_p);
+ }
+
+ if (cond_prep)
+ {
+ for (tree decl = BIND_EXPR_VARS (cond_prep);
+ decl; decl = DECL_CHAIN (decl))
+ ctx->global->clear_value (decl);
+ cxx_eval_constant_expression (ctx, BIND_EXPR_BODY (cond_prep),
+ vc_discard, non_constant_p,
+ overflow_p, jump_target);
}
if (cond)
@@ -7239,6 +7269,18 @@ cxx_eval_loop_expr (const constexpr_ctx
&& (!switches (jump_target) || count == 0)
&& !*non_constant_p);
+ if (cond_cleanup && !*non_constant_p)
+ {
+ iloc_sentinel ils (loc);
+ /* Also evaluate the cleanup. */
+ cxx_eval_constant_expression (ctx, cond_cleanup, vc_discard,
+ non_constant_p, overflow_p);
+ }
+ if (cond_prep)
+ for (tree decl = BIND_EXPR_VARS (cond_prep);
+ decl; decl = DECL_CHAIN (decl))
+ destroy_value_checked (ctx, decl, non_constant_p);
+
return NULL_TREE;
}
@@ -9618,6 +9660,7 @@ check_for_return_continue (tree *tp, int
case WHILE_STMT:
*walk_subtrees = 0;
+ RECUR (WHILE_COND_PREP (t));
RECUR (WHILE_COND (t));
s = d->continue_stmt;
b = d->break_stmt;
@@ -9629,6 +9672,7 @@ check_for_return_continue (tree *tp, int
case FOR_STMT:
*walk_subtrees = 0;
RECUR (FOR_INIT_STMT (t));
+ RECUR (FOR_COND_PREP (t));
RECUR (FOR_COND (t));
RECUR (FOR_EXPR (t));
s = d->continue_stmt;
@@ -10132,6 +10176,8 @@ potential_constant_expression_1 (tree t,
case FOR_STMT:
if (!RECUR (FOR_INIT_STMT (t), any))
return false;
+ if (!RECUR (FOR_COND_PREP (t), any))
+ return false;
tmp = FOR_COND (t);
if (!RECUR (tmp, rval))
return false;
@@ -10159,6 +10205,8 @@ potential_constant_expression_1 (tree t,
return false;
if (!RECUR (FOR_BODY (t), any))
return false;
+ if (!RECUR (FOR_COND_CLEANUP (t), any))
+ return false;
if (breaks (jump_target) || continues (jump_target))
*jump_target = NULL_TREE;
return true;
@@ -10175,6 +10223,8 @@ potential_constant_expression_1 (tree t,
return true;
case WHILE_STMT:
+ if (!RECUR (WHILE_COND_PREP (t), any))
+ return false;
tmp = WHILE_COND (t);
if (!RECUR (tmp, rval))
return false;
@@ -10196,6 +10246,8 @@ potential_constant_expression_1 (tree t,
}
if (!RECUR (WHILE_BODY (t), any))
return false;
+ if (!RECUR (WHILE_COND_CLEANUP (t), any))
+ return false;
if (breaks (jump_target) || continues (jump_target))
*jump_target = NULL_TREE;
return true;
--- gcc/testsuite/g++.dg/diagnostic/redeclaration-7.C.jj 2025-02-05
11:55:21.121278657 +0100
+++ gcc/testsuite/g++.dg/diagnostic/redeclaration-7.C 2025-02-05
12:01:14.196302369 +0100
@@ -0,0 +1,23 @@
+// PR c++/52953
+// { dg-do compile }
+// { dg-options "-pedantic-errors" }
+
+volatile int v;
+
+void
+baz ()
+{
+ for (int x = v; // { dg-message "'int x' previously
declared here" }
+ int x = v; ++x) // { dg-error "redeclaration of 'int
x'" }
+ ;
+ for (int x = v; // { dg-message "'int x' previously
declared here" }
+ int x = v; ++x) // { dg-error "redeclaration of 'int
x'" }
+ { // { dg-message "'int x' previously
declared here" "" { target *-*-* } .-1 }
+ int x; // { dg-error "redeclaration of 'int
x'" }
+ }
+ for (int x = v; // { dg-message "'int x' previously
declared here" }
+ int x = v; ++x) // { dg-error "redeclaration of 'int
x'" }
+ { // { dg-message "previous declaration
'int x'" "" { target *-*-* } .-1 }
+ extern int x; // { dg-error "'int x' conflicts with a
previous declaration" }
+ }
+}
--- gcc/testsuite/g++.dg/expr/for3.C.jj 2025-02-04 21:55:01.459717192 +0100
+++ gcc/testsuite/g++.dg/expr/for3.C 2025-02-04 21:55:01.459717192 +0100
@@ -0,0 +1,112 @@
+// PR c++/86769
+// { dg-do run { target c++11 } }
+
+int d, e, f, g, h;
+struct A {
+ int a;
+ A (int x) : a(x) { ++d; ++h; }
+ ~A () { --d; ++h; }
+ A (const A &x) : a(x.a) { ++d; ++h; }
+ operator bool () { return a != 0; }
+};
+struct B {
+ B () { ++e; ++h; }
+ ~B () { --e; ++h; }
+ B (const B &) { ++e; ++h; }
+};
+
+int
+foo (B, int x)
+{
+ if (e != 1)
+ __builtin_abort ();
+ if (f ? x - 1 != (f - 1) % 3 : x)
+ __builtin_abort ();
+ ++f;
+ if (x == 1)
+ return ++g < 3;
+ return 0;
+}
+
+int
+bar (int n)
+{
+ if (e != 0 || d != n)
+ __builtin_abort ();
+ return 0;
+}
+
+int
+main ()
+{
+ for (A a = (bar (0), foo (B {}, 0));
+ A b = (bar (1), foo (B {}, 1));
+ bar (2), foo (B {}, 3))
+ A c = (bar (2), foo (B {}, 2));
+ if (f != 8 || h != 28 || d || e)
+ __builtin_abort ();
+ f = 0; g = -2; h = 0;
+ for (A a = (bar (0), foo (B {}, 0));
+ A b = (bar (1), foo (B {}, 1));
+ bar (2), foo (B {}, 3))
+ {
+ A c = (bar (2), foo (B {}, 2));
+ bar (3);
+ }
+ if (f != 14 || h != 48 || d || e)
+ __builtin_abort ();
+ f = 0; g = 0; h = 0;
+ {
+ A a = (bar (0), foo (B {}, 0));
+ while (A b = (bar (1), foo (B {}, 1)))
+ {
+ A c = (bar (2), foo (B {}, 2));
+ bar (3);
+ foo (B {}, 3);
+ }
+ }
+ if (f != 8 || h != 28 || d || e)
+ __builtin_abort ();
+ f = 0; g = -5; h = 0;
+ for (A a = (bar (0), foo (B {}, 0));
+ A b = (bar (1), foo (B {}, 1));
+ bar (2), foo (B {}, 3))
+ {
+ if (f == 5)
+ {
+ bar (2);
+ foo (B {}, 2);
+ bar (2);
+ continue;
+ }
+ if (f == 11)
+ break;
+ A c = (bar (2), foo (B {}, 2));
+ bar (3);
+ }
+ if (f != 11 || h != 36 || d || e)
+ __builtin_abort ();
+ f = 0; g = -5; h = 0;
+ {
+ A a = (bar (0), foo (B {}, 0));
+ while (A b = (bar (1), foo (B {}, 1)))
+ {
+ if (f == 5)
+ {
+ bar (2);
+ foo (B {}, 2);
+ bar (2);
+ foo (B {}, 3);
+ bar (2);
+ continue;
+ }
+ else if (f == 11)
+ break;
+ A c = (bar (2), foo (B {}, 2));
+ bar (3);
+ foo (B {}, 3);
+ }
+ }
+ if (f != 11 || h != 36 || d || e)
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/expr/for4.C.jj 2025-02-04 21:55:01.460717178 +0100
+++ gcc/testsuite/g++.dg/expr/for4.C 2025-02-04 21:55:01.460717178 +0100
@@ -0,0 +1,116 @@
+// PR c++/86769
+// { dg-do run }
+
+int d, e, f, g, h;
+struct A {
+ int a;
+ A (int x) : a(x) { ++d; ++h; }
+ ~A () { --d; ++h; }
+ A (const A &x) : a(x.a) { ++d; ++h; }
+ operator bool () { return a != 0; }
+};
+struct B {
+ B () { ++e; ++h; }
+ ~B () { --e; ++h; }
+ B (const B &) { ++e; ++h; }
+};
+B k;
+
+int
+foo (B, int x)
+{
+ if (e != 1)
+ __builtin_abort ();
+ if (f ? x - 1 != (f - 1) % 3 : x)
+ __builtin_abort ();
+ ++f;
+ if (x == 1)
+ return ++g < 3;
+ return 0;
+}
+
+int
+bar (int n)
+{
+ if (e != 0 || d != n)
+ __builtin_abort ();
+ return 0;
+}
+
+int
+main ()
+{
+ if (e != 1 || h != 1)
+ __builtin_abort ();
+ e = 0; h = 0;
+ for (A a = (bar (0), foo (k, 0));
+ A b = (bar (1), foo (k, 1));
+ bar (2), foo (k, 3))
+ A c = (bar (2), foo (k, 2));
+ if (f != 8 || h != 28 || d || e)
+ __builtin_abort ();
+ f = 0; g = -2; h = 0;
+ for (A a = (bar (0), foo (k, 0));
+ A b = (bar (1), foo (k, 1));
+ bar (2), foo (k, 3))
+ {
+ A c = (bar (2), foo (k, 2));
+ bar (3);
+ }
+ if (f != 14 || h != 48 || d || e)
+ __builtin_abort ();
+ f = 0; g = 0; h = 0;
+ {
+ A a = (bar (0), foo (k, 0));
+ while (A b = (bar (1), foo (k, 1)))
+ {
+ A c = (bar (2), foo (k, 2));
+ bar (3);
+ foo (k, 3);
+ }
+ }
+ if (f != 8 || h != 28 || d || e)
+ __builtin_abort ();
+ f = 0; g = -5; h = 0;
+ for (A a = (bar (0), foo (k, 0));
+ A b = (bar (1), foo (k, 1));
+ bar (2), foo (k, 3))
+ {
+ if (f == 5)
+ {
+ bar (2);
+ foo (k, 2);
+ bar (2);
+ continue;
+ }
+ if (f == 11)
+ break;
+ A c = (bar (2), foo (k, 2));
+ bar (3);
+ }
+ if (f != 11 || h != 36 || d || e)
+ __builtin_abort ();
+ f = 0; g = -5; h = 0;
+ {
+ A a = (bar (0), foo (k, 0));
+ while (A b = (bar (1), foo (k, 1)))
+ {
+ if (f == 5)
+ {
+ bar (2);
+ foo (k, 2);
+ bar (2);
+ foo (k, 3);
+ bar (2);
+ continue;
+ }
+ else if (f == 11)
+ break;
+ A c = (bar (2), foo (k, 2));
+ bar (3);
+ foo (k, 3);
+ }
+ }
+ if (f != 11 || h != 36 || d || e)
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/expr/for5.C.jj 2025-02-04 21:55:01.460717178 +0100
+++ gcc/testsuite/g++.dg/expr/for5.C 2025-02-04 21:55:01.460717178 +0100
@@ -0,0 +1,34 @@
+// PR c++/86769
+// { dg-do run }
+
+int g;
+
+struct X {
+ X () { g++; }
+ ~X () { g--; }
+ operator bool () { return g == 0; }
+};
+
+void
+foo ()
+{
+ if (g <= 0)
+ __builtin_abort ();
+}
+
+void
+bar ()
+{
+ if (g)
+ __builtin_abort ();
+}
+
+int
+main ()
+{
+ for (int i = 0; i < 1; ++i, bar ())
+ {
+ X x = X ();
+ foo ();
+ }
+}
--- gcc/testsuite/g++.dg/expr/for6.C.jj 2025-02-04 21:55:01.460717178 +0100
+++ gcc/testsuite/g++.dg/expr/for6.C 2025-02-04 21:55:01.460717178 +0100
@@ -0,0 +1,39 @@
+// PR c++/86769
+// { dg-do run { target c++11 } }
+
+int v;
+
+struct S {
+ int s;
+ S (int x) : s(x)
+ {
+ if ((v != 0 || s != 0) && (v != 3 || s != 1))
+ __builtin_abort ();
+ ++v;
+ }
+ ~S ()
+ {
+ if ((v != 2 || s != 0) && (v != 4 || s != 1))
+ __builtin_abort ();
+ ++v;
+ }
+ operator bool () const { return true; }
+};
+
+void
+foo (const S &s)
+{
+ if (v != 1 || s.s != 0)
+ __builtin_abort ();
+ ++v;
+}
+
+int
+main ()
+{
+ for (int i = 0; S j{i}; foo (j))
+ {
+ if (++i == 2)
+ break;
+ }
+}
--- gcc/testsuite/g++.dg/expr/for7.C.jj 2025-02-04 21:55:01.460717178 +0100
+++ gcc/testsuite/g++.dg/expr/for7.C 2025-02-04 21:55:01.460717178 +0100
@@ -0,0 +1,20 @@
+// PR c++/86769
+// { dg-do run }
+
+int v;
+
+struct S
+{
+ S (int x) : s(x) { v++; }
+ ~S () { v--; }
+ int s;
+ operator int () { if (!v) __builtin_abort (); return s; }
+};
+
+int
+main ()
+{
+ int x = 10;
+ for (int l = 1; S d = x - l; l = d + 1)
+ ;
+}
--- gcc/testsuite/g++.dg/expr/for8.C.jj 2025-02-04 21:55:01.460717178 +0100
+++ gcc/testsuite/g++.dg/expr/for8.C 2025-02-04 21:55:01.460717178 +0100
@@ -0,0 +1,22 @@
+// PR c++/86769
+// { dg-do run }
+// { dg-options "-O1" }
+
+__attribute__((noipa)) void
+foo (int)
+{
+ static int a = 0;
+ if (++a == 3)
+ __builtin_abort ();
+}
+
+int
+main ()
+{
+ volatile int x = 10;
+ for (int l = 1; int d = x - l; l = d + 1)
+ {
+ int &z = d;
+ foo (z);
+ }
+}
--- gcc/testsuite/g++.dg/ext/stmtexpr27.C.jj 2025-02-04 21:55:01.460717178
+0100
+++ gcc/testsuite/g++.dg/ext/stmtexpr27.C 2025-02-04 21:55:01.460717178
+0100
@@ -0,0 +1,64 @@
+// PR c++/86769
+// { dg-do run }
+// { dg-options "" }
+
+struct A {
+ int a;
+ A (int x) : a(x) {}
+ ~A () {}
+ A (const A &x) : a(x.a) {}
+ operator bool () { return a != 0; }
+};
+
+int
+main ()
+{
+ int v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; j < ({ if (i == 1 && j == 1) continue; 4; }); ++j)
+ ++v;
+ if (v != 9)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; j < ({ if (i == 1 && j == 1) break; 4; }); ++j)
+ ++v;
+ if (v != 5)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; j < 4; ({ if (i == 1 && j == 1) continue; 1; }), ++j)
+ ++v;
+ if (v != 10)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; j < 4; ({ if (i == 1 && j == 1) break; 1; }), ++j)
+ ++v;
+ if (v != 6)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; A c = j < ({ if (i == 1 && j == 1) continue; 4; }); ++j)
+ ++v;
+ if (v != 9)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; A c = j < ({ if (i == 1 && j == 1) break; 4; }); ++j)
+ ++v;
+ if (v != 5)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; A c = j < 4; ({ if (i == 1 && j == 1) continue; 1; }), ++j)
+ ++v;
+ if (v != 10)
+ __builtin_abort ();
+ v = 0;
+ for (int i = 0; i < 3; ++i)
+ for (int j = 0; A c = j < 4; ({ if (i == 1 && j == 1) break; 1; }), ++j)
+ ++v;
+ if (v != 6)
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/cpp2a/constexpr-86769.C.jj 2025-02-04
21:55:01.460717178 +0100
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-86769.C 2025-02-04
21:55:01.460717178 +0100
@@ -0,0 +1,36 @@
+// PR c++/86769
+// { dg-do compile { target c++20 } }
+
+struct A {
+ int *a;
+ constexpr A (int x) : a (new int (x)) {}
+ constexpr A (const A &x) : a (new int (x.a[0])) {}
+ constexpr ~A () { delete a; }
+ constexpr operator bool () { return *a != 0; }
+};
+
+constexpr int
+foo ()
+{
+ int i = 0;
+ for (A a = 0; A b = a.a[0] < 16; a.a[0] += b.a[0])
+ i += a.a[0] + b.a[0];
+ return i;
+}
+
+static_assert (foo () == 136);
+
+constexpr int
+bar ()
+{
+ int i = 0;
+ A a = 0;
+ while (A b = a.a[0] < 15)
+ {
+ i += a.a[0] + b.a[0];
+ a.a[0] += b.a[0];
+ }
+ return i;
+}
+
+static_assert (bar () == 120);
--- gcc/testsuite/g++.dg/cpp26/name-independent-decl7.C.jj 2025-02-05
11:33:39.587617511 +0100
+++ gcc/testsuite/g++.dg/cpp26/name-independent-decl7.C 2025-02-05
11:42:32.978100179 +0100
@@ -0,0 +1,27 @@
+// P2169R4 - A nice placeholder with no name
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused-variable -Wunused-but-set-variable
-Wunused-parameter -Wshadow" }
+
+int bar ();
+
+void
+baz ()
+{
+ for (; int _ = bar (); ++_)
+ int _ = 1; // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ for (int _ = bar ();
+ int _ = bar (); ) // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ int _ = 2; // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ for (int _ = bar ();
+ int _ = bar (); ) // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ ;
+ for (; int _ = bar (); ++_)
+ {
+ int _ = 3; // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ }
+ for (int _ = bar ();
+ int _ = bar (); ) // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ {
+ int _ = 4; // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ }
+}
--- gcc/testsuite/g++.dg/cpp26/name-independent-decl8.C.jj 2025-02-05
11:38:24.814597185 +0100
+++ gcc/testsuite/g++.dg/cpp26/name-independent-decl8.C 2025-02-05
11:45:14.093830402 +0100
@@ -0,0 +1,24 @@
+// P2169R4 - A nice placeholder with no name
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+int bar ();
+
+void
+baz ()
+{
+ for (int _ = bar ();
+ int _ = bar (); ++_) // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ ; // { dg-error "reference to '_' is ambiguous"
"" { target *-*-* } .-1 }
+ for (; int _ = bar (); ++_)
+ {
+ int _ = 3; // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ ++_; // { dg-error "reference to '_' is ambiguous" }
+ }
+ for (int _ = bar ();
+ int _ = bar (); ) // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ {
+ int _ = 4; // { dg-warning "name-independent declarations
only available with" "" { target c++23_down } }
+ ++_; // { dg-error "reference to '_' is ambiguous" }
+ }
+}
Jakub
