From: Jason Merrill <jason@redhat.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++: Disallow jumps into statement expressions
Date: Mon, 3 Oct 2022 11:02:05 -0400 [thread overview]
Message-ID: <7c31e64f-5bf5-0369-f18d-5257fe277bcf@redhat.com> (raw)
In-Reply-To: <Yzl3afY3XTnM7sQ+@tucnak>
On 10/2/22 07:35, Jakub Jelinek wrote:
> On Fri, Sep 30, 2022 at 04:39:25PM -0400, Jason Merrill wrote:
>>> --- gcc/cp/decl.cc.jj 2022-09-22 00:14:55.478599363 +0200
>>> +++ gcc/cp/decl.cc 2022-09-22 00:24:01.121178256 +0200
>>> @@ -223,6 +223,7 @@ struct GTY((for_user)) named_label_entry
>>> bool in_transaction_scope;
>>> bool in_constexpr_if;
>>> bool in_consteval_if;
>>> + bool in_assume;
>>
>> I think it would be better to reject jumps into statement-expressions like
>> the C front-end.
>
> Ok, here is a self-contained patch that does that.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK, thanks.
> 2022-10-01 Jakub Jelinek <jakub@redhat.com>
>
> * cp-tree.h (BCS_STMT_EXPR): New enumerator.
> * name-lookup.h (enum scope_kind): Add sk_stmt_expr.
> * name-lookup.cc (begin_scope): Handle sk_stmt_expr like sk_block.
> * semantics.cc (begin_compound_stmt): For BCS_STMT_EXPR use
> sk_stmt_expr.
> * parser.cc (cp_parser_statement_expr): Use BCS_STMT_EXPR instead of
> BCS_NORMAL.
> * decl.cc (struct named_label_entry): Add in_stmt_expr.
> (poplevel_named_label_1): Handle sk_stmt_expr.
> (check_previous_goto_1): Diagnose entering of statement expression.
> (check_goto): Likewise.
>
> * g++.dg/ext/stmtexpr24.C: New test.
>
> --- gcc/cp/cp-tree.h.jj 2022-09-30 18:38:55.351607176 +0200
> +++ gcc/cp/cp-tree.h 2022-10-01 13:06:20.731720730 +0200
> @@ -7599,7 +7599,8 @@ enum {
> BCS_NO_SCOPE = 1,
> BCS_TRY_BLOCK = 2,
> BCS_FN_BODY = 4,
> - BCS_TRANSACTION = 8
> + BCS_TRANSACTION = 8,
> + BCS_STMT_EXPR = 16
> };
> extern tree begin_compound_stmt (unsigned int);
>
> --- gcc/cp/name-lookup.h.jj 2022-09-23 09:02:31.103668514 +0200
> +++ gcc/cp/name-lookup.h 2022-10-01 13:37:50.158404107 +0200
> @@ -200,6 +200,7 @@ enum scope_kind {
> init-statement. */
> sk_cond, /* The scope of the variable declared in the condition
> of an if or switch statement. */
> + sk_stmt_expr, /* GNU statement expression block. */
> sk_function_parms, /* The scope containing function parameters. */
> sk_class, /* The scope containing the members of a class. */
> sk_scoped_enum, /* The scope containing the enumerators of a C++11
> --- gcc/cp/name-lookup.cc.jj 2022-09-13 09:21:28.123540623 +0200
> +++ gcc/cp/name-lookup.cc 2022-10-01 13:37:26.383732959 +0200
> @@ -4296,6 +4296,7 @@ begin_scope (scope_kind kind, tree entit
> case sk_scoped_enum:
> case sk_transaction:
> case sk_omp:
> + case sk_stmt_expr:
> scope->keep = keep_next_level_flag;
> break;
>
> --- gcc/cp/semantics.cc.jj 2022-09-30 18:38:50.337675080 +0200
> +++ gcc/cp/semantics.cc 2022-10-01 13:09:34.958970367 +0200
> @@ -1761,6 +1761,8 @@ begin_compound_stmt (unsigned int flags)
> sk = sk_try;
> else if (flags & BCS_TRANSACTION)
> sk = sk_transaction;
> + else if (flags & BCS_STMT_EXPR)
> + sk = sk_stmt_expr;
> r = do_pushlevel (sk);
> }
>
> --- gcc/cp/parser.cc.jj 2022-09-30 18:38:55.374606864 +0200
> +++ gcc/cp/parser.cc 2022-10-01 13:08:27.367927479 +0200
> @@ -5272,7 +5272,7 @@ cp_parser_statement_expr (cp_parser *par
> /* Start the statement-expression. */
> tree expr = begin_stmt_expr ();
> /* Parse the compound-statement. */
> - cp_parser_compound_statement (parser, expr, BCS_NORMAL, false);
> + cp_parser_compound_statement (parser, expr, BCS_STMT_EXPR, false);
> /* Finish up. */
> expr = finish_stmt_expr (expr, false);
> /* Consume the ')'. */
> --- gcc/cp/decl.cc.jj 2022-09-27 08:27:47.671428567 +0200
> +++ gcc/cp/decl.cc 2022-10-01 13:14:57.990434730 +0200
> @@ -223,6 +223,7 @@ struct GTY((for_user)) named_label_entry
> bool in_transaction_scope;
> bool in_constexpr_if;
> bool in_consteval_if;
> + bool in_stmt_expr;
> };
>
> #define named_labels cp_function_chain->x_named_labels
> @@ -538,6 +539,9 @@ poplevel_named_label_1 (named_label_entr
> case sk_transaction:
> ent->in_transaction_scope = true;
> break;
> + case sk_stmt_expr:
> + ent->in_stmt_expr = true;
> + break;
> case sk_block:
> if (level_for_constexpr_if (bl->level_chain))
> ent->in_constexpr_if = true;
> @@ -3487,7 +3491,7 @@ check_previous_goto_1 (tree decl, cp_bin
> bool complained = false;
> int identified = 0;
> bool saw_eh = false, saw_omp = false, saw_tm = false, saw_cxif = false;
> - bool saw_ceif = false;
> + bool saw_ceif = false, saw_se = false;
>
> if (exited_omp)
> {
> @@ -3560,6 +3564,12 @@ check_previous_goto_1 (tree decl, cp_bin
> saw_tm = true;
> break;
>
> + case sk_stmt_expr:
> + if (!saw_se)
> + inf = G_(" enters statement expression");
> + saw_se = true;
> + break;
> +
> case sk_block:
> if (!saw_cxif && level_for_constexpr_if (b->level_chain))
> {
> @@ -3650,12 +3660,13 @@ check_goto (tree decl)
>
> if (ent->in_try_scope || ent->in_catch_scope || ent->in_transaction_scope
> || ent->in_constexpr_if || ent->in_consteval_if
> - || ent->in_omp_scope || !vec_safe_is_empty (ent->bad_decls))
> + || ent->in_omp_scope || ent->in_stmt_expr
> + || !vec_safe_is_empty (ent->bad_decls))
> {
> diagnostic_t diag_kind = DK_PERMERROR;
> if (ent->in_try_scope || ent->in_catch_scope || ent->in_constexpr_if
> || ent->in_consteval_if || ent->in_transaction_scope
> - || ent->in_omp_scope)
> + || ent->in_omp_scope || ent->in_stmt_expr)
> diag_kind = DK_ERROR;
> complained = identify_goto (decl, DECL_SOURCE_LOCATION (decl),
> &input_location, diag_kind);
> @@ -3703,6 +3714,8 @@ check_goto (tree decl)
> inform (input_location, " enters %<constexpr if%> statement");
> else if (ent->in_consteval_if)
> inform (input_location, " enters %<consteval if%> statement");
> + else if (ent->in_stmt_expr)
> + inform (input_location, " enters statement expression");
> }
>
> if (ent->in_omp_scope)
> --- gcc/testsuite/g++.dg/ext/stmtexpr24.C.jj 2022-10-01 13:34:01.471565458 +0200
> +++ gcc/testsuite/g++.dg/ext/stmtexpr24.C 2022-10-01 13:39:56.078662362 +0200
> @@ -0,0 +1,27 @@
> +// { dg-do compile }
> +// { dg-options "" }
> +
> +void
> +foo (int x)
> +{
> + bool a = false;
> + if (x == 1)
> + goto l1; // { dg-message "from here" }
> + a = ({ l0:; if (x == 0) goto l0; true; });
> + a = ({ if (x == 0) throw 1; true; });
> + a = ({ l1:; true; }); // { dg-error "jump to label 'l1'" }
> + // { dg-message "enters statement expression" "" { target *-*-* } .-1 }
> + a = ({ l2:; true; }); // { dg-error "jump to label 'l2'" }
> + switch (x)
> + {
> + case 2:
> + a = ({ case 3:; true; }); // { dg-error "jump to case label" }
> + // { dg-message "enters statement expression" "" { target *-*-* } .-1 }
> + a = ({ default:; true; }); // { dg-error "jump to case label" }
> + // { dg-message "enters statement expression" "" { target *-*-* } .-1 }
> + break;
> + }
> + if (x == 4)
> + goto l2; // { dg-message "from here" }
> + // { dg-message "enters statement expression" "" { target *-*-* } .-1 }
> +}
>
>
> Jakub
>
next prev parent reply other threads:[~2022-10-03 15:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 9:55 [PATCH] c++, c: Implement C++23 P1774R8 - Portable assumptions [PR106654] Jakub Jelinek
2022-09-30 20:39 ` Jason Merrill
2022-10-02 11:35 ` [PATCH] c++: Disallow jumps into statement expressions Jakub Jelinek
2022-10-03 15:02 ` Jason Merrill [this message]
2022-10-03 19:22 ` [PATCH] c++, c, v2: Implement C++23 P1774R8 - Portable assumptions [PR106654] Jakub Jelinek
2022-10-04 10:20 ` Jakub Jelinek
2022-10-04 20:42 ` Jason Merrill
2022-10-05 9:55 ` [PATCH] c++, c, v3: " Jakub Jelinek
2022-10-05 12:33 ` Jason Merrill
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