From b10e031458d541f794dfaa08ba606487603a4bb6 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Wed, 5 Jan 2022 17:01:12 -0500 Subject: [PATCH] c++: destroy retval on throwing cleanup in try [PR33799] My earlier attempt to fix this bug didn't handle the case where both the return and the throwing cleanup are within a try-block that catches and discards the exception. Fixed by adding the retval cleanup to any try-blocks as well as the function body. PR102191 pointed out that we also weren't handling templates properly, so I moved the call out of the parser. PR c++/33799 PR c++/102191 gcc/cp/ChangeLog: * except.c (maybe_splice_retval_cleanup): Check current_binding_level. * semantics.c (do_poplevel): Call it here. * parser.c (cp_parser_compound_statement): Not here. gcc/testsuite/ChangeLog: * g++.dg/eh/return1.C: Add temporary in try block case. * g++.dg/cpp2a/constexpr-dtor11.C: New test. --- gcc/cp/except.c | 29 +++++++++----- gcc/cp/parser.c | 3 -- gcc/cp/semantics.c | 2 + gcc/testsuite/g++.dg/cpp2a/constexpr-dtor11.C | 12 ++++++ gcc/testsuite/g++.dg/eh/return1.C | 56 ++++++++++++++++++++++++--- 5 files changed, 84 insertions(+), 18 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/constexpr-dtor11.C diff --git a/gcc/cp/except.c b/gcc/cp/except.c index 5c7eeff..bcd9f84 100644 --- a/gcc/cp/except.c +++ b/gcc/cp/except.c @@ -1294,26 +1294,35 @@ maybe_set_retval_sentinel () current_retval_sentinel, boolean_true_node); } -/* COMPOUND_STMT is the STATEMENT_LIST for the current function body. If - current_retval_sentinel was set in this function, wrap the body in a - CLEANUP_STMT to destroy the return value on throw. */ +/* COMPOUND_STMT is the STATEMENT_LIST for some block. If COMPOUND_STMT is the + current function body or a try block, and current_retval_sentinel was set in + this function, wrap the block in a CLEANUP_STMT to destroy the return value + on throw. */ void maybe_splice_retval_cleanup (tree compound_stmt) { - /* If need_retval_cleanup set current_retval_sentinel, wrap the function body - in a CLEANUP_STMT to handle destroying the return value. */ - if (!DECL_CONSTRUCTOR_P (current_function_decl) + /* If we need a cleanup for the return value, add it in at the same level as + pushdecl_outermost_localscope. And also in try blocks. */ + bool function_body + = (current_binding_level->level_chain + && current_binding_level->level_chain->kind == sk_function_parms); + + if ((function_body || current_binding_level->kind == sk_try) + && !DECL_CONSTRUCTOR_P (current_function_decl) && !DECL_DESTRUCTOR_P (current_function_decl) && current_retval_sentinel) { location_t loc = DECL_SOURCE_LOCATION (current_function_decl); - - /* Add a DECL_EXPR for current_retval_sentinel. */ tree_stmt_iterator iter = tsi_start (compound_stmt); tree retval = DECL_RESULT (current_function_decl); - tree decl_expr = build_stmt (loc, DECL_EXPR, current_retval_sentinel); - tsi_link_before (&iter, decl_expr, TSI_SAME_STMT); + + if (function_body) + { + /* Add a DECL_EXPR for current_retval_sentinel. */ + tree decl_expr = build_stmt (loc, DECL_EXPR, current_retval_sentinel); + tsi_link_before (&iter, decl_expr, TSI_SAME_STMT); + } /* Skip past other decls, they can't contain a return. */ while (TREE_CODE (tsi_stmt (iter)) == DECL_EXPR) diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 6b91a0c..f40e707 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -12751,9 +12751,6 @@ cp_parser_compound_statement (cp_parser *parser, tree in_statement_expr, /* Parse an (optional) statement-seq. */ cp_parser_statement_seq_opt (parser, in_statement_expr); - if (function_body) - maybe_splice_retval_cleanup (compound_stmt); - /* Consume the `}'. */ braces.require_close (parser); diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 58f45e9..6456547 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -624,6 +624,8 @@ do_poplevel (tree stmt_list) { tree block = NULL; + maybe_splice_retval_cleanup (stmt_list); + if (stmts_are_full_exprs_p ()) block = poplevel (kept_level_p (), 1, 0); diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor11.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor11.C new file mode 100644 index 0000000..e371f89 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-dtor11.C @@ -0,0 +1,12 @@ +// PR c++/102191 +// { dg-do compile { target c++20 } } + +struct X { + struct A { + constexpr ~A() noexcept(false) { } + }; + + constexpr A operator()(auto...) { return {}; } +}; + +void f() { []() consteval { X{}(); }(); } diff --git a/gcc/testsuite/g++.dg/eh/return1.C b/gcc/testsuite/g++.dg/eh/return1.C index 5ef2f1de..ac22254 100644 --- a/gcc/testsuite/g++.dg/eh/return1.C +++ b/gcc/testsuite/g++.dg/eh/return1.C @@ -11,13 +11,16 @@ int c, d; #define THROWS #endif +extern "C" int printf (const char *, ...); +#define DEBUG // printf ("%p %s\n", this, __PRETTY_FUNCTION__) + struct X { - X(bool throws) : throws_(throws) { ++c; } - X(const X& x) : throws_(x.throws_) { ++c; } + X(bool throws) : throws_(throws) { ++c; DEBUG; } + X(const X& x); // not defined ~X() THROWS { - ++d; + ++d; DEBUG; if (throws_) { throw 1; } } private: @@ -42,6 +45,40 @@ void h() #endif } +X i() +{ + try { + X x(true); + return X(false); + } catch(...) {} + return X(false); +} + +X j() +{ + try { + return X(true),X(false); + } catch(...) {} + return X(false); +} + +template +T k() +{ + try { + return T(true),T(false); + } catch (...) {} + return T(true),T(false); +} + +X l() try { return X(true),X(false); } + catch (...) { return X(true),X(false); } + +template +T m() + try { return T(true),T(false); } + catch (...) { return T(true),T(false); } + int main() { try { f(); } @@ -53,6 +90,15 @@ int main() try { h(); } catch (...) {} - if (c != d) - throw; + try { i(); } + catch (...) {} + + try { j(); } catch (...) {} + + try { k(); } catch (...) {} + + try { l(); } catch (...) {} + try { m(); } catch (...) {} + + return c - d; } -- 2.7.4