From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1734) id 202593858D28; Fri, 3 Dec 2021 19:00:36 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 202593858D28 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Marek Polacek To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-5778] c++: Fix for decltype(auto) and parenthesized expr [PR103403] X-Act-Checkin: gcc X-Git-Author: Marek Polacek X-Git-Refname: refs/heads/trunk X-Git-Oldrev: 654cd743c88a28fb292f7c2cf5f4b10e4047e7d9 X-Git-Newrev: abd7712f91c99690f8b0046ea168b2782afbac69 Message-Id: <20211203190036.202593858D28@sourceware.org> Date: Fri, 3 Dec 2021 19:00:36 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 Dec 2021 19:00:36 -0000 https://gcc.gnu.org/g:abd7712f91c99690f8b0046ea168b2782afbac69 commit r12-5778-gabd7712f91c99690f8b0046ea168b2782afbac69 Author: Marek Polacek Date: Tue Nov 30 21:07:25 2021 -0500 c++: Fix for decltype(auto) and parenthesized expr [PR103403] In r11-4758, I tried to fix this problem: int &&i = 0; decltype(auto) j = i; // should behave like int &&j = i; error wherein do_auto_deduction was getting confused with a REFERENCE_REF_P and it didn't realize its operand was a name, not an expression, and deduced the wrong type. Unfortunately that fix broke this: int&& r = 1; decltype(auto) rr = (r); where 'rr' should be 'int &' since '(r)' is an expression, not a name. But because I stripped the INDIRECT_REF with the r11-4758 change, we deduced 'rr's type as if decltype had gotten a name, resulting in 'int &&'. I suspect I thought that the REF_PARENTHESIZED_P check when setting 'bool id' in do_auto_deduction would handle the (r) case, but that's not the case; while the documentation for REF_PARENTHESIZED_P specifically says it can be set in INDIRECT_REF, we don't actually do so. This patch sets REF_PARENTHESIZED_P even on REFERENCE_REF_P, so that do_auto_deduction can use it. It also removes code in maybe_undo_parenthesized_ref that I think is dead -- and we don't hit it while running dg.exp. To adduce more data, it also looks dead here: https://splichal.eu/lcov/gcc/cp/semantics.c.gcov.html (It's dead since r9-1417.) Also add a fixed test for c++/81176. PR c++/103403 gcc/cp/ChangeLog: * cp-gimplify.c (cp_fold): Don't recurse if maybe_undo_parenthesized_ref doesn't change its argument. * pt.c (do_auto_deduction): Don't strip REFERENCE_REF_P trees if they are REF_PARENTHESIZED_P. Use stripped_init when checking for id-expression. * semantics.c (force_paren_expr): Set REF_PARENTHESIZED_P on REFERENCE_REF_P trees too. (maybe_undo_parenthesized_ref): Remove dead code. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/decltype-auto2.C: New test. * g++.dg/cpp1y/decltype-auto3.C: New test. * g++.dg/cpp1y/decltype-auto4.C: New test. * g++.dg/cpp1z/decomp-decltype1.C: New test. Diff: --- gcc/cp/cp-gimplify.c | 3 +- gcc/cp/pt.c | 15 ++++--- gcc/cp/semantics.c | 18 ++------ gcc/testsuite/g++.dg/cpp1y/decltype-auto2.C | 12 +++++ gcc/testsuite/g++.dg/cpp1y/decltype-auto3.C | 12 +++++ gcc/testsuite/g++.dg/cpp1y/decltype-auto4.C | 65 +++++++++++++++++++++++++++ gcc/testsuite/g++.dg/cpp1z/decomp-decltype1.C | 28 ++++++++++++ 7 files changed, 133 insertions(+), 20 deletions(-) diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c index 0a002db14e7..e3ede02a48e 100644 --- a/gcc/cp/cp-gimplify.c +++ b/gcc/cp/cp-gimplify.c @@ -2421,7 +2421,8 @@ cp_fold (tree x) if (REF_PARENTHESIZED_P (x)) { tree p = maybe_undo_parenthesized_ref (x); - return cp_fold (p); + if (p != x) + return cp_fold (p); } goto unary; diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 6b560952639..d3efc6ea238 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -29889,13 +29889,18 @@ do_auto_deduction (tree type, tree init, tree auto_node, } else if (AUTO_IS_DECLTYPE (auto_node)) { + /* Figure out if INIT is an unparenthesized id-expression or an + unparenthesized class member access. */ tree stripped_init = tree_strip_any_location_wrapper (init); - if (REFERENCE_REF_P (stripped_init)) + /* We need to be able to tell '(r)' and 'r' apart (when it's of + reference type). Only the latter is an id-expression. */ + if (REFERENCE_REF_P (stripped_init) + && !REF_PARENTHESIZED_P (stripped_init)) stripped_init = TREE_OPERAND (stripped_init, 0); - bool id = (DECL_P (stripped_init) - || ((TREE_CODE (init) == COMPONENT_REF - || TREE_CODE (init) == SCOPE_REF) - && !REF_PARENTHESIZED_P (init))); + const bool id = (DECL_P (stripped_init) + || ((TREE_CODE (stripped_init) == COMPONENT_REF + || TREE_CODE (stripped_init) == SCOPE_REF) + && !REF_PARENTHESIZED_P (stripped_init))); tree deduced = finish_decltype_type (init, id, complain); deduced = canonicalize_type_argument (deduced, complain); if (deduced == error_mark_node) diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index cd1956497f8..edba4b60e10 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -2049,7 +2049,8 @@ force_paren_expr (tree expr, bool even_uneval) return expr; if (TREE_CODE (expr) == COMPONENT_REF - || TREE_CODE (expr) == SCOPE_REF) + || TREE_CODE (expr) == SCOPE_REF + || REFERENCE_REF_P (expr)) REF_PARENTHESIZED_P (expr) = true; else if (DECL_P (tree_strip_any_location_wrapper (expr))) { @@ -2072,19 +2073,8 @@ maybe_undo_parenthesized_ref (tree t) if (cxx_dialect < cxx14) return t; - if (INDIRECT_REF_P (t) && REF_PARENTHESIZED_P (t)) - { - t = TREE_OPERAND (t, 0); - while (TREE_CODE (t) == NON_LVALUE_EXPR - || TREE_CODE (t) == NOP_EXPR) - t = TREE_OPERAND (t, 0); - - gcc_assert (TREE_CODE (t) == ADDR_EXPR - || TREE_CODE (t) == STATIC_CAST_EXPR); - t = TREE_OPERAND (t, 0); - } - else if ((TREE_CODE (t) == PAREN_EXPR || TREE_CODE (t) == VIEW_CONVERT_EXPR) - && REF_PARENTHESIZED_P (t)) + if ((TREE_CODE (t) == PAREN_EXPR || TREE_CODE (t) == VIEW_CONVERT_EXPR) + && REF_PARENTHESIZED_P (t)) t = TREE_OPERAND (t, 0); return t; diff --git a/gcc/testsuite/g++.dg/cpp1y/decltype-auto2.C b/gcc/testsuite/g++.dg/cpp1y/decltype-auto2.C new file mode 100644 index 00000000000..56e011e36f4 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/decltype-auto2.C @@ -0,0 +1,12 @@ +// PR c++/103403 +// { dg-do compile { target c++14 } } + +template +auto constexpr RtoL1(T&& r) -> decltype(auto) { + return (r); +}; +int main() { + int t; + int x{3}; + decltype (RtoL1(x+0)) y = t; +} diff --git a/gcc/testsuite/g++.dg/cpp1y/decltype-auto3.C b/gcc/testsuite/g++.dg/cpp1y/decltype-auto3.C new file mode 100644 index 00000000000..914e87f5b79 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/decltype-auto3.C @@ -0,0 +1,12 @@ +// PR c++/103403 +// { dg-do compile { target c++14 } } + +int main() +{ + int i = 1; + int&& r = 1; + + decltype(auto) ri = (i); + decltype(auto) rr = (r); + decltype((r)) rr2 = (r); +} diff --git a/gcc/testsuite/g++.dg/cpp1y/decltype-auto4.C b/gcc/testsuite/g++.dg/cpp1y/decltype-auto4.C new file mode 100644 index 00000000000..9765857efb1 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/decltype-auto4.C @@ -0,0 +1,65 @@ +// PR c++/103403 +// { dg-do compile { target c++14 } } + +struct false_type { static constexpr bool value = false; }; +struct true_type { static constexpr bool value = true; }; +template +struct is_same : false_type {}; +template +struct is_same : true_type {}; + +int fn (); +int &ref (); +int &&rref (); + +struct S { + int i; + int &r = i; +}; + +void +ids () +{ + const S *s = new S(); + int i; + int &ir = i; + decltype(auto) r1 = s->i; + static_assert (is_same::value, ""); + decltype(auto) r2 = s->r; + static_assert (is_same::value, ""); + decltype(auto) r3 = i; + static_assert (is_same::value, ""); + decltype(auto) r4 = ir; + static_assert (is_same::value, ""); +} + +void +nonids () +{ + const S *s = new S(); + int i; + int &ir = i; + int &&irr = 42; + decltype(auto) r1 = fn (); + static_assert (is_same::value, ""); + decltype(auto) r2 = (fn ()); + static_assert (is_same::value, ""); + decltype(auto) r3 = ref (); + static_assert (is_same::value, ""); + decltype(auto) r4 = (ref ()); + static_assert (is_same::value, ""); + decltype(auto) r5 = rref (); + static_assert (is_same::value, ""); + decltype(auto) r6 = (rref ()); + static_assert (is_same::value, ""); + decltype(auto) r8 = (s->i); + static_assert (is_same::value, ""); + decltype(auto) r9 = (s->r); + static_assert (is_same::value, ""); + decltype(auto) r10 = (i); + static_assert (is_same::value, ""); + decltype(auto) r11 = (ir); + static_assert (is_same::value, ""); + decltype(auto) r12 = (irr); + static_assert (is_same::value, ""); +} diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp-decltype1.C b/gcc/testsuite/g++.dg/cpp1z/decomp-decltype1.C new file mode 100644 index 00000000000..e8ca0fc0bee --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/decomp-decltype1.C @@ -0,0 +1,28 @@ +// PR c++/81176 +// { dg-do compile { target c++17 } } + +namespace std { + template struct tuple_size; + template struct tuple_element; +} + +struct A { + int i; + template int& get() { return i; } +}; + +template<> struct std::tuple_size { static const int value = 2; }; +template struct std::tuple_element { using type = int; }; + +template struct same_type; +template struct same_type {}; + +void +foo (A x) +{ + auto [ a, b ] = x; + decltype(auto) c = a; + same_type{}; + same_type{}; +} +