From 5d93261bc03c9c6891ccd8c77ab22b2a09971905 Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Mon, 17 May 2021 10:53:56 +0100 Subject: [PATCH] c++: Fix diagnostic for binding lvalue reference to volatile rvalue [PR 100635] The current diagnostic assumes the reference binding fails because the reference is non-const, but it can also fail if the rvalue is volatile. Use the current diagnostic for non-const cases, and a modified diagnostic otherwise. gcc/cp/ChangeLog: PR c++/100635 * call.c (convert_like_internal): Print different diagnostic if the lvalue reference is const. gcc/testsuite/ChangeLog: * g++.dg/conversion/pr100635.C: New test. --- gcc/cp/call.c | 6 +++++- gcc/testsuite/g++.dg/conversion/pr100635.C | 12 ++++++++++++ 2 files changed, 17 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/conversion/pr100635.C diff --git a/gcc/cp/call.c b/gcc/cp/call.c index f07e09a..1e2d1d4 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -7900,9 +7900,13 @@ convert_like_internal (conversion *convs, tree expr, tree fn, int argnum, "type %qH to a value of type %qI", totype, next->type); } - else + else if (!CP_TYPE_CONST_P (TREE_TYPE (ref_type))) error_at (loc, "cannot bind non-const lvalue reference of " "type %qH to an rvalue of type %qI", totype, extype); + else // extype is volatile + error_at (loc, "cannot bind lvalue reference of type " + "%qH to an rvalue of type %qI", totype, + extype); } else if (!reference_compatible_p (TREE_TYPE (totype), extype)) { diff --git a/gcc/testsuite/g++.dg/conversion/pr100635.C b/gcc/testsuite/g++.dg/conversion/pr100635.C new file mode 100644 index 0000000..5841215 --- /dev/null +++ b/gcc/testsuite/g++.dg/conversion/pr100635.C @@ -0,0 +1,12 @@ +// PR c++/100635 +// { dg-do compile } +// { dg-additional-options "-Wno-volatile" { target c++2a } } + +struct S { }; +volatile S v(); +const volatile S& svol = v(); // { dg-error "cannot bind lvalue reference of type 'const volatile S&' to an rvalue of type 'volatile S'" } + +#if __cplusplus >= 201103L +volatile int&& declvol(); +const volatile int& voli = declvol(); // { dg-error "cannot bind lvalue reference of type 'const volatile int&' to an rvalue of type 'volatile int'" "" { target c++11} } +#endif -- 2.7.4