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.
Tested powerpc64le-linux.
OK for trunk?
commit 26624b68aebd80d0c922ee48f944124dcc8c02e2
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Mon May 17 10:53:56 2021
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.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index f07e09a36d1..1e2d1d43184 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 00000000000..58412152238
--- /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
