We never called mark_use for a return value in a function with dependent
return type. In that situation we don't know if the use is as an rvalue or
lvalue, but we can use mark_exp_read instead.
gcc/cp/ChangeLog:
PR c++/96311
* typeck.c (check_return_expr): Call mark_exp_read in dependent
case.
gcc/testsuite/ChangeLog:
PR c++/96311
* g++.dg/cpp1y/lambda-generic-Wunused.C: New test.
dependent:
/* We should not have changed the return value. */
gcc_assert (retval == saved_retval);
+ /* We don't know if this is an lvalue or rvalue use, but
+ either way we can mark it as read. */
+ mark_exp_read (retval);
return retval;
}
--- /dev/null
+// PR c++/96311
+// { dg-do compile { target c++14 } }
+// { dg-additional-options -Wunused }
+
+auto foo()
+{
+ constexpr int used = 0;
+ return
+ [](auto unused)
+ {
+ return used;
+ };
+}
+
+int main()
+{
+ foo()(42);
+}