On 5/14/24 19:23, Andi Kleen wrote:
You need a template testcase; I expect it doesn't work in templates with the
current patch. It's probably enough to copy it in tsubst_expr where we
currently propagate CALL_EXPR_OPERATOR_SYNTAX.
I tried it with the appended test case, everything seems to work without
changes.
Does it cover the cases you were concerned about?
Not fully; this testcase doesn't seem to check for errors if tail-call
fails, only whether the syntax is accepted. So it would pass if the
attribute were simply ignored.
Okay I'm not clear how I would do that. Pattern match the assembler
in a target specific test case? From looking at the assembler output
everything got tail converted.
Write a testcase where the tail-call optimization can't happen, perhaps
because the caller and callee disagree on return type:
int f();
double h() { [[gnu::musttail]] return f(); } // error
template <class T>
T g() { [[gnu::musttail]] return f(); }
int main()
{
g<int>();
g<double>(); // should error, but doesn't with v6 patch set
}
Jason
