}
			if retOffset != lt.retOffset {
				t.Errorf("funcLayout(%v, %v).retOffset=%d, want %d", lt.typ, lt.rcvr, retOffset, lt.retOffset)
			}
			if !bytes.Equal(stack, lt.stack) {
				t.Errorf("funcLayout(%v, %v).stack=%v, want %v", lt.typ, lt.rcvr, stack, lt.stack)
			}
			if !bytes.Equal(gc, lt.gc) {
				t.Errorf("funcLayout(%v, %v).gc=%v, want %v", lt.typ, lt.rcvr, gc, lt.gc)
			}
			if !bytes.Equal(inRegs, lt.inRegs) {

	// clang says "unknown argument".
	// tcc says "unsupported"
	// AIX says "not recognized"
	// Older versions of GCC say "unrecognised debug output level".
	// For -fsplit-stack GCC says "'-fsplit-stack' is not supported".
	supported := !bytes.Contains(out, []byte("unrecognized")) &&
		!bytes.Contains(out, []byte("unknown")) &&
		!bytes.Contains(out, []byte("unrecognised")) &&

			// the mutex in freeConn here.
			println("double free of conn. conflicts are:\nA) " + getFreedFrom(dbConn{db, c}) + "\n\nand\nB) " + stack())
			panic("double free of conn.")
		}
		setFreedFrom(dbConn{db, c}, stack())
	}
}

// pollDuration is an arbitrary interval to wait between checks when polling for
// a condition to occur.
const pollDuration = 5 * time.Millisecond