}
			return prevFrame
		}
		// If more helper PCs have been added since we last did the conversion
		if c.helperNames == nil {
			c.helperNames = make(map[string]struct{})
			for pc := range c.helperPCs {
				c.helperNames[pcToName(pc)] = struct{}{}
			}
		}
		if _, ok := c.helperNames[frame.Function]; !ok {
			// Found a frame that wasn't inside a helper function.
			return frame
		}
	}

	n := runtime.Callers(2, pc[:]) // skip runtime.Callers + Helper
	if n == 0 {
		panic("testing: zero callers found")
	}
	if _, found := f.helperPCs[pc[0]]; !found {
		f.helperPCs[pc[0]] = struct{}{}
		f.helperNames = nil // map will be recreated next time it is needed
	}
}

// Fail marks the function as having failed but continues execution.
func (f *F) Fail() {