137f2acad4
If the number of nested #if blocks exceeds 64, nest() increments the nesting depth and then reports an error. The message includes the line number for the start of the current #if block, which is read from past the end of the relevant array. Avoid the out-of-bounds read by reporting the error and exiting before the nesting depth has a chance to increase. Submitted by: Jonathan Nieder <jrnieder@gmail.com>