On Mon, May 05, 2025 at 02:14:39PM -0700, Junio C Hamano wrote: > Patrick Steinhardt <ps@xxxxxx> writes: > > > -M[<n>], --find-renames[=<n>] > > Detect renames. If <n> is specified, it is a threshold on the similarity index (i.e. amount > > of addition/deletions compared to the file’s size). For example, -M90% means Git should > > consider a delete/add pair to be a rename if more than 90% of the file hasn’t changed. > > Without a % sign, the number is to be read as a fraction, with a decimal point before it. > > I.e., -M5 becomes 0.5, and is thus the same as -M50%. Similarly, -M05 is the same as -M5%. > > To limit detection to exact renames, use -M100%. The default similarity index is 50%. > > > > What you probably wanted to say is `--find-renames=90%`, but without the > > percentage sign it is read as a fraction, where 1 means "exact copy" and > > 0 means "all different". > > I am confused. -M<number> without trailing %-sign is taken as > fraction against 1 followed by the same number of '0' has the > <number> has digits. -M5 is 5 over 10, -M50 is 50 over 100. -M90 > is 90 over 100, so -M90 and -M90% should mean the same thing. Hm, I guess _I_ was confused then. It doesn't feel natural to me that -M90 would mean 90% whereas -M5 means 50%, and the documentation isn't quite clear about this, either. > But you are right. When you want to claim your pre- and post- image > files still correspond with each other in a meaningful way, even > after making extensive change, you would want to _lower_, not raise, > your similarity threshold. If the default is -M50, then -M90 would > be a useful option to reject what Git (mistakenly) thinks are renames > and tell it to instead consider they are removals and creations. Yeah, at least that point stands :) Patrick
