WinMerge says two files are identical when doing a diff on the directory, but comparing the files shows differences

Question

I have two folders on my desktop, PreChanges and PostChanges.

PostChanges contains a few more files than PreChanges, but otherwise everything in one appears in the other.

If I use WinMerge to compare these two directories, including subfolders, it tells me only 4 documents are different. Here is a screenshot if it saying a particular file is Identicial:

But if I double click on it to diff that file specifically:

We can plainly see they are not identical.

What gives?

Answer 1

WinMerge has a number of options that affect how it compares files. They are listed under Edit > Options and under Tools > Filters.

Under Options you can for instance set set that WinMerge compares files only on size. So your change from 50 to 10 would then not be picked up.

Maybe one of these options is masking your diffs. WinMerge will report that the files are identical, according to the criteria set in Options. The file diffs will however be shown when you open the files in WinMerge.

Under Filters you can enter regular expressions for patterns to ignore.

Maybe some patterns are still in there; a result of previous compare operations.

Answer 2

What is your file encoding? WinMerge seems pretty buggy with Unicode - it could be this.

See:

• https://sourceforge.net/p/winmerge/bugs/1930/
• http://forums.winmerge.org/viewtopic.php?f=4&t=178

Here are some alternatives, which may also solve the problem!

• https://www.freefilesync.org/
• http://meldmerge.org/

(I'm not affiliated with these products in any way, but they come up often on developer lists)