When imlib2 encounters a pixmap that uses "\\" (which is actually "\" as per C spec) it segfaults. This can be seen in /usr/share/icons/notecase.xpm that comes in the notecase package in Extras. Both feh and epsilon crash when trying to process it. ImageMagick has no problem displaying it.
Not quite. ImageMagick has other problems displaying it. Gthumb, gqview, and netpbm-progs, too. They all parse and display the lines, which include \\, incorrectly. And actually, the original XPM documentation is not clear whether Standard C escaped character sequences can be used as pixel values, which are defined with a constant "characters per pixel" value. Theoretically, you could use \\\\ to get \\ in the compiled string and hence have four characters per pixel in the source file and two characters per pixel in the binary data. Very ugly for a file format that's supposed to be editable in a text-editor. Suggestion: Report it upstream for both "notecase" and "imlib2".
I've imported a fix for this but want to point out that the notecase.xpm is broken and ought to get fixed, too. Check this out: "[ c #8C928C", "\\ c #8C9274", "] c #848A6C", As you can see here in the colour table, the backslash escaped string has the same length than the non-escaped strings before and after it. The pixel values they want here are: "[ ", "\ " and "] ", i.e. two characters per pixel. Instead, the string with \\ expands to just '\', which is one character per pixel, missing a space after the backslash and before the tab. I'm not surprised that ordinary XPM parsers fail to handle such weird pixel values in addition to the \\ specialty.