Created attachment 496614 [details]
I lose some characters when using either media-libs/fontconfig 2.12.3-r1 or 2.12.4 with x11-terms/rxvt-unicode (See attached picture). media-libs/fontconfig-2.11.1-r2 works fine with x11-terms/rxvt-unicode 9.21 and 9.22-r1 (I didn't try 9.22).
The figure is with 'Noto Mono for Powerline', but regular 'Noto Mono', and 'Inconsolata' both show the same behavior.
First column of characters in figure (working) is with:
Second column of characters in figure (tofu) is with:
The list of characters showing as tofu is not exhaustive, they are simply the characters I use most often so I've noticed them.
Steps to reproduce:
1) Emerge the package >media-libs/fontconfig-2.11.1-r2 (no other packages are emerged/unmerged/re-emerged)
2) Open urxvt, see tofu characters.
3) Emerge the package =media-libs/fontconfig-2.11.1-r2 (no other packages are emerged/unmerged/re-emerged)
4) Open urxvt, see all expected characters.
Can you please try the latest unstable fontconfig and rxvt-unicode? Does it help?
I just tried fontconfig-2.12.6 with both rxvt-unicode-9.22 and 9.22-r1 with no luck. All characters show when using fontconfig-2.11-r2 with rxvt-unicode-9.21, 9.22, and 9.22-r1.
The problem here lies not with fontconfig or rxvt-unicode but with the fonts you use. At least as far as Inconsolata is concerned, the characters you have tried to use are simmply not there... I presume it used to work with older fontconfig because it somehow handled the font fallback for you.
The "solution" here is to have a fallback font configured for urxvt; The one I have seen mentioned most often in this context is Symbola but in principle any symbol/emoji font should work here. Then add something along the lines of
*font: xft:Inconsolata:size=12, xft:Symbola:size=8
to your URxvt configuration (scaling the symbol font down is necessary because rxvt-unicode does not render fallback characters whose width is larger
than the glyph box of the primary font).