Fixed 'missing glyph doesn't use fontconfig config substitutions' bug

XftFontMatch does display-specific font configuration (commit 528241a).
Nice. Unfortunately, when we switched from FcFontMatch, we also stopped
storing the post-Fc{Config,Default}Substitute FcPattern for future
lookups. The result is that if a glyph isn't found in the primary font,
secondary font lookups use the original FcPattern, not the configured
one. If you have custom fontconfig rules (like me), this can be
disappointing.

I basically just copied the guts out of XftFontMatch[1] and saved
the intermediate configured FcPattern. Could be related to the bug that
inspired commit 4242027.

[1]: https://cgit.freedesktop.org/xorg/lib/libXft/tree/src/xftfont.c

1 files changed, 19 insertions, 3 deletions

diff --git a/st.c b/st.c
index e50e884..031272f 100644
--- a/st.c
+++ b/st.c
@@ -3373,16 +3373,32 @@ xgeommasktogravity(int mask)
 int
 xloadfont(Font *f, FcPattern *pattern)
 {
+        FcPattern *configured;
         FcPattern *match;
         FcResult result;
         XGlyphInfo extents;
         int wantattr, haveattr;
 
-        match = XftFontMatch(xw.dpy, xw.scr, pattern, &result);
-        if (!match)
+        /*
+         * Manually configure instead of calling XftMatchFont
+         * so that we can use the configured pattern for
+         * "missing glyph" lookups.
+         */
+        configured = FcPatternDuplicate(pattern);
+        if (!configured)
+                return 1;
+
+        FcConfigSubstitute(NULL, configured, FcMatchPattern);
+        XftDefaultSubstitute(xw.dpy, xw.scr, configured);
+
+        match = FcFontMatch(NULL, configured, &result);
+        if (!match) {
+                FcPatternDestroy(configured);
                 return 1;
+        }
 
         if (!(f->match = XftFontOpenPattern(xw.dpy, match))) {
+                FcPatternDestroy(configured);
                 FcPatternDestroy(match);
                 return 1;
         }
@@ -3414,7 +3430,7 @@ xloadfont(Font *f, FcPattern *pattern)
                 strlen(ascii_printable), &extents);
 
         f->set = NULL;
-        f->pattern = FcPatternDuplicate(pattern);
+        f->pattern = configured;
 
         f->ascent = f->match->ascent;
         f->descent = f->match->descent;