This should fix Japanese fonts not working

src/os/unix/font_unix.cpp

@@ -109,7 +109,8 @@ bool SetFallbackFont(FontCacheSettings *settings, const char *language_isocode,
 	if (split != nullptr) *split = '\0';
 
 	/* First create a pattern to match the wanted language. */
-	FcPattern *pat = FcNameParse((FcChar8 *)lang);
+	//FcPattern *pat = FcNameParse((FcChar8*)lang);
+	FcPattern *pat = FcPatternCreate();
 	/* We only want to know the filename. */
 	FcObjectSet *os = FcObjectSetBuild(FC_FILE, FC_SPACING, FC_SLANT, FC_WEIGHT, nullptr);
 	/* Get the list of filenames matching the wanted language. */
@@ -122,6 +123,7 @@ bool SetFallbackFont(FontCacheSettings *settings, const char *language_isocode,
 	if (fs != nullptr) {
 		int best_weight = -1;
 		const char *best_font = nullptr;
+		int best_missing_glypths = 65536;
 
 		for (int i = 0; i < fs->nfont; i++) {
 			FcPattern *font = fs->fonts[i];
@@ -131,28 +133,31 @@ bool SetFallbackFont(FontCacheSettings *settings, const char *language_isocode,
 			if (res != FcResultMatch || file == nullptr) {
 				continue;
 			}
+			int missing = 0;
 
 			/* Get a font with the right spacing .*/
 			int value = 0;
 			FcPatternGetInteger(font, FC_SPACING, 0, &value);
-			if (callback->Monospace() != (value == FC_MONO) && value != FC_DUAL) continue;
+			if (callback->Monospace() != (value == FC_MONO) && value != FC_DUAL) missing += 1;
 
 			/* Do not use those that explicitly say they're slanted. */
 			FcPatternGetInteger(font, FC_SLANT, 0, &value);
-			if (value != 0) continue;
+			if (value != 0) missing += 1;
 
 			/* We want the fatter font as they look better at small sizes. */
 			FcPatternGetInteger(font, FC_WEIGHT, 0, &value);
-			if (value <= best_weight) continue;
+			if (value <= best_weight) missing += 1;
 
 			callback->SetFontNames(settings, (const char *)file);
 
-			bool missing = callback->FindMissingGlyphs();
-			Debug(fontcache, 1, "Font \"{}\" misses{} glyphs", file, missing ? "" : " no");
+			missing += callback->FindMissingGlyphs();
+			Debug(fontcache, 1, "Font \"{}\" misses {} glyphs for lang {}", file, missing, lang);
 
-			if (!missing) {
+			if (missing < best_missing_glypths) {
 				best_weight = value;
 				best_font = (const char *)file;
+				best_missing_glypths = missing;
+				if (missing == 0) break;
 			}
 		}
 
@@ -160,6 +165,7 @@ bool SetFallbackFont(FontCacheSettings *settings, const char *language_isocode,
 			ret = true;
 			callback->SetFontNames(settings, best_font);
 			InitFontCache(callback->Monospace());
+			Debug(fontcache, 1, "Selected font {} for lang {}", best_font, lang);
 		}
 
 		/* Clean up the list of filenames. */

src/strings.cpp

@@ -2035,7 +2035,7 @@ const char *GetCurrentLanguageIsoCode()
  * Check whether there are glyphs missing in the current language.
  * @return If glyphs are missing, return \c true, else return \c false.
  */
-bool MissingGlyphSearcher::FindMissingGlyphs()
+int MissingGlyphSearcher::FindMissingGlyphs()
 {
 	InitFontCache(this->Monospace());
 	const Sprite *question_mark[FS_END];
@@ -2045,6 +2045,7 @@ bool MissingGlyphSearcher::FindMissingGlyphs()
 	}
 
 	this->Reset();
+	int missing = 0;
 	for (const char *text = this->NextString(); text != nullptr; text = this->NextString()) {
 		FontSize size = this->DefaultSize();
 		for (WChar c = Utf8Consume(&text); c != '\0'; c = Utf8Consume(&text)) {
@@ -2063,11 +2064,11 @@ bool MissingGlyphSearcher::FindMissingGlyphs()
 				}
 
 				Debug(fontcache, 0, "Font is missing glyphs to display char 0x{:X} in {} font size", (int)c, size_name);
-				return true;
+				missing++;
 			}
 		}
 	}
-	return false;
+	return missing;
 }
 
 /** Helper for searching through the language pack. */
@@ -2142,7 +2143,7 @@ void CheckForMissingGlyphs(bool base_font, MissingGlyphSearcher *searcher)
 	if (bad_font) {
 		/* We found an unprintable character... lets try whether we can find
 		 * a fallback font that can print the characters in the current language. */
-		bool any_font_configured = !_fcsettings.medium.font.empty();
+		//bool any_font_configured = !_fcsettings.medium.font.empty();
 		FontCacheSettings backup = _fcsettings;
 
 		_fcsettings.mono.os_handle = nullptr;
@@ -2152,17 +2153,19 @@ void CheckForMissingGlyphs(bool base_font, MissingGlyphSearcher *searcher)
 
 		_fcsettings = backup;
 
-		if (!bad_font && any_font_configured) {
-			/* If the user configured a bad font, and we found a better one,
-			 * show that we loaded the better font instead of the configured one.
-			 * The colour 'character' might change in the
+		if (!bad_font) {
+			/* Show that we loaded fallback font. To do this properly we have
+			 * to set the colour of the string, otherwise we end up with a lot
+			 * of artifacts.* The colour 'character' might change in the
 			 * future, so for safety we just Utf8 Encode it into the string,
 			 * which takes exactly three characters, so it replaces the "XXX"
 			 * with the colour marker. */
+#if !defined(__ANDROID__) && !defined(__EMSCRIPTEN__)
 			static char *err_str = stredup("XXXThe current font is missing some of the characters used in the texts for this language. Using system fallback font instead.");
 			Utf8Encode(err_str, SCC_YELLOW);
 			SetDParamStr(0, err_str);
 			ShowErrorMessage(STR_JUST_RAW_STRING, INVALID_STRING_ID, WL_WARNING);
+#endif
 		}
 
 		if (bad_font && base_font) {

src/strings_func.h

@@ -276,7 +276,7 @@ public:
 	 */
 	virtual void SetFontNames(struct FontCacheSettings *settings, const char *font_name, const void *os_data = nullptr) = 0;
 
-	bool FindMissingGlyphs();
+	int FindMissingGlyphs();
 };
 
 void CheckForMissingGlyphs(bool base_font = true, MissingGlyphSearcher *search = nullptr);