Don't capture characters around {}.
@@ -9,7 +9,7 @@ endif
syn region myrComment start=+/\*+ end=+\*/+
syn region myrComment start=+//+ end=+$+
syn match myrSpecial display contained "\\\(x\x\+\|\o\{1,3}\|u{[a-zA-Z0-9_]*}\|.\|$\)"
-syn match myrFormat display "[^{]{[^}]*}[^}]"
+syn match myrFormat display "{[^}]*}"
syn region myrString start=+"+ skip=+\\"+ end=+"+ contains=myrSpecial,myrFormat extend
syn region myrChar start=+'+ skip=+\\'+ end=+'+ contains=myrSpecial,myrFormat extend
syn keyword myrKeyword castto
