Fix f-string boundaries and add more tests

Author: nfnty

syntax/python.vim

@@ -264,7 +264,7 @@ if s:Enabled('g:python_highlight_string_format')
         syn match pythonStrFormat '{\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)\=\%(\.\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\[\%(\d\+\|[^!:\}]\+\)\]\)*\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=}' contained containedin=pythonString,pythonUniString,pythonUniRawString,pythonRawString
     else
         syn match pythonStrFormat "{\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)\=\%(\.\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\[\%(\d\+\|[^!:\}]\+\)\]\)*\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=}" contained containedin=pythonString,pythonRawString
-        syn region pythonStrInterpRegion matchgroup=pythonStrFormat start="\({\)\@<!{\({\)\@!"he=e,rs=e end="\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=\(}\)\@<!}\(}\)\@!"hs=s,re=s extend contained containedin=pythonFString,pythonRawFString contains=pythonStrInterpRegion,@pythonExpression
+        syn region pythonStrInterpRegion matchgroup=pythonStrFormat start="{" end="\%(![rsa]\)\=\%(:\%({\%(\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\%([^[:cntrl:][:punct:][:space:]]\|_\)*\|\d\+\)}\|\%([^}]\=[<>=^]\)\=[ +-]\=#\=0\=\d*,\=\%(\.\d\+\)\=[bcdeEfFgGnosxX%]\=\)\=\)\=}" extend contained containedin=pythonFString,pythonRawFString contains=pythonStrInterpRegion,@pythonExpression
         syn match pythonStrFormat "{{\|}}" contained containedin=pythonFString,pythonRawFString
     endif
 endif

tests/test.py

@@ -244,8 +244,11 @@ async def Test
 f"{var}...{arr[123]} normal {var['{'] // 0xff} \"xzcb\" 'xzcb' {var['}'] + 1} text"
 f"{expr1 if True or False else expr2} {None} wow {','.join(c.lower() for c in 'asdf')}"
 f"hello {expr:.2f} yes {(lambda: 0b1)():#03x} lol {var!r}"
-f'brackets: {{ 1 + 2 }} and {{{{ 3 + 4 }}}}'
+f'brackets: {{{ 1 + 2 }}} and {{{{ 3 + 4 }}}}'
 fr'this {that}'
+f"{f'{1+1}'}"
+'{{ }}'
+f"{"{test}"}"  # FIXME: syntax error that should not be highlighted
 
 # Doctests.