Add a rule for illegal empty braces.

Author: vpetrovykh

grammars/MagicPython.cson

@@ -870,6 +870,11 @@ repository:
       {
         include: "#string-line-continuation"
       }
+      {
+        comment: "empty braces are illegal"
+        name: "invalid.illegal.brace.python"
+        match: "({\\s*?})"
+      }
       {
         name: "constant.character.escape.python"
         match: "({{|}})"

grammars/MagicPython.tmLanguage

@@ -1406,6 +1406,14 @@
             <key>include</key>
             <string>#string-line-continuation</string>
           </dict>
+          <dict>
+            <key>comment</key>
+            <string>empty braces are illegal</string>
+            <key>name</key>
+            <string>invalid.illegal.brace.python</string>
+            <key>match</key>
+            <string>({\s*?})</string>
+          </dict>
           <dict>
             <key>name</key>
             <string>constant.character.escape.python</string>

grammars/src/MagicPython.syntax.yaml

@@ -615,11 +615,16 @@ repository:
       - include: '#escape-sequence-unicode'
       - include: '#escape-sequence'
       - include: '#string-line-continuation'
+      - comment: empty braces are illegal
+        name: invalid.illegal.brace.python
+        match: ({\s*?})
       - name: constant.character.escape.python
         match: ({{|}})
       - name: invalid.illegal.brace.python
         match: (}(?!}))
 
+
+
   fstring-illegal-single-brace:
     comment: it is illegal to have a multiline brace inside a single-line
              string

test/fstrings/empty1.py

@@ -0,0 +1,22 @@
+f"{} {  }"
+f"""{}
+{  }
+"""
+
+
+
+
+
+f             : source.python, storage.type.string.python, string.quoted.single.python
+"             : punctuation.definition.string.begin.python, source.python, string.quoted.single.python
+{}            : invalid.illegal.brace.python, source.python
+              : source.python, string.quoted.single.python
+{  }          : invalid.illegal.brace.python, source.python
+"             : punctuation.definition.string.end.python, source.python, string.quoted.single.python
+f             : source.python, storage.type.string.python, string.quoted.multi.python
+"""           : punctuation.definition.string.begin.python, source.python, string.quoted.multi.python
+{}            : invalid.illegal.brace.python, source.python
+              : source.python, string.quoted.multi.python
+{  }          : invalid.illegal.brace.python, source.python
+              : source.python, string.quoted.multi.python
+"""           : punctuation.definition.string.end.python, source.python, string.quoted.multi.python