fix #2076

Parsers/PascalABCParserNewSaushkin/SemanticRules.cs

@@ -421,6 +421,7 @@ namespace GPPGParserScanner
                 if (!str.Value.Contains("{"))
                     return str;
                 string val = str.Value.Replace("{{","![&").Replace("}}}","}&]!").Replace("}}", "&]!");
+                
                 string[] arr = Regex.Split(val, @"\{[^\}]+\}");
                 Match match = Regex.Match(val, @"\{[^\}]+\}");
                 List<string> vars = new List<string>();
@@ -442,13 +443,18 @@ namespace GPPGParserScanner
                         var_formats.Add(ind, s.Substring(colon_pos));
                         s = s.Substring(0, colon_pos);
                         
-                    }  
+                    }
+                    if (s.IndexOf("&]!") != -1 || s.IndexOf("![&") != -1)
+                    {
+                        parsertools.errors.Add(new bad_format_string(parsertools.CurrentFileName, str.source_context, str));
+                        return str;
+                    }
                     vars.Add(s);
                     var_offsets.Add(match.Index);
                     match = match.NextMatch();
                     ind++;
                 }
-                if (vars.Count == 0)
+                if (vars.Count == 0 && val.IndexOf("![&") == -1 && val.IndexOf("{") != -1)
                 {
                     parsertools.errors.Add(new bad_format_string(parsertools.CurrentFileName, str.source_context, str));
                     return str;
@@ -457,6 +463,11 @@ namespace GPPGParserScanner
                 StringBuilder sb = new StringBuilder();
                 for (int i = 0; i < arr.Length; i++)
                 {
+                    if (arr[i].IndexOf("{") != -1 || arr[i].IndexOf("}") != -1)
+                    {
+                        parsertools.errors.Add(new bad_format_string(parsertools.CurrentFileName, str.source_context, str));
+                        return str;
+                    }
                     sb.Append(arr[i].Replace("![&", "{{").Replace("&]!", "}}"));
                     if (i < arr.Length - 1)
                     {

TestSuite/errors/err0335.pas

@@ -0,0 +1,3 @@
+begin
+  var s := $'{{1} {0}';
+end.

TestSuite/errors/err0336.pas

@@ -0,0 +1,3 @@
+begin
+  var s := $'{1}}';
+end.

TestSuite/errors/err0337.pas

@@ -0,0 +1,3 @@
+begin
+  var s := $'{1}} {0}';
+end.

TestSuite/formatstring7.pas

@@ -0,0 +1,9 @@
+begin
+  var s1 := $'{{0}} {1}';
+  assert(s1 = '{0} 1');
+  var s2 := $'';
+  var s3 := $'{{0}}';
+  assert(s3 = '{0}');
+  s3 := $'{{1 {0}';
+  assert(s3 = '{1 0');
+end.