Fix issue with self in lexer

Author: C4tWithShell

community-rust-frontend/src/main/java/org/sonar/rust/RustGrammar.java

@@ -1852,7 +1852,8 @@ public static void lexicalpath(LexerlessGrammarBuilder b) {
       b.zeroOrMore(b.sequence(SPC, RustPunctuator.PATHSEP, SPC, SIMPLE_PATH_SEGMENT)));
     b.rule(SIMPLE_PATH_SEGMENT).is(b.firstOf(
       b.sequence(RustKeyword.KW_SUPER, b.nextNot(IDENTIFIER)),
-      RustKeyword.KW_SELF_VALUE, b.regexp("^crate$"), b.regexp(DOLLAR_CRATE_REGEX), IDENTIFIER));
+      b.sequence(RustKeyword.KW_SELF_VALUE, b.nextNot(b.regexp("[a-zA-Z0-9_]"))),
+      b.regexp("^crate$"), b.regexp(DOLLAR_CRATE_REGEX), IDENTIFIER));
 
     b.rule(PATH_IN_EXPRESSION).is(
       b.optional(SPC, RustPunctuator.PATHSEP, SPC),

community-rust-frontend/src/test/java/org/sonar/rust/RustLexerTest.java

@@ -87,4 +87,23 @@ void testParsing() {
     System.out.println(AstXmlPrinter.print(astNode));
 
   }
+
+  @Test
+  void testSelfInsideImportTokens() {
+      testImportParsing("selfish");
+      testImportParsing("self_api");
+  }
+
+  private void testImportParsing(String filename) {
+    String sexpr = "\n" +
+        "use api::" + filename + "::MyService; \n" +
+        "       fn update_rates(){" +
+        "             todo!()\n" +
+        "             }";
+
+    ParserAdapter<LexerlessGrammar> parser = new ParserAdapter<>(
+        StandardCharsets.UTF_8, RustGrammar.create().build());
+    
+    parser.parse(sexpr);
+  }
 }