Parse exception for RAW string template (Java 21+)

[diversit]

In Java 21/22, when using a String template with a raw String, checkstyle fails with a parsing error:

Maven checkstyle output:

An error has occurred in Checkstyle report generation.: Failed during checkstyle configuration: 
Exception was thrown while processing /path/to/a/java/Class.java: IllegalStateException occurred 
while parsing file /path/to/a/java/Class.java. 90:24: mismatched input '(' expecting ';': InputMismatchException

I have verified this issue by adding

   String result11 = STR."""
                Hello World
                """;

to the Checkstyle's com/puppycrawl/tools/checkstyle/grammar/java21/InputStringTemplateBasic.java test case.

See updated test case InputStringTemplateBasic.java

The test fails with
Java21AstRegressionTest.testBasicStringTemplate:42->AbstractTreeTestSupport.verifyAst:77->AbstractTreeTestSupport.verifyAst:57 » Checkstyle IllegalStateException occurred while parsing file /Users/dhl/Project/others/checkstyle/src/test/resources-noncompilable/com/puppycrawl/tools/checkstyle/grammar/java21/InputStringTemplateBasic.java

Using a raw string with a String Template is valid syntax. See Java 21 String Templates: Multiline String Templates and Java 22 String Templates: Multiline String Template

Also using StringTemplate.RAW, which is an alternative notation of STR."""..""" fails with a parse error.
Java Api Docs StringTemplate

import static java.lang.StringTemplate.RAW;

    // raw string
    String result11 = RAW."""
            Hello \{name}
            """;

Tested with:

Java: 21 and 22
Checkstyle: 10.14 and 10.15

[mahfouz72]

Checkstyle is currently unable to parse this syntax. there is an open issue for this #14195 (comment)
complete support for all java 21 new syntax (parsing and checkstyle checks) will be done by the summer.

[romani]

Also using StringTemplate.RAW, which is an alternative notation of STR.""".."""

@nrmancuso ,
Do we allow not STR ?

[nrmancuso]

Also using StringTemplate.RAW, which is an alternative notation of STR.""".."""

@nrmancuso , Do we allow not STR ?

This example is not valid syntax. Text blocks must begin with three quotes and a newline character.

I am removing the approved label since this is a duplicate of #14195

It is unlikely that we will ever support this syntax, since Java themselves have dropped it: #14805

I suggest that we close this issue and continue any discussion at #14195