HCL Parser does not accept a comment as the last line in the file

[mccartney]

What is the smallest, simplest way to reproduce the problem?

    @Test
    void commentAsTheLastLine() {
        rewriteRun(
          hcl(
            """
              locals {
                a = 3
              }
              # Nice code, right?
            """
          )
        );
    }

What is the full stack trace of any errors you encountered?

[...]
Caused by: org.openrewrite.hcl.HclParsingException: Syntax error in file.tf at line 4:0 token recognition error at: '# Nice code, right?'.
	at org.openrewrite.hcl.HclParser$ForwardingErrorListener.syntaxError(HclParser.java:105)
	... 130 more
Caused by: LexerNoViableAltException('#')
	at org.antlr.v4.runtime.atn.LexerATNSimulator.failOrAccept(LexerATNSimulator.java:309)
	at org.antlr.v4.runtime.atn.LexerATNSimulator.execATN(LexerATNSimulator.java:230)
	at org.antlr.v4.runtime.atn.LexerATNSimulator.match(LexerATNSimulator.java:114)
	at org.antlr.v4.runtime.Lexer.nextToken(Lexer.java:141)
	... 127 more

[timtebeek]

hi @mccartney ; thanks for the report! This seems very similar to

• HCL Parser is confused with comment lines that contain // <comment> #4544

Let me see if the suggestion reported there also fixes this issue.

[timtebeek]

Sadly this needs work beyond what was done in #4616 ; Any help appreciated!

[rahul3509]

I can look into it. I have also seen similar issue. Will get some more details regarding this

[mccartney]

I suspect this has something to do with the \n at the end of this rule:

rewrite/rewrite-hcl/src/main/antlr/HCLLexer.g4

Line 54 in f6d17f4

LINE_COMMENT : ('//' | '#') ~[\r\n]* '\r'?'\n' -> channel(HIDDEN);

Other languages use NEWLINE or EOF:

rewrite/rewrite-json/src/main/antlr/JSON5.g4

Line 51 in aa59e6a

: '//' .*? (NEWLINE | EOF) -> skip

[rahul3509]

I was debugging the issue looks like

rewrite/rewrite-hcl/src/main/java/org/openrewrite/hcl/HclParser.java

Line 69 in f6d17f4

).visitConfigFile(parser.configFile());

visitConfigFile function call is failing, Looking into it.

[rahul3509]

I have tested the grammar is alright it is parsing and tokenizing contents of input properly.

[mccartney]

Related discussion in Antlr group: https://groups.google.com/g/antlr-discussion/c/1mJ0n38Jf8c?pli=1