Repost from squizlabs/PHP_CodeSniffer#3161 by @gsherwood:

The colon after a goto label does not have to be the very next token; there can be whitespace and comments between them. PHP_CodeSniffer will not tokenize the label correctly unless the colon immediately follows the label.

To fix this, T_GOTO_LABEL should be changed to include the label only, and exclude the colon.

So a: becomes:

T_GOTO_LABEL => a T_COLON => : 

Instead of:

T_GOTO_LABEL => a: 

---

And a /*comment here*/ : becomes:

T_GOTO_LABEL => a T_WHITESPACE => · T_COMMENT => /*comment·here*/ T_WHITESPACE => · T_COLON => : 

Instead of:

T_STRING => a T_WHITESPACE => · T_COMMENT => /*comment·here*/ T_WHITESPACE => · T_COLON => :