Suppression comments for HHClientLinter don't mesh well with /**/ comments

[Lexidor Digital]

/* HHAST_FIXME[DontAwaitInALoop]
   Why I can't fix this now.
   HHAST_FIXME[5583]*/
    await ...;

The numbered FIXME must be on the literal preceding line. Fixmes for other linters such as DontAwaitInALoopLinter can live anywhere in the preceding comment.

I am expecting this to be a wontfix. I just had to bring it up to be sure.

[Yang, Bo]

The reason is that the HHClientLinter uses File::errorCodesToSuppress to determine the error codes suppressed, which is line based instead of range based, therefore only the marker in the previous line is considered.

hhast/src/File.hack

Lines 42 to 45 in 01f1e17

   public function errorCodesToSuppress(): shape( 
     'whole_file' => keyset<this::TErrorCode>, 
     'single_instance' => dict<this::TLineNumber, keyset<this::TErrorCode>>, 
   ) { 

To fix this issue, we can update the implementation of File::errorCodesToSuppress to let it actually parse the source file and produce range based suppression information.

I think this is doable, it just needs us to move the existing AST based linters suppression implementation into File::errorCodesToSuppress.

[Fred Emmott]

This behavior is shared with line based linters; there's a few solutions.

• Moving the AST-based solution into one and re-using it is one, but would also mean that these linters would need to construct an AST, find the node, and check trailing markup. That's another process call to hh_parse + the overhead of parsing the JSON and constructing the nodes. Might be worth it though
• The line-based suppression could be extended to understand multiline comments without a full AST, and treat it as if all suppressions were in the last line of the comment

[Lexidor Digital]

Something quite lazy and text based would probably do the trick.

if supp on line
  use supp
else if lastline contains "*/"
  scan until "/*" or until start of file
else if last line contains "//"
  scan while line contains "//"
else
  no supp