`SynLongIdent.IdentsWithTrivia` throws exceptions

[auduchinok]

module Module

A.

Ast. Trying to get the idents with trivia leads to the following exception:

Message = “difference between idents and trivia”

StackTraceString = “
  at FSharp.Compiler.Syntax.SynLongIdent.get_IdentsWithTrivia()
    in C:\Developer\fsharp-rebase\src\Compiler\SyntaxTree\SyntaxTree.fs:line 51
 at JetBrains.ReSharper.Plugins.FSharp.Psi.LanguageService.Parsing.FSharpExpressionTreeBuilder.ProcessLongIdentifierExpression(SynLongIdent lidWithDots, Range range)
    in C:\Developer\resharper-fsharp\ReSharper.FSharp\src\FSharp.Psi.Features\src\Parsing\FSharpImplTreeBuilder.fs:line 1188

I can make a workaround, but it's suspicious that the trivia is missing (i.e. empty list instead of [None]), and it should't probably throw instead of return None in this case.

cc @nojaf

[nojaf]

Any idea in the grammar where it is creating A.?
I feel like the problem is more over there that it created ident A without adding the trivia.

and it should't probably throw instead of return None in this case.

Debatable, I don't have any strong sentiment about that part.

[auduchinok]

Any idea in the grammar where it is creating A.?

It looks like it could be this:

fsharp/src/Compiler/SyntaxTree/SyntaxTreeOps.fs

Lines 466 to 471 in bdb6462

	let mkSynDotMissing mDot m l =
	match l with
	| SynExpr.LongIdent (isOpt, SynLongIdent (lid, dots, trivia), None, _) ->
	// REVIEW: MEMORY PERFORMANCE: This list operation is memory intensive (we create a lot of these list nodes)
	SynExpr.LongIdent(isOpt, SynLongIdent(lid, dots @ [ mDot ], trivia), None, m)
	| SynExpr.Ident id -> SynExpr.LongIdent(false, SynLongIdent([ id ], [ mDot ], []), None, m)

Debatable, I don't have any strong sentiment about that part.

With this exception this API is just too dangerous to use, as it throws on unfinished code during normal typing (I had to remove all its usages for now). Adding None for missing trivia items would make it much safer.

[dsyme]

@vzarytovskii Sorry was it incorrect to merge to main at the moment?