Duplicate completion candidates for for_each & for collections

[radeksimko]

Currently we return two duplicate completion candidates when completing for_each under a dynamic block, in a block which also has the "standalone" for_each:

resource "aws_ec2_fleet" "name" {
  for_each = ["value"]
  dynamic "spot_options" {
    for_each = # HERE
  }
}

We should only provide one completion candidate.

[radeksimko]

This appears to be slightly more complicated than I originally expected.

Basically, the problem is that we first gather constraints and then do completion for each constraint individually.

Specifically for the mentioned example, the trigger is that for_each has multiple open constraints

hcl-lang/decoder/decoder.go

Lines 258 to 263 in 9f07ba7

	Expr: schema.ExprConstraints{
	schema.TraversalExpr{OfType: cty.Map(cty.DynamicPseudoType)},
	schema.TraversalExpr{OfType: cty.Set(cty.String)},
	schema.LiteralTypeExpr{Type: cty.Map(cty.DynamicPseudoType)},
	schema.LiteralTypeExpr{Type: cty.Set(cty.String)},
	},

and these are compared against the reference target of (also open) type cty.Dynamic results in the two duplicate matches.

hcl-lang/decoder/expression_candidates.go

Lines 19 to 41 in 9f07ba7

	constraints, editRng := constraintsAtPos(attr.Expr, ExprConstraints(schema.Expr), pos)
	candidates := lang.NewCandidates()
	candidates.IsComplete = true
	if len(schema.CompletionHooks) > 0 {
	candidates.IsComplete = false
	candidates.List = append(candidates.List, d.candidatesFromHooks(ctx, attr, schema, outerBodyRng, pos)...)
	}
	count := len(candidates.List)
	if len(constraints) > 0 && uint(count) < d.maxCandidates {
	prefixRng := editRng
	prefixRng.End = pos
	for _, cons := range constraints {
	if uint(count) >= d.maxCandidates {
	return candidates, nil
	}
	candidates.List = append(candidates.List, d.constraintToCandidates(ctx, cons, attr, outerBodyRng, prefixRng, editRng)...)
	count++
	}
	}

They both represent the same reference target (i.e. reference target collection works as expected), but first is a match against cty.Map(cty.DynamicPseudoType) and the second is a match against cty.Set(cty.String).