Merge pull request #692 from hashicorp/support-incomplete-references-in-object-items

feat: return an `ExprSyntaxError` for invalid references that end in a dot

Author: ansgarm

hclsyntax/parser.go

@@ -811,9 +811,16 @@ Traversal:
 				// will probably be misparsed until we hit something that
 				// allows us to re-sync.
 				//
-				// We will probably need to do something better here eventually
-				// in order to support autocomplete triggered by typing a
-				// period.
+				// Returning an ExprSyntaxError allows us to pass more information
+				// about the invalid expression to the caller, which can then
+				// use this for example for completions that happen after typing
+				// a dot in an editor.
+				ret = &ExprSyntaxError{
+					Placeholder: cty.DynamicVal,
+					ParseDiags:  diags,
+					SrcRange:    hcl.RangeBetween(from.Range(), dot.Range),
+				}
+
 				p.setRecovery()
 			}
 
@@ -1516,6 +1523,16 @@ func (p *parser) parseObjectCons() (Expression, hcl.Diagnostics) {
 		diags = append(diags, valueDiags...)
 
 		if p.recovery && valueDiags.HasErrors() {
+			// If the value is an ExprSyntaxError, we can add an item with it, even though we will recover afterwards
+			// This allows downstream consumers to still retrieve this first invalid item, even though following items
+			// won't be parsed. This is useful for supplying completions.
+			if exprSyntaxError, ok := value.(*ExprSyntaxError); ok {
+				items = append(items, ObjectConsItem{
+					KeyExpr:   key,
+					ValueExpr: exprSyntaxError,
+				})
+			}
+
 			// If expression parsing failed then we are probably in a strange
 			// place in the token stream, so we'll bail out and try to reset
 			// to after our closing brace to allow parsing to continue.

hclsyntax/parser_test.go

@@ -2672,6 +2672,87 @@ block "valid" {}
 				},
 			},
 		},
+		{
+			"a = { b = c. }",
+			1,
+			&Body{
+				Attributes: Attributes{
+					"a": {
+						Name: "a",
+						Expr: &ObjectConsExpr{
+							Items: []ObjectConsItem{
+								{
+									KeyExpr: &ObjectConsKeyExpr{
+										Wrapped: &ScopeTraversalExpr{
+											Traversal: hcl.Traversal{
+												hcl.TraverseRoot{
+													Name: "b",
+													SrcRange: hcl.Range{
+														Start: hcl.Pos{Line: 1, Column: 7, Byte: 6},
+														End:   hcl.Pos{Line: 1, Column: 8, Byte: 7},
+													},
+												},
+											},
+											SrcRange: hcl.Range{
+												Start: hcl.Pos{Line: 1, Column: 7, Byte: 6},
+												End:   hcl.Pos{Line: 1, Column: 8, Byte: 7},
+											},
+										},
+									},
+									ValueExpr: &ExprSyntaxError{
+										Placeholder: cty.DynamicVal,
+										SrcRange: hcl.Range{
+											Start: hcl.Pos{Line: 1, Column: 11, Byte: 10},
+											End:   hcl.Pos{Line: 1, Column: 13, Byte: 12},
+										},
+										ParseDiags: hcl.Diagnostics{
+											{
+												Severity: hcl.DiagError,
+												Summary:  "Invalid attribute name",
+												Detail:   "An attribute name is required after a dot.",
+												Subject: &hcl.Range{
+													Start: hcl.Pos{Line: 1, Column: 14, Byte: 13},
+													End:   hcl.Pos{Line: 1, Column: 15, Byte: 14},
+												},
+											},
+										},
+									},
+								},
+							},
+							SrcRange: hcl.Range{
+								Start: hcl.Pos{Line: 1, Column: 5, Byte: 4},
+								End:   hcl.Pos{Line: 1, Column: 15, Byte: 14},
+							},
+							OpenRange: hcl.Range{
+								Start: hcl.Pos{Line: 1, Column: 5, Byte: 4},
+								End:   hcl.Pos{Line: 1, Column: 6, Byte: 5},
+							},
+						},
+						SrcRange: hcl.Range{
+							Start: hcl.Pos{Line: 1, Column: 1, Byte: 0},
+							End:   hcl.Pos{Line: 1, Column: 15, Byte: 14},
+						},
+						NameRange: hcl.Range{
+							Start: hcl.Pos{Line: 1, Column: 1, Byte: 0},
+							End:   hcl.Pos{Line: 1, Column: 2, Byte: 1},
+						},
+						EqualsRange: hcl.Range{
+							Start: hcl.Pos{Line: 1, Column: 3, Byte: 2},
+							End:   hcl.Pos{Line: 1, Column: 4, Byte: 3},
+						},
+					},
+				},
+				Blocks: Blocks{},
+				SrcRange: hcl.Range{
+					Start: hcl.Pos{Line: 1, Column: 1, Byte: 0},
+					End:   hcl.Pos{Line: 1, Column: 15, Byte: 14},
+				},
+				EndRange: hcl.Range{
+					Start: hcl.Pos{Line: 1, Column: 15, Byte: 14},
+					End:   hcl.Pos{Line: 1, Column: 15, Byte: 14},
+				},
+			},
+		},
 	}
 
 	for _, test := range tests {