Implement unreferenced variable validation

internal/decoder/decoder.go

@@ -7,9 +7,11 @@ import (
 	"context"
 
 	"github.com/hashicorp/hcl-lang/decoder"
+	"github.com/hashicorp/hcl-lang/lang"
 	"github.com/hashicorp/hcl-lang/reference"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/terraform-ls/internal/codelens"
+	"github.com/hashicorp/terraform-ls/internal/decoder/validations"
 	ilsp "github.com/hashicorp/terraform-ls/internal/lsp"
 	lsp "github.com/hashicorp/terraform-ls/internal/protocol"
 	"github.com/hashicorp/terraform-ls/internal/state"
@@ -91,5 +93,10 @@ func DecoderContext(ctx context.Context) decoder.DecoderContext {
 		}
 	}
 
+	validations := []lang.ValidationFunc{
+		validations.UnReferencedOrigin,
+	}
+	dCtx.Validations = append(dCtx.Validations, validations...)
+
 	return dCtx
 }

internal/decoder/validations/unreferenced_origin.go

@@ -0,0 +1,52 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validations
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/hcl-lang/decoder"
+	"github.com/hashicorp/hcl-lang/lang"
+	"github.com/hashicorp/hcl-lang/reference"
+	"github.com/hashicorp/hcl/v2"
+)
+
+func UnReferencedOrigin(ctx context.Context) lang.DiagnosticsMap {
+	diagsMap := make(lang.DiagnosticsMap)
+
+	pathCtx, err := decoder.PathCtx(ctx)
+	if err != nil {
+		return diagsMap
+	}
+
+	for _, origin := range pathCtx.ReferenceOrigins {
+		matchableOrigin, ok := origin.(reference.MatchableOrigin)
+		if !ok {
+			continue
+		}
+
+		foo := matchableOrigin.Address()[0]
+		if foo.String() != "var" {
+			continue
+		}
+
+		_, ok = pathCtx.ReferenceTargets.Match(matchableOrigin)
+		if !ok {
+			// target not found
+			fileName := origin.OriginRange().Filename
+			d := &hcl.Diagnostic{
+				Severity: hcl.DiagError,
+				Summary:  fmt.Sprintf("No declaration found for %q", matchableOrigin.Address()),
+				Subject:  origin.OriginRange().Ptr(),
+			}
+			diagsMap[fileName] = diagsMap[fileName].Append(d)
+
+			continue
+		}
+
+	}
+
+	return diagsMap
+}

internal/decoder/validations/unreferenced_origin_test.go

@@ -0,0 +1,120 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package validations
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/hashicorp/hcl-lang/decoder"
+	"github.com/hashicorp/hcl-lang/lang"
+	"github.com/hashicorp/hcl-lang/reference"
+	"github.com/hashicorp/hcl/v2"
+)
+
+func TestUnReferencedOrigin(t *testing.T) {
+	tests := []struct {
+		name    string
+		origins reference.Origins
+		want    lang.DiagnosticsMap
+	}{
+		{
+			name: "undeclared variable",
+			origins: reference.Origins{
+				reference.LocalOrigin{
+					Range: hcl.Range{
+						Filename: "test.tf",
+						Start:    hcl.Pos{},
+						End:      hcl.Pos{},
+					},
+					Addr: lang.Address{
+						lang.RootStep{Name: "var"},
+						lang.AttrStep{Name: "foo"},
+					},
+				},
+			},
+			want: lang.DiagnosticsMap{
+				"test.tf": hcl.Diagnostics{
+					&hcl.Diagnostic{
+						Severity: hcl.DiagError,
+						Summary:  "No declaration found for \"var.foo\"",
+						Subject: &hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{},
+							End:      hcl.Pos{},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "many undeclared variables",
+			origins: reference.Origins{
+				reference.LocalOrigin{
+					Range: hcl.Range{
+						Filename: "test.tf",
+						Start:    hcl.Pos{Line: 1, Column: 1, Byte: 0},
+						End:      hcl.Pos{Line: 1, Column: 10, Byte: 10},
+					},
+					Addr: lang.Address{
+						lang.RootStep{Name: "var"},
+						lang.AttrStep{Name: "foo"},
+					},
+				},
+				reference.LocalOrigin{
+					Range: hcl.Range{
+						Filename: "test.tf",
+						Start:    hcl.Pos{Line: 2, Column: 1, Byte: 0},
+						End:      hcl.Pos{Line: 2, Column: 10, Byte: 10},
+					},
+					Addr: lang.Address{
+						lang.RootStep{Name: "var"},
+						lang.AttrStep{Name: "wakka"},
+					},
+				},
+			},
+			want: lang.DiagnosticsMap{
+				"test.tf": hcl.Diagnostics{
+					&hcl.Diagnostic{
+						Severity: hcl.DiagError,
+						Summary:  "No declaration found for \"var.foo\"",
+						Subject: &hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 1, Column: 1, Byte: 0},
+							End:      hcl.Pos{Line: 1, Column: 10, Byte: 10},
+						},
+					},
+					&hcl.Diagnostic{
+						Severity: hcl.DiagError,
+						Summary:  "No declaration found for \"var.wakka\"",
+						Subject: &hcl.Range{
+							Filename: "test.tf",
+							Start:    hcl.Pos{Line: 2, Column: 1, Byte: 0},
+							End:      hcl.Pos{Line: 2, Column: 10, Byte: 10},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("%2d-%s", i, tt.name), func(t *testing.T) {
+			ctx := context.Background()
+
+			pathCtx := &decoder.PathContext{
+				ReferenceOrigins: tt.origins,
+			}
+
+			ctx = decoder.WithPathContext(ctx, pathCtx)
+
+			diags := UnReferencedOrigin(ctx)
+			if diff := cmp.Diff(tt.want["test.tf"], diags["test.tf"]); diff != "" {
+				t.Fatalf("unexpected diagnostics: %s", diff)
+			}
+		})
+	}
+}