fix: Avoid duplicated warnings

.changes/v1.12/BUG FIXES-20250226-171815.yaml

@@ -0,0 +1,5 @@
+kind: BUG FIXES
+body: 'Avoid reporting duplicate attribute-associated diagnostics, such as "Available Write-only Attribute Alternative"'
+time: 2025-02-26T17:18:15.521208Z
+custom:
+    Issue: "36579"

internal/backend/local/backend_plan.go

@@ -76,7 +76,7 @@ func (b *Local) opPlan(
 		b.ContextOpts = new(terraform.ContextOpts)
 	}
 
-	// Get our context
+	// Set up backend and get our context
 	lr, configSnap, opState, ctxDiags := b.localRun(op)
 	diags = diags.Append(ctxDiags)
 	if ctxDiags.HasErrors() {
@@ -120,7 +120,9 @@ func (b *Local) opPlan(
 	// NOTE: We intentionally don't stop here on errors because we always want
 	// to try to present a partial plan report and, if the user chose to,
 	// generate a partial saved plan file for external analysis.
-	diags = diags.Append(planDiags)
+	// Plan() may produce some diagnostic warnings which were already
+	// produced when setting up context above, so we deduplicate them here.
+	diags = diags.AppendWithoutDuplicates(planDiags...)
 
 	// Even if there are errors we need to handle anything that may be
 	// contained within the plan, so only exit if there is no data at all.

internal/backend/remote-state/s3/backend_test.go

@@ -1935,9 +1935,7 @@ func TestBackendConfig_Proxy(t *testing.T) {
 			raw, diags := testBackendConfigDiags(t, New(), backend.TestWrapConfig(config))
 			b := raw.(*Backend)
 
-			if diff := cmp.Diff(diags, tc.expectedDiags, tfdiags.DiagnosticComparer); diff != "" {
-				t.Errorf("unexpected diagnostics difference: %s", diff)
-			}
+			tfdiags.AssertDiagnosticsMatch(t, diags, tc.expectedDiags)
 
 			client := b.awsConfig.HTTPClient
 			bClient, ok := client.(*awshttp.BuildableClient)

internal/terraform/context_plan_ephemeral_test.go

@@ -5,6 +5,7 @@ package terraform
 
 import (
 	"fmt"
+	"path/filepath"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -63,6 +64,11 @@ module "child" {
 					Severity: hcl.DiagError,
 					Summary:  "Ephemeral value not allowed",
 					Detail:   "This output value is not declared as returning an ephemeral value, so it cannot be set to a result derived from an ephemeral value.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "child", "main.tf"),
+						Start:    hcl.Pos{Line: 3, Column: 13, Byte: 30},
+						End:      hcl.Pos{Line: 3, Column: 31, Byte: 48},
+					},
 				})
 			},
 		},
@@ -109,6 +115,11 @@ resource "test_object" "test" {
 					Severity: hcl.DiagError,
 					Summary:  "Invalid use of ephemeral value",
 					Detail:   `Ephemeral values are not valid for "test_string", because it is not a write-only attribute and must be persisted to state.`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 6, Column: 17, Byte: 88},
+						End:      hcl.Pos{Line: 6, Column: 52, Byte: 123},
+					},
 				})
 			},
 		},
@@ -164,13 +175,17 @@ resource "test_object" "test" {
 					Severity: hcl.DiagError,
 					Summary:  "Invalid for_each argument",
 					Detail:   `The given "for_each" value is derived from an ephemeral value, which means that Terraform cannot persist it between plan/apply rounds. Use only non-ephemeral values to specify a resource's instance keys.`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 4, Column: 14, Byte: 83},
+						End:      hcl.Pos{Line: 4, Column: 55, Byte: 124},
+					},
 				})
 			},
 		},
 
 		"resource expansion - count": {
 			module: map[string]string{
-
 				"main.tf": `
 ephemeral "ephem_resource" "data" {}
 resource "test_object" "test" {
@@ -184,6 +199,11 @@ resource "test_object" "test" {
 					Severity: hcl.DiagError,
 					Summary:  "Invalid count argument",
 					Detail:   `The given "count" is derived from an ephemeral value, which means that Terraform cannot persist it between plan/apply rounds. Use only non-ephemeral values to specify the number of resource instances.`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 4, Column: 11, Byte: 80},
+						End:      hcl.Pos{Line: 4, Column: 53, Byte: 122},
+					},
 				})
 			},
 		},
@@ -210,6 +230,11 @@ module "child" {
 					Severity: hcl.DiagError,
 					Summary:  "Invalid for_each argument",
 					Detail:   `The given "for_each" value is derived from an ephemeral value, which means that Terraform cannot persist it between plan/apply rounds. Use only non-ephemeral values to specify a resource's instance keys.`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 5, Column: 16, Byte: 71},
+						End:      hcl.Pos{Line: 5, Column: 57, Byte: 112},
+					},
 				})
 			},
 		},
@@ -234,6 +259,11 @@ module "child" {
 					Severity: hcl.DiagError,
 					Summary:  "Invalid count argument",
 					Detail:   `The given "count" is derived from an ephemeral value, which means that Terraform cannot persist it between plan/apply rounds. Use only non-ephemeral values to specify the number of resource instances.`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 4, Column: 13, Byte: 67},
+						End:      hcl.Pos{Line: 4, Column: 55, Byte: 109},
+					},
 				})
 			},
 		},
@@ -261,6 +291,11 @@ resource "test_object" "test" {
 						Severity: hcl.DiagError,
 						Summary:  "Invalid for_each argument",
 						Detail:   `The given "for_each" value is derived from an ephemeral value, which means that Terraform cannot persist it between plan/apply rounds. Use only non-ephemeral values to specify a resource's instance keys.`,
+						Subject: &hcl.Range{
+							Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+							Start:    hcl.Pos{Line: 11, Column: 16, Byte: 207},
+							End:      hcl.Pos{Line: 11, Column: 57, Byte: 248},
+						},
 					},
 				)
 			},
@@ -288,6 +323,11 @@ module "child" {
 					Severity: hcl.DiagError,
 					Summary:  "Ephemeral value not allowed",
 					Detail:   "This output value is not declared as returning an ephemeral value, so it cannot be set to a result derived from an ephemeral value.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "child", "main.tf"),
+						Start:    hcl.Pos{Line: 6, Column: 13, Byte: 132},
+						End:      hcl.Pos{Line: 6, Column: 64, Byte: 183},
+					},
 				})
 			},
 		},
@@ -322,6 +362,11 @@ module "child" {
 					Severity: hcl.DiagError,
 					Summary:  "Ephemeral value not allowed",
 					Detail:   "This output value is not declared as returning an ephemeral value, so it cannot be set to a result derived from an ephemeral value.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "child", "main.tf"),
+						Start:    hcl.Pos{Line: 14, Column: 13, Byte: 245},
+						End:      hcl.Pos{Line: 14, Column: 78, Byte: 310},
+					},
 				})
 			},
 		},
@@ -378,17 +423,32 @@ check "check_using_ephemeral_value" {
 					Severity: hcl.DiagWarning,
 					Summary:  "Check block assertion failed",
 					Detail:   "Fine to persist",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 6, Column: 17, Byte: 104},
+						End:      hcl.Pos{Line: 6, Column: 60, Byte: 147},
+					},
 				})
 				diags = diags.Append(&hcl.Diagnostic{
 					Severity: hcl.DiagWarning,
 					Summary:  "Check block assertion failed",
 					Detail:   "This check failed, but has an invalid error message as described in the other accompanying messages.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 10, Column: 17, Byte: 217},
+						End:      hcl.Pos{Line: 10, Column: 60, Byte: 260},
+					},
 				})
 				diags = diags.Append(&hcl.Diagnostic{
 					Severity: hcl.DiagWarning,
 					Summary:  "Error message refers to ephemeral values",
 					Detail: "The error expression used to explain this condition refers to ephemeral values, so Terraform will not display the resulting message." +
 						"\n\nYou can correct this by removing references to ephemeral values, or by using the ephemeralasnull() function on the references to not reveal ephemeral data.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 11, Column: 21, Byte: 281},
+						End:      hcl.Pos{Line: 11, Column: 83, Byte: 343},
+					},
 				})
 				return diags
 			},
@@ -451,14 +511,29 @@ module "child" {
 					Severity: hcl.DiagError,
 					Summary:  "Ephemeral value not allowed",
 					Detail:   "This output value is not declared as returning an ephemeral value, so it cannot be set to a result derived from an ephemeral value.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "child", "main.tf"),
+						Start:    hcl.Pos{Line: 15, Column: 13, Byte: 376},
+						End:      hcl.Pos{Line: 15, Column: 33, Byte: 396},
+					},
 				}, &hcl.Diagnostic{
 					Severity: hcl.DiagError,
 					Summary:  "Ephemeral value not allowed",
 					Detail:   "This output value is not declared as returning an ephemeral value, so it cannot be set to a result derived from an ephemeral value.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "child", "main.tf"),
+						Start:    hcl.Pos{Line: 18, Column: 13, Byte: 435},
+						End:      hcl.Pos{Line: 18, Column: 31, Byte: 453},
+					},
 				}, &hcl.Diagnostic{
 					Severity: hcl.DiagError,
 					Summary:  "Ephemeral value not allowed",
 					Detail:   "This output value is not declared as returning an ephemeral value, so it cannot be set to a result derived from an ephemeral value.",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "child", "main.tf"),
+						Start:    hcl.Pos{Line: 21, Column: 13, Byte: 491},
+						End:      hcl.Pos{Line: 21, Column: 30, Byte: 508},
+					},
 				})
 			},
 		},
@@ -483,6 +558,11 @@ ephemeral "ephem_resource" "data" {
 					Severity: hcl.DiagError,
 					Summary:  "Resource precondition failed",
 					Detail:   "value should not be 2",
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 8, Column: 19, Byte: 116},
+						End:      hcl.Pos{Line: 8, Column: 40, Byte: 137},
+					},
 				})
 			},
 		},
@@ -507,6 +587,11 @@ ephemeral "ephem_resource" "data" {
 					Severity: hcl.DiagError,
 					Summary:  "Resource postcondition failed",
 					Detail:   `value should be "pass"`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 8, Column: 19, Byte: 117},
+						End:      hcl.Pos{Line: 8, Column: 39, Byte: 137},
+					},
 				})
 			},
 		},
@@ -541,12 +626,22 @@ output "out" {
 					Detail: fmt.Sprintf(`The error message included a sensitive value, so it will not be displayed.
 
 This was checked by the validation rule at %s.`, m.Module.Variables["ephem"].Validations[0].DeclRange.String()),
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 2, Column: 1, Byte: 1},
+						End:      hcl.Pos{Line: 2, Column: 17, Byte: 17},
+					},
 				}).Append(&hcl.Diagnostic{
 					Severity: hcl.DiagError,
 					Summary:  "Error message refers to ephemeral values",
 					Detail: `The error expression used to explain this condition refers to ephemeral values. Terraform will not display the resulting message.
 
 You can correct this by removing references to ephemeral values, or by carefully using the ephemeralasnull() function if the expression will not reveal the ephemeral data.`,
+					Subject: &hcl.Range{
+						Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+						Start:    hcl.Pos{Line: 8, Column: 21, Byte: 142},
+						End:      hcl.Pos{Line: 8, Column: 76, Byte: 197},
+					},
 				})
 			},
 		},

internal/terraform/node_resource_plan_partialexp.go

@@ -201,6 +201,7 @@ func (n *nodePlannablePartialExpandedResource) managedResourceExecute(ctx EvalCo
 	}
 
 	unmarkedConfigVal, _ := configVal.UnmarkDeep()
+	log.Printf("[TRACE] Validating partially expanded config for %q", n.addr)
 	validateResp := provider.ValidateResourceConfig(
 		providers.ValidateResourceConfigRequest{
 			TypeName: n.addr.Resource().Type,

internal/terraform/node_resource_validate.go

@@ -5,6 +5,7 @@ package terraform
 
 import (
 	"fmt"
+	"log"
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
@@ -390,6 +391,7 @@ func (n *NodeValidatableResource) validateResource(ctx EvalContext) tfdiags.Diag
 
 		// Use unmarked value for validate request
 		unmarkedConfigVal, _ := configVal.UnmarkDeep()
+		log.Printf("[TRACE] Validating config for %q", n.Addr)
 		req := providers.ValidateResourceConfigRequest{
 			TypeName:           n.Config.Type,
 			Config:             unmarkedConfigVal,

internal/terraform/terraform_test.go

@@ -92,7 +92,10 @@ func testModuleWithSnapshot(t *testing.T, name string) (*configs.Config, *config
 func testModuleInline(t testing.TB, sources map[string]string) *configs.Config {
 	t.Helper()
 
-	cfgPath := t.TempDir()
+	cfgPath, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	for path, configStr := range sources {
 		dir := filepath.Dir(path)

internal/tfdiags/compare.go

@@ -7,10 +7,8 @@ import "github.com/google/go-cmp/cmp"
 // DiagnosticComparer returns a cmp.Option that can be used with
 // the package github.com/google/go-cmp/cmp.
 //
-// The comparer checks these match between the diagnostics:
-// 1) Severity
-// 2) Description
-// 3) Attribute cty.Path, if present
+// The comparer relies on the underlying Diagnostic implementing
+// [ComparableDiagnostic].
 //
 // Example usage:
 //
@@ -20,18 +18,15 @@ var DiagnosticComparer cmp.Option = cmp.Comparer(diagnosticComparerSimple)
 // diagnosticComparerSimple returns false when a difference is identified between
 // the two Diagnostic arguments.
 func diagnosticComparerSimple(l, r Diagnostic) bool {
-	if l.Severity() != r.Severity() {
-		return false
-	}
-	if l.Description() != r.Description() {
+	ld, ok := l.(ComparableDiagnostic)
+	if !ok {
 		return false
 	}
 
-	// Do the diagnostics originate from the same attribute name, if any?
-	lp := GetAttribute(l)
-	rp := GetAttribute(r)
-	if len(lp) != len(rp) {
+	rd, ok := r.(ComparableDiagnostic)
+	if !ok {
 		return false
 	}
-	return lp.Equals(rp)
+
+	return ld.Equals(rd)
 }

internal/tfdiags/compare_test.go

@@ -81,27 +81,6 @@ func TestDiagnosticComparer(t *testing.T) {
 			}(),
 			expectDiff: true,
 		},
-		// Scenarios where diagnostics will be considered equavalent, even if they aren't fully the same
-		"reports that diagnostics match even if sources (Subject) are different; ignored in simple comparison": {
-			diag1: hclDiagnostic{&baseError},
-			diag2: func() Diagnostic {
-				d := baseError
-				d.Subject = &hcl.Range{
-					Filename: "foobar.tf",
-					Start: hcl.Pos{
-						Line:   0,
-						Column: 0,
-						Byte:   0,
-					},
-					End: hcl.Pos{
-						Line:   1,
-						Column: 1,
-						Byte:   1,
-					},
-				}
-				return hclDiagnostic{&d}
-			}(),
-		},
 		"reports that diagnostics match even if sources (Context) are different; ignored in simple comparison": {
 			diag1: hclDiagnostic{&baseError},
 			diag2: func() Diagnostic {