we only want to send diagnostics for deeply nested deprecations in certain locations

Mainly terminal locations for the value where they are used, such as the config of a resource, for_each, outputs.
We don't want to evaluate the deprecation deeply when it comes to values where the value is not yet used, e.g. locals
This is because if e.g. a deeply nested value is deprecated it should still be ok for the entire object to be in a local
whereas the same object should give a warning in e.g. an output

internal/deprecation/deprecation.go

@@ -37,19 +37,31 @@ func (d *Deprecations) SuppressModuleCallDeprecation(addr addrs.Module) {
 
 // Validate checks the given value for deprecation marks and returns diagnostics
 // for each deprecation found, unless deprecation warnings are suppressed for the given module.
-// It does not check for deeply nested deprecation marks.
-func (d *Deprecations) Validate(value cty.Value, module addrs.Module, rng *hcl.Range) (cty.Value, tfdiags.Diagnostics) {
-	var diags tfdiags.Diagnostics
-	deprecationMarks := marks.GetDeprecationMarks(value)
-	if len(deprecationMarks) == 0 {
-		return value, diags
-	}
 
+// This is appropriate for non-terminal values (values that can be referenced) only.
+// If the value can not be referenced, use ValidateDeep or ValidateAsConfig instead.
+func (d *Deprecations) Validate(value cty.Value, module addrs.Module, rng *hcl.Range) (cty.Value, tfdiags.Diagnostics) {
+	deprecationMarks := marks.GetDeprecationMarks(value)
 	notDeprecatedValue := marks.RemoveDeprecationMarks(value)
+	return notDeprecatedValue, d.deprecationMarksToDiagnostics(deprecationMarks, module, rng)
+}
+
+// ValidateDeep does the same as Validate but checks deeply nested deprecation marks as well.
+func (d *Deprecations) ValidateDeep(value cty.Value, module addrs.Module, rng *hcl.Range) (cty.Value, tfdiags.Diagnostics) {
+	deprecationMarks := marks.GetDeprecationMarksDeep(value)
+	notDeprecatedValue := marks.RemoveDeprecationMarksDeep(value)
+	return notDeprecatedValue, d.deprecationMarksToDiagnostics(deprecationMarks, module, rng)
+}
+
+func (d *Deprecations) deprecationMarksToDiagnostics(deprecationMarks []marks.DeprecationMark, module addrs.Module, rng *hcl.Range) tfdiags.Diagnostics {
+	var diags tfdiags.Diagnostics
+	if len(deprecationMarks) == 0 {
+		return diags
+	}
 
 	// Check if we need to suppress deprecation warnings for this module call.
 	if d.IsModuleCallDeprecationSuppressed(module) {
-		return notDeprecatedValue, diags
+		return diags
 	}
 
 	for _, depMark := range deprecationMarks {
@@ -66,8 +78,7 @@ func (d *Deprecations) Validate(value cty.Value, module addrs.Module, rng *hcl.R
 		}
 		diags = diags.Append(diag)
 	}
-
-	return notDeprecatedValue, diags
+	return diags
 }
 
 // ValidateAsConfig checks the given value for deprecation marks and returns diagnostics

internal/lang/marks/marks.go

@@ -68,9 +68,30 @@ func GetDeprecationMarks(val cty.Value) []DeprecationMark {
 	return FilterDeprecationMarks(marks)
 }
 
+// GetDeprecationMarksDeep returns all deprecation marks present on the given
+// cty.Value or any nested values.
+func GetDeprecationMarksDeep(val cty.Value) []DeprecationMark {
+	_, marks := val.UnmarkDeep()
+	return FilterDeprecationMarks(marks)
+}
+
 // RemoveDeprecationMarks returns a copy of the given cty.Value with all
 // deprecation marks removed.
 func RemoveDeprecationMarks(val cty.Value) cty.Value {
+	newVal, marks := val.Unmark()
+
+	for mark := range marks {
+		if _, ok := mark.(DeprecationMark); !ok {
+			newVal = newVal.Mark(mark)
+		}
+	}
+
+	return newVal
+}
+
+// RemoveDeprecationMarksDeep returns a copy of the given cty.Value with all
+// deprecation marks deeply removed.
+func RemoveDeprecationMarksDeep(val cty.Value) cty.Value {
 	newVal, pvms := val.UnmarkDeepWithPaths()
 	otherPvms := RemoveAll(pvms, Deprecation)
 	return newVal.MarkWithPaths(otherPvms)

internal/terraform/context_plan2_test.go

@@ -7477,6 +7477,17 @@ output "test_output2" {
 				End:      hcl.Pos{Line: 7, Column: 27, Byte: 97},
 			},
 		},
+	).Append(
+		&hcl.Diagnostic{
+			Severity: hcl.DiagWarning,
+			Summary:  "Deprecated value used",
+			Detail:   "Please stop using this",
+			Subject: &hcl.Range{
+				Filename: filepath.Join(m.Module.SourceDir, "main.tf"),
+				Start:    hcl.Pos{Line: 7, Column: 10, Byte: 80},
+				End:      hcl.Pos{Line: 7, Column: 27, Byte: 97},
+			},
+		},
 	))
 }
 

internal/terraform/eval_conditions.go

@@ -107,7 +107,7 @@ func validateCheckRule(addr addrs.CheckRule, rule *configs.CheckRule, ctx EvalCo
 	errorMessage, moreDiags := lang.EvalCheckErrorMessage(rule.ErrorMessage, hclCtx, &addr)
 	diags = diags.Append(moreDiags)
 
-	_, deprecationDiags := ctx.Deprecations().Validate(errorMessage, ctx.Path().Module(), rule.ErrorMessage.Range().Ptr())
+	_, deprecationDiags := ctx.Deprecations().ValidateDeep(errorMessage, ctx.Path().Module(), rule.ErrorMessage.Range().Ptr())
 	diags = diags.Append(deprecationDiags)
 
 	// NOTE: We've discarded any other marks the string might have been carrying,
@@ -170,7 +170,7 @@ func evalCheckRule(addr addrs.CheckRule, rule *configs.CheckRule, ctx EvalContex
 	}
 
 	// We don't care about the returned value here, only the diagnostics
-	_, deprecationDiags := ctx.Deprecations().Validate(resultVal, addr.ModuleInstance().Module(), rule.Condition.Range().Ptr())
+	_, deprecationDiags := ctx.Deprecations().ValidateDeep(resultVal, addr.ModuleInstance().Module(), rule.Condition.Range().Ptr())
 	diags = diags.Append(deprecationDiags)
 
 	var err error

internal/terraform/eval_count.go

@@ -102,7 +102,7 @@ func evaluateCountExpressionValue(expr hcl.Expression, ctx EvalContext) (cty.Val
 		})
 	}
 
-	countVal, deprecationDiags := ctx.Deprecations().Validate(countVal, ctx.Path().Module(), expr.Range().Ptr())
+	countVal, deprecationDiags := ctx.Deprecations().ValidateDeep(countVal, ctx.Path().Module(), expr.Range().Ptr())
 	diags = diags.Append(deprecationDiags)
 
 	// Sensitive values are allowed in count but not for_each. This is a

internal/terraform/node_output.go

@@ -519,7 +519,7 @@ If you do intend to export this data, annotate the output value as sensitive by
 	}
 
 	if n.Config.DeprecatedSet {
-		val = marks.RemoveDeprecationMarks(val)
+		val = marks.RemoveDeprecationMarksDeep(val)
 		if n.Addr.Module.IsRoot() {
 			diags = diags.Append(&hcl.Diagnostic{
 				Severity: hcl.DiagError,
@@ -530,7 +530,7 @@ If you do intend to export this data, annotate the output value as sensitive by
 		}
 	} else if n.Config.Expr != nil {
 		var deprecationDiags tfdiags.Diagnostics
-		val, deprecationDiags = ctx.Deprecations().Validate(val, n.ModulePath(), n.Config.Expr.Range().Ptr())
+		val, deprecationDiags = ctx.Deprecations().ValidateDeep(val, n.ModulePath(), n.Config.Expr.Range().Ptr())
 		diags = diags.Append(deprecationDiags)
 	}