Fix @sensitive handling in Display implementations on error shapes

CHANGELOG.next.toml

@@ -36,6 +36,12 @@ references = ["smithy-rs#1803"]
 meta = { "breaking" = true, "tada" = false, "bug" = false, "target" = "server"}
 author = "LukeMathWalker"
 
+[[smithy-rs]]
+message = "Sensitive fields in errors now respect @sensitive trait and are properly redacted."
+references = ["smithy-rs#1802"]
+meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "all" }
+author = "jjant"
+
 [[smithy-rs]]
 message = "Pokémon Service example code now runs clippy during build."
 references = ["smithy-rs#1727"]
@@ -117,7 +123,7 @@ author = "jdisanti"
 [[smithy-rs]]
 message = "Paginators now stop on encountering a duplicate token by default rather than panic. This behavior can be customized by toggling the `stop_on_duplicate_token` property on the paginator before calling `send`."
 references = ["aws-sdk-rust#620", "smithy-rs#1748"]
-meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "client"}
+meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "client" }
 author = "jdisanti"
 
 [[aws-sdk-rust]]

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/generators/StructureGenerator.kt

@@ -63,7 +63,7 @@ open class StructureGenerator(
     fun render(forWhom: CodegenTarget = CodegenTarget.CLIENT) {
         renderStructure()
         errorTrait?.also { errorTrait ->
-            ErrorGenerator(symbolProvider, writer, shape, errorTrait).render(forWhom)
+            ErrorGenerator(model, symbolProvider, writer, shape, errorTrait).render(forWhom)
         }
     }
 
@@ -109,6 +109,7 @@ open class StructureGenerator(
                 members.forEach { member ->
                     val memberName = symbolProvider.toMemberName(member)
                     val fieldValue = member.redactIfNecessary(model, "self.$memberName")
+
                     rust(
                         "formatter.field(${memberName.dq()}, &$fieldValue);",
                     )

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/generators/error/ErrorGenerator.kt

@@ -5,6 +5,7 @@
 
 package software.amazon.smithy.rust.codegen.core.smithy.generators.error
 
+import software.amazon.smithy.model.Model
 import software.amazon.smithy.model.shapes.StructureShape
 import software.amazon.smithy.model.traits.ErrorTrait
 import software.amazon.smithy.model.traits.RetryableTrait
@@ -19,10 +20,12 @@ import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.core.smithy.RuntimeType.Companion.StdError
 import software.amazon.smithy.rust.codegen.core.smithy.RustSymbolProvider
 import software.amazon.smithy.rust.codegen.core.smithy.isOptional
+import software.amazon.smithy.rust.codegen.core.util.REDACTION
 import software.amazon.smithy.rust.codegen.core.util.dq
 import software.amazon.smithy.rust.codegen.core.util.errorMessageMember
 import software.amazon.smithy.rust.codegen.core.util.getTrait
 import software.amazon.smithy.rust.codegen.core.util.letIf
+import software.amazon.smithy.rust.codegen.core.util.shouldRedact
 
 sealed class ErrorKind {
     abstract fun writable(runtimeConfig: RuntimeConfig): Writable
@@ -60,6 +63,7 @@ fun StructureShape.modeledRetryKind(errorTrait: ErrorTrait): ErrorKind? {
 }
 
 class ErrorGenerator(
+    private val model: Model,
     private val symbolProvider: RustSymbolProvider,
     private val writer: RustWriter,
     private val shape: StructureShape,
@@ -118,8 +122,12 @@ class ErrorGenerator(
                 }
                 write("write!(f, ${errorDesc.dq()})?;")
                 messageShape?.let {
-                    ifSet(it, symbolProvider.toSymbol(it), "&self.message") { field ->
-                        write("""write!(f, ": {}", $field)?;""")
+                    if (it.shouldRedact(model)) {
+                        write("""write!(f, ": {}", $REDACTION)?;""")
+                    } else {
+                        ifSet(it, symbolProvider.toSymbol(it), "&self.message") { field ->
+                            write("""write!(f, ": {}", $field)?;""")
+                        }
                     }
                 }
                 write("Ok(())")

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/util/Smithy.kt

@@ -84,14 +84,19 @@ fun ServiceShape.hasEventStreamOperations(model: Model): Boolean = operations.an
     model.expectShape(id, OperationShape::class.java).isEventStream(model)
 }
 
-fun Shape.redactIfNecessary(model: Model, safeToPrint: String): String =
+fun Shape.shouldRedact(model: Model): Boolean =
     when (this) {
-        is MemberShape -> model.expectShape(this.target).redactIfNecessary(model, safeToPrint)
-        else -> if (this.hasTrait<SensitiveTrait>()) {
-            "*** Sensitive Data Redacted ***".dq()
-        } else {
-            safeToPrint
-        }
+        is MemberShape -> model.expectShape(this.target).shouldRedact(model)
+        else -> this.hasTrait<SensitiveTrait>()
+    }
+
+const val REDACTION = "\"*** Sensitive Data Redacted ***\""
+
+fun Shape.redactIfNecessary(model: Model, safeToPrint: String): String =
+    if (this.shouldRedact(model)) {
+        REDACTION
+    } else {
+        safeToPrint
     }
 
 /*