fix: builder accessor method naming conflicts

.changelog/fix-builder-accessor-naming.md

@@ -0,0 +1,9 @@
+---
+applies_to: ["client", "server"]
+authors: ["haydenbaker", "nated0g"]
+references: ["smithy-rs#4338"]
+breaking: false
+new_feature: false
+bug_fix: true
+---
+Fix a duplicate `set_meta` definition when an error structure has a `meta` member. The generated struct field is already renamed to `meta_value`, so the builder's setter and getter now match (`set_meta_value`, `get_meta_value`, `meta_value`). Setters for other renamed members (e.g. `default`, `build`, `builder`) are unchanged.

aws/codegen-aws-sdk/src/main/kotlin/software/amazon/smithy/rustsdk/SmokeTestsDecorator.kt

@@ -154,7 +154,7 @@ class SmokeTestsBuilderKindBehavior(val codegenContext: CodegenContext) : Instan
     override fun hasFallibleBuilder(shape: StructureShape): Boolean =
         BuilderGenerator.hasFallibleBuilder(shape, codegenContext.symbolProvider)
 
-    override fun setterName(memberShape: MemberShape): String = memberShape.setterName()
+    override fun setterName(memberShape: MemberShape): String = memberShape.setterName(codegenContext.symbolProvider)
 
     override fun doesSetterTakeInOption(memberShape: MemberShape): Boolean = true
 }

aws/codegen-aws-sdk/src/main/kotlin/software/amazon/smithy/rustsdk/endpoints/OperationInputTestGenerator.kt

@@ -186,7 +186,7 @@ class OperationInputTestGenerator(_ctx: ClientCodegenContext, private val test:
             testOperationInput.operationParams.members.forEach { (key, value) ->
                 val member = operationInput.expectMember(key.value)
                 rustTemplate(
-                    ".${member.setterName()}(#{value})",
+                    ".${member.setterName(ctx.symbolProvider)}(#{value})",
                     "value" to instantiator.generate(member, value),
                 )
             }

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/ClientBuilderInstantiator.kt

@@ -15,6 +15,7 @@ import software.amazon.smithy.rust.codegen.core.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.core.rustlang.writable
 import software.amazon.smithy.rust.codegen.core.smithy.generators.BuilderGenerator
 import software.amazon.smithy.rust.codegen.core.smithy.generators.BuilderInstantiator
+import software.amazon.smithy.rust.codegen.core.smithy.generators.setterName
 
 class ClientBuilderInstantiator(private val clientCodegenContext: ClientCodegenContext) : BuilderInstantiator {
     override fun setField(
@@ -25,6 +26,10 @@ class ClientBuilderInstantiator(private val clientCodegenContext: ClientCodegenC
         return setFieldWithSetter(builder, value, field)
     }
 
+    override fun setterProvider(field: MemberShape): String {
+        return field.setterName(clientCodegenContext.symbolProvider)
+    }
+
     /**
      * For the client, we finalize builders with error correction enabled
      */

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/ClientInstantiator.kt

@@ -23,7 +23,7 @@ class ClientBuilderKindBehavior(val codegenContext: CodegenContext) : Instantiat
     override fun hasFallibleBuilder(shape: StructureShape): Boolean =
         BuilderGenerator.hasFallibleBuilder(shape, codegenContext.symbolProvider)
 
-    override fun setterName(memberShape: MemberShape): String = memberShape.setterName()
+    override fun setterName(memberShape: MemberShape): String = memberShape.setterName(codegenContext.symbolProvider)
 
     override fun doesSetterTakeInOption(memberShape: MemberShape): Boolean = true
 }

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/client/FluentBuilderGenerator.kt

@@ -368,11 +368,11 @@ class FluentBuilderGenerator(
                     else -> renderInputHelper(member, memberName, coreType)
                 }
                 // pure setter
-                val setterName = member.setterName()
+                val setterName = member.setterName(symbolProvider)
                 val optionalInputType = outerType.asOptional()
                 renderInputHelper(member, setterName, optionalInputType)
 
-                val getterName = member.getterName()
+                val getterName = member.getterName(symbolProvider)
                 renderGetterHelper(member, getterName, optionalInputType)
             }
         }
@@ -438,7 +438,7 @@ class FluentBuilderGenerator(
             """
             Appends an item to `${member.memberName}`.
 
-            To override the contents of this collection use [`${member.setterName()}`](Self::${member.setterName()}).
+            To override the contents of this collection use [`${member.setterName(symbolProvider)}`](Self::${member.setterName(symbolProvider)}).
             """,
         )
         documentShape(member, model)
@@ -468,7 +468,7 @@ class FluentBuilderGenerator(
             """
             Adds a key-value pair to `${member.memberName}`.
 
-            To override the contents of this collection use [`${member.setterName()}`](Self::${member.setterName()}).
+            To override the contents of this collection use [`${member.setterName(symbolProvider)}`](Self::${member.setterName(symbolProvider)}).
             """,
         )
         documentShape(member, model)

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/client/FluentClientGenerator.kt

@@ -368,7 +368,7 @@ private fun generateOperationShapeDocs(
         val builderInputDoc = memberShape.asFluentBuilderInputDoc(symbolProvider)
         val builderInputLink = docLink("$fluentBuilderFullyQualifiedName::${symbolProvider.toMemberName(memberShape)}")
         val builderSetterDoc = memberShape.asFluentBuilderSetterDoc(symbolProvider)
-        val builderSetterLink = docLink("$fluentBuilderFullyQualifiedName::${memberShape.setterName()}")
+        val builderSetterLink = docLink("$fluentBuilderFullyQualifiedName::${memberShape.setterName(symbolProvider)}")
 
         val docTrait = memberShape.getMemberTrait(model, DocumentationTrait::class.java).orNull()
         val docs =
@@ -449,7 +449,7 @@ internal fun MemberShape.asFluentBuilderInputDoc(symbolProvider: SymbolProvider)
  *  _NOTE: This function generates the setter type names that appear under **"The fluent builder is configurable:"**_
  */
 private fun MemberShape.asFluentBuilderSetterDoc(symbolProvider: SymbolProvider): String {
-    val memberName = this.setterName()
+    val memberName = this.setterName(symbolProvider)
     val outerType = symbolProvider.toSymbol(this).rustType()
 
     return "$memberName(${outerType.asArgumentType(fullyQualified = false)})"

codegen-client/src/main/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/protocol/ProtocolParserGenerator.kt

@@ -264,7 +264,7 @@ class ProtocolParserGenerator(
             val member = binding.member
             val parsedValue = renderBindingParser(binding, operationShape, httpBindingGenerator, structuredDataParser)
             if (parsedValue != null) {
-                withBlock("output = output.${member.setterName()}(", ");") {
+                withBlock("output = output.${member.setterName(symbolProvider)}(", ");") {
                     parsedValue(this)
                 }
             }

codegen-client/src/test/kotlin/software/amazon/smithy/rust/codegen/client/smithy/generators/client/FluentClientGeneratorTest.kt

@@ -138,4 +138,92 @@ class FluentClientGeneratorTest {
 
         clientIntegrationTest(model)
     }
+
+    // Regression test for https://github.com/smithy-lang/smithy-rs/issues/4338: an error shape
+    // with a `meta` member used to produce a duplicate `set_meta` method on the generated builder
+    // because `ErrorGenerator` injects its own `set_meta` for `ErrorMetadata`. The fix renames
+    // only `meta` members (field, setter, getter) while leaving other members like `default`
+    // untouched so we don't introduce unrelated breaking changes.
+    @Test
+    fun `meta field on error shape does not collide with injected set_meta`() {
+        val model =
+            """
+            namespace com.example
+            use aws.protocols#awsJson1_0
+
+            @awsJson1_0
+            service TestService {
+                operations: [TestOperation],
+                version: "1"
+            }
+
+            operation TestOperation {
+                input: TestInput,
+                errors: [TestError]
+            }
+
+            structure TestInput {
+               meta: String,
+               other: String,
+               default: String
+            }
+
+            @error("client")
+            structure TestError {
+                meta: String,
+                message: String
+            }
+            """.asSmithyModel()
+
+        clientIntegrationTest(model) { codegenContext, rustCrate ->
+            rustCrate.integrationTest("meta_field_renamed") {
+                val moduleName = codegenContext.moduleUseName()
+                rustTemplate(
+                    """
+                    ##[test]
+                    fn test_meta_field_accessors() {
+                        let config = $moduleName::Config::builder()
+                            .endpoint_url("http://localhost:1234")
+                            .http_client(#{NeverClient}::new())
+                            .build();
+                        let client = $moduleName::Client::from_conf(config);
+
+                        // `meta` is renamed to `meta_value` for field, setter, and getter to
+                        // avoid the `ErrorMetadata` collision on error shapes.
+                        let builder = client.test_operation()
+                            .meta_value("test_meta")
+                            .set_meta_value(Some("test_meta_2".to_string()))
+                            .other("other_value")
+                            // `default` keeps `set_default` / `get_default` even though its field
+                            // is renamed to `default_value` — renaming the accessors would be an
+                            // unnecessary breaking change.
+                            .set_default(Some("default_value".to_string()));
+
+                        assert_eq!(*builder.get_meta_value(), Some("test_meta_2".to_string()));
+                        assert_eq!(*builder.get_other(), Some("other_value".to_string()));
+                        assert_eq!(*builder.get_default(), Some("default_value".to_string()));
+
+                        let input = builder.as_input();
+                        assert_eq!(*input.get_meta_value(), Some("test_meta_2".to_string()));
+
+                        // The error builder must compile without a duplicate `set_meta` — the
+                        // original bug — and `meta_value` must coexist with the injected error
+                        // metadata field.
+                        let _error = $moduleName::types::error::TestError::builder()
+                            .meta_value("user_meta")
+                            .message("boom")
+                            .meta(#{ErrorMetadata}::builder().code("TestError").build())
+                            .build();
+                    }
+                    """,
+                    "NeverClient" to
+                        CargoDependency.smithyHttpClientTestUtil(codegenContext.runtimeConfig).toType()
+                            .resolve("test_util::NeverClient"),
+                    "ErrorMetadata" to
+                        CargoDependency.smithyTypes(codegenContext.runtimeConfig).toType()
+                            .resolve("error::ErrorMetadata"),
+                )
+            }
+        }
+    }
 }

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

@@ -134,11 +134,33 @@ class OperationBuildError(private val runtimeConfig: RuntimeConfig) {
     }
 }
 
-// Setter names will never hit a reserved word and therefore never need escaping.
-fun MemberShape.setterName() = "set_${this.memberName.toSnakeCase()}"
+// Builder setters/getters keep the raw member name in almost all cases: setter names don't
+// collide with Rust reserved words, and renaming would be a breaking change for consumers of
+// the generated SDK. The one exception is members named `meta` on error-struct builders, where
+// `ErrorGenerator` injects a `set_meta` method for `ErrorMetadata` — we fall back to the
+// symbol-provider-renamed name (`meta_value`) there to avoid a duplicate definition.
+// See https://github.com/smithy-lang/smithy-rs/issues/4338.
+fun MemberShape.setterName(symbolProvider: SymbolProvider): String {
+    val raw = this.memberName.toSnakeCase()
+    val name =
+        if (raw == "meta") {
+            symbolProvider.toMemberName(this).removePrefix("r##")
+        } else {
+            raw
+        }
+    return "set_$name"
+}
 
-// Getter names will never hit a reserved word and therefore never need escaping.
-fun MemberShape.getterName() = "get_${this.memberName.toSnakeCase()}"
+fun MemberShape.getterName(symbolProvider: SymbolProvider): String {
+    val raw = this.memberName.toSnakeCase()
+    val name =
+        if (raw == "meta") {
+            symbolProvider.toMemberName(this).removePrefix("r##")
+        } else {
+            raw
+        }
+    return "get_$name"
+}
 
 class BuilderGenerator(
     private val model: Model,
@@ -192,7 +214,7 @@ class BuilderGenerator(
                         val memberName = member.memberName.toSnakeCase()
                         val setter =
                             if (symbolProvider.toSymbol(member).isOptional()) {
-                                member.setterName()
+                                member.setterName(symbolProvider)
                             } else {
                                 memberName
                             }
@@ -311,7 +333,7 @@ class BuilderGenerator(
 
         writer.documentShape(member, model)
         writer.deprecatedShape(member)
-        writer.rustBlock("pub fn ${member.setterName()}(mut self, input: ${inputType.render(true)}) -> Self") {
+        writer.rustBlock("pub fn ${member.setterName(symbolProvider)}(mut self, input: ${inputType.render(true)}) -> Self") {
             rust("self.$memberName = input; self")
         }
     }
@@ -333,7 +355,7 @@ class BuilderGenerator(
 
         writer.documentShape(member, model)
         writer.deprecatedShape(member)
-        writer.rustBlock("pub fn ${member.getterName()}(&self) -> &${inputType.render(true)}") {
+        writer.rustBlock("pub fn ${member.getterName(symbolProvider)}(&self) -> &${inputType.render(true)}") {
             rust("&self.$memberName")
         }
     }
@@ -409,7 +431,13 @@ class BuilderGenerator(
     ) {
         docs("Appends an item to `$memberName`.")
         rust("///")
-        docs("To override the contents of this collection use [`${member.setterName()}`](Self::${member.setterName()}).")
+        docs(
+            "To override the contents of this collection use [`${member.setterName(symbolProvider)}`](Self::${
+                member.setterName(
+                    symbolProvider,
+                )
+            }).",
+        )
         rust("///")
         documentShape(member, model, autoSuppressMissingDocs = false)
         deprecatedShape(member)
@@ -435,7 +463,13 @@ class BuilderGenerator(
     ) {
         docs("Adds a key-value pair to `$memberName`.")
         rust("///")
-        docs("To override the contents of this collection use [`${member.setterName()}`](Self::${member.setterName()}).")
+        docs(
+            "To override the contents of this collection use [`${member.setterName(symbolProvider)}`](Self::${
+                member.setterName(
+                    symbolProvider,
+                )
+            }).",
+        )
         rust("///")
         documentShape(member, model, autoSuppressMissingDocs = false)
         deprecatedShape(member)

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

@@ -33,12 +33,14 @@ interface BuilderInstantiator {
         mapErr: Writable? = null,
     ): Writable
 
+    fun setterProvider(field: MemberShape): String
+
     /** Set a field on a builder using the `$setterName` method. $value will be passed directly. */
     fun setFieldWithSetter(
         builder: String,
         value: Writable,
         field: MemberShape,
     ) = writable {
-        rustTemplate("$builder = $builder.${field.setterName()}(#{value})", "value" to value)
+        rustTemplate("$builder = $builder.${setterProvider(field)}(#{value})", "value" to value)
     }
 }

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/parse/CborParserGenerator.kt

@@ -271,7 +271,7 @@ class CborParserGenerator(
                     rustBlock("${member.memberName.dq()} =>") {
                         val callBuilderSetMemberFieldWritable =
                             writable {
-                                withBlock("builder.${member.setterName()}(", ")") {
+                                withBlock("builder.${member.setterName(symbolProvider)}(", ")") {
                                     conditionalBlock("Some(", ")", shouldWrapBuilderMemberSetterInputWithOption(member)) {
                                         val symbol = symbolProvider.toSymbol(member)
                                         if (symbol.isRustBoxed()) {

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/parse/EventStreamUnmarshallerGenerator.kt

@@ -273,7 +273,7 @@ class EventStreamUnmarshallerGenerator(
     }
 
     private fun RustWriter.renderUnmarshallEventHeader(member: MemberShape) {
-        withBlock("builder = builder.${member.setterName()}(", ");") {
+        withBlock("builder = builder.${member.setterName(symbolProvider)}(", ");") {
             conditionalBlock("Some(", ")", member.isOptional) {
                 when (val target = model.expectShape(member.target)) {
                     is BooleanShape -> rustTemplate("#{expect_fns}::expect_bool(header)?", *codegenScope)
@@ -306,7 +306,7 @@ class EventStreamUnmarshallerGenerator(
                 *codegenScope,
             )
         }
-        withBlock("builder = builder.${member.setterName()}(", ");") {
+        withBlock("builder = builder.${member.setterName(symbolProvider)}(", ");") {
             conditionalBlock("Some(", ")", member.isOptional) {
                 when (target) {
                     is BlobShape -> {

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/parse/JsonParserGenerator.kt

@@ -267,14 +267,14 @@ class JsonParserGenerator(
                     rustBlock("${jsonName(member).dq()} =>") {
                         when (codegenTarget) {
                             CodegenTarget.CLIENT -> {
-                                withBlock("builder = builder.${member.setterName()}(", ");") {
+                                withBlock("builder = builder.${member.setterName(symbolProvider)}(", ");") {
                                     deserializeMember(member)
                                 }
                             }
 
                             CodegenTarget.SERVER -> {
                                 if (symbolProvider.toSymbol(member).isOptional()) {
-                                    withBlock("builder = builder.${member.setterName()}(", ");") {
+                                    withBlock("builder = builder.${member.setterName(symbolProvider)}(", ");") {
                                         deserializeMember(member)
                                     }
                                 } else {
@@ -283,7 +283,7 @@ class JsonParserGenerator(
                                     rust(
                                         """
                                         {
-                                            builder = builder.${member.setterName()}(v);
+                                            builder = builder.${member.setterName(symbolProvider)}(v);
                                         }
                                         """,
                                     )

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/protocols/parse/XmlBindingTraitParserGenerator.kt

@@ -296,7 +296,7 @@ class XmlBindingTraitParserGenerator(
                         Ctx(tag = decoder, accum = "$builder.${symbolProvider.toMemberName(member)}.take()"),
                     )
                 }
-                rust("$builder = $builder.${member.setterName()}($temp);")
+                rust("$builder = $builder.${member.setterName(symbolProvider)}($temp);")
             }
             rustTemplate(
                 "_ => return Err(#{XmlDecodeError}::custom(\"expected ${member.xmlName()} tag\"))",
@@ -335,7 +335,7 @@ class XmlBindingTraitParserGenerator(
                             forceOptional = true,
                         )
                     }
-                    rust("$builder = $builder.${member.setterName()}($temp);")
+                    rust("$builder = $builder.${member.setterName(symbolProvider)}($temp);")
                 }
             }
         }