Generate server code compliant with the linter

Author: Fahad Zubair

buildSrc/src/main/kotlin/CodegenTestCommon.kt

@@ -286,12 +286,11 @@ fun Project.registerGenerateCargoConfigTomlTask(outputDir: File) {
         // is completed, warnings can be prohibited in rustdoc by setting `rustdocflags` to `-D warnings`.
         doFirst {
             outputDir.resolve(".cargo").mkdirs()
-            // TODO(MSRV1.82 follow-up): Restore `"--deny", "warnings"` once lints are fixed in the server runtime crates
             outputDir.resolve(".cargo/config.toml")
                 .writeText(
                     """
                     [build]
-                    rustflags = ["--cfg", "aws_sdk_unstable"]
+                    rustflags = ["--deny", "warnings", "--cfg", "aws_sdk_unstable"]
                     """.trimIndent(),
                 )
         }

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/ServerBuilderGenerator.kt

@@ -351,9 +351,25 @@ class ServerBuilderGenerator(
                     if (!constrainedTypeHoldsFinalType(member)) varExpr = "($varExpr).into()"
 
                     if (wrapInMaybeConstrained) {
-                        conditionalBlock("input.map(##[allow(clippy::redundant_closure)] |v| ", ")", conditional = symbol.isOptional()) {
-                            conditionalBlock("Box::new(", ")", conditional = hasBox) {
-                                rust("$maybeConstrainedVariant($varExpr)")
+                        // TODO(https://github.com/rust-lang/rust-clippy/issues/14789):
+                        // Temporary fix for `#[allow(clippy::redundant_closure)]` not working in `rustc` version 1.82.
+                        // The issue occurs specifically when we generate code in the form:
+                        // ```rust
+                        // input.map(|v| MaybeConstrained(v))
+                        // ```
+                        // This pattern triggers a clippy warning about redundant closures, even with the allow attribute.
+                        // For this specific pattern, we directly use the constructor function reference:
+                        // ```rust
+                        // input.map(MaybeConstrained)
+                        // ```
+                        // Other cases like `Box::new(v)` or `v.into()` are valid closure usages and remain unchanged.
+                        if (symbol.isOptional() && varExpr == "v") {
+                            rust("input.map($maybeConstrainedVariant)")
+                        } else {
+                            conditionalBlock("input.map(##[allow(clippy::redundant_closure)] |v| ", ")", conditional = symbol.isOptional()) {
+                                conditionalBlock("Box::new(", ")", conditional = hasBox) {
+                                    rust("$maybeConstrainedVariant($varExpr)")
+                                }
                             }
                         }
                     } else {

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/ServerBuilderGeneratorCommon.kt

@@ -27,6 +27,7 @@ import software.amazon.smithy.model.shapes.LongShape
 import software.amazon.smithy.model.shapes.MapShape
 import software.amazon.smithy.model.shapes.MemberShape
 import software.amazon.smithy.model.shapes.NumberShape
+import software.amazon.smithy.model.shapes.Shape
 import software.amazon.smithy.model.shapes.ShortShape
 import software.amazon.smithy.model.shapes.StringShape
 import software.amazon.smithy.model.shapes.TimestampShape
@@ -84,8 +85,23 @@ fun generateFallbackCodeToDefaultValue(
     symbolProvider: RustSymbolProvider,
     publicConstrainedTypes: Boolean,
 ) {
-    var defaultValue = defaultValue(model, runtimeConfig, symbolProvider, member)
     val targetShape = model.expectShape(member.target)
+    // TODO(https://github.com/rust-lang/rust-clippy/issues/14789):
+    // Temporary fix for `#[allow(clippy::redundant_closure)]` not working in `rustc` version 1.82.
+    // The issue occurs specifically when we generate code in the form:
+    // ```rust
+    // .unwrap_or_else(HashMap::new())
+    // ```
+    // Instead of the linter suggested code:
+    // ```rust
+    // .unwrap_or_default()
+    // ```
+    if (isTargetListOrMap(targetShape, member)) {
+        writer.rustTemplate(".unwrap_or_default()")
+        return
+    }
+
+    var defaultValue = defaultValue(model, runtimeConfig, symbolProvider, member)
     val targetSymbol = symbolProvider.toSymbol(targetShape)
     // We need an .into() conversion to create defaults for the server types. A larger scale refactoring could store this information in the
     // symbol, however, retrieving it in this manner works for the moment.
@@ -125,6 +141,22 @@ fun generateFallbackCodeToDefaultValue(
     }
 }
 
+private fun isTargetListOrMap(
+    targetShape: Shape?,
+    member: MemberShape,
+): Boolean {
+    if (targetShape is ListShape) {
+        val node = member.expectTrait<DefaultTrait>().toNode()!!
+        check(node is ArrayNode && node.isEmpty)
+        return true
+    } else if (targetShape is MapShape) {
+        val node = member.expectTrait<DefaultTrait>().toNode()!!
+        check(node is ObjectNode && node.isEmpty)
+        return true
+    }
+    return false
+}
+
 /**
  * Returns a writable to construct a Rust value of the correct type holding the modeled `@default` value on the
  * [member] shape.

tools/ci-build/Dockerfile

@@ -206,9 +206,8 @@ ENV PATH=/opt/cargo/bin:$PATH \
     RUST_STABLE_VERSION=${rust_stable_version} \
     RUST_NIGHTLY_VERSION=${rust_nightly_version} \
     CARGO_INCREMENTAL=0 \
-    # TODO(MSRV1.82 follow-up): Restore them once lints are fixed in the server runtime crates
-    # RUSTDOCFLAGS="-D warnings" \
-    # RUSTFLAGS="-D warnings" \
+    RUSTDOCFLAGS="-D warnings" \
+    RUSTFLAGS="-D warnings" \
     LANG=en_US.UTF-8 \
     LC_ALL=en_US.UTF-8
 # SMITHY_RS_DOCKER_BUILD_IMAGE indicates to build scripts that they are being built inside of the Docker build image.

tools/ci-scripts/check-rust-runtimes

@@ -31,9 +31,7 @@ do
 
     echo -e "## ${C_YELLOW}Running 'cargo doc' on ${runtime_path}...${C_RESET}"
 
-    # TODO(MSRV1.82 follow-up): Restore `-Dwarnings` once lints are fixed in aws-smithy-http-server-python:
-    # "error: unexpected `cfg` condition name: `addr_of`"
-    RUSTDOCFLAGS="--cfg docsrs" cargo +"${RUST_NIGHTLY_VERSION}" doc --no-deps --document-private-items --all-features
+    RUSTDOCFLAGS="--cfg docsrs -Dwarnings" cargo +"${RUST_NIGHTLY_VERSION}" doc --no-deps --document-private-items --all-features
 
     echo -e "## ${C_YELLOW}Running 'cargo minimal-versions check' on ${runtime_path}...${C_RESET}"
     # Print out the cargo tree with minimal versions for easier debugging