From 061660ed9e9abe257012d2f1a4453d9a995aac88 Mon Sep 17 00:00:00 2001
From: Geoffrey Oxberry <geoffrey.oxberry@datadoghq.com>
Date: Thu, 21 May 2026 21:10:56 +0000
Subject: [PATCH] chore(clippy): forbid .expect() in production code

Adds `clippy::expect_used = "deny"` to the workspace lint set, mirroring the
existing `unwrap_used` policy. Configures `allow-expect-in-tests = true` in
clippy.toml so `#[cfg(test)]` modules remain free to use `.expect()`.

Pre-existing production `.expect()` sites are quarantined behind a
transitional `#![allow(clippy::expect_used)]` at the crate root of the four
affected library crates (lading, lading_capture, lading_payload,
lading_throttle). The lint fires immediately on new sites in any other
location. Cleanup PRs will remove each crate's quarantine atomically with
its violations.

Benches in lading_payload/benches/ get a permanent crate-root allow because
each bench is a separate crate root and clippy has no
`allow-expect-in-benches` knob to mirror the in-tests one.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 CHANGELOG.md                                   | 9 +++++++++
 Cargo.toml                                     | 1 +
 clippy.toml                                    | 5 ++++-
 lading/src/bin/captool/main.rs                 | 3 +++
 lading/src/bin/lading.rs                       | 4 ++++
 lading/src/bin/payloadtool.rs                  | 3 +++
 lading/src/lib.rs                              | 3 +++
 lading_capture/src/bin/fuzz_capture_harness.rs | 3 +++
 lading_capture/src/lib.rs                      | 4 ++++
 lading_payload/benches/apache_common.rs        | 4 ++++
 lading_payload/benches/ascii.rs                | 4 ++++
 lading_payload/benches/block.rs                | 4 ++++
 lading_payload/benches/datadog_logs.rs         | 4 ++++
 lading_payload/benches/dogstatsd.rs            | 4 ++++
 lading_payload/benches/fluent.rs               | 4 ++++
 lading_payload/benches/json.rs                 | 4 ++++
 lading_payload/benches/opentelemetry_log.rs    | 4 ++++
 lading_payload/benches/opentelemetry_metric.rs | 4 ++++
 lading_payload/benches/opentelemetry_traces.rs | 4 ++++
 lading_payload/benches/splunk_hec.rs           | 4 ++++
 lading_payload/benches/syslog.rs               | 4 ++++
 lading_payload/benches/templated_json.rs       | 4 ++++
 lading_payload/benches/trace_agent.rs          | 4 ++++
 lading_payload/src/lib.rs                      | 3 +++
 lading_throttle/src/lib.rs                     | 3 +++
 25 files changed, 96 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68a680e27..155d0ff87 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,15 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
+- Added `clippy::expect_used = "deny"` to the workspace-level lint set,
+  mirroring the existing `clippy::unwrap_used` policy, and set
+  `allow-expect-in-tests = true` in `clippy.toml`. Production `.expect()`
+  calls are now denied in library crates while `#[cfg(test)]` code is
+  unaffected. Crates with pre-existing production `.expect()` sites
+  (`lading`, `lading_capture`, `lading_payload`, `lading_throttle`) carry
+  a transitional `#![allow(clippy::expect_used)]` quarantine at their
+  crate roots; this allow will be removed crate-by-crate as the sites are
+  cleaned up.
 - Updated to rand 0.10.x
 - `dogstatsd` generator now supports configurable pools for the `|c:` (container
   ID), `|e:` (external data), and `|card:` (cardinality) origin detection
diff --git a/Cargo.toml b/Cargo.toml
index 677f879de..59dc3b83f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -77,6 +77,7 @@ perf = "deny"
 suspicious = "deny"
 complexity = "deny"
 unwrap_used = "deny"
+expect_used = "deny"
 mod_module_files = "deny"
 dbg_macro = "deny"
 print_stdout = "deny"
diff --git a/clippy.toml b/clippy.toml
index 1b3396338..09175b8a4 100644
--- a/clippy.toml
+++ b/clippy.toml
@@ -1,8 +1,11 @@
 # https://rust-lang.github.io/rust-clippy/master/index.html#doc_markdown
 doc-valid-idents = ["OpenTelemetry", "gRPC", ".."]
 
-# Allow unwrap() and print!/println! in test code without per-module suppressions
+# Allow unwrap()/expect() and print!/println! in test code without per-module
+# suppressions. `allow-expect-in-tests` mirrors `allow-unwrap-in-tests`; the
+# corresponding `clippy::expect_used` lint is set in the workspace Cargo.toml.
 allow-unwrap-in-tests = true
+allow-expect-in-tests = true
 allow-print-in-tests = true
 
 # https://rust-lang.github.io/rust-clippy/master/index.html#disallowed_types
diff --git a/lading/src/bin/captool/main.rs b/lading/src/bin/captool/main.rs
index 62371ea5f..23c39a396 100644
--- a/lading/src/bin/captool/main.rs
+++ b/lading/src/bin/captool/main.rs
@@ -1,6 +1,9 @@
 //! Capture analysis tool for lading capture files.
 
 #![expect(clippy::print_stdout)]
+// Quarantine: workspace denies `clippy::expect_used`, but this binary still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
 
 mod analyze;
 
diff --git a/lading/src/bin/lading.rs b/lading/src/bin/lading.rs
index 6161fac55..932af5f5f 100644
--- a/lading/src/bin/lading.rs
+++ b/lading/src/bin/lading.rs
@@ -1,5 +1,9 @@
 //! Main lading binary for load testing.
 
+// Quarantine: workspace denies `clippy::expect_used`, but this binary still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
+
 use std::{
     env,
     fmt::{self, Display},
diff --git a/lading/src/bin/payloadtool.rs b/lading/src/bin/payloadtool.rs
index 0e90d2a9b..77e12b289 100644
--- a/lading/src/bin/payloadtool.rs
+++ b/lading/src/bin/payloadtool.rs
@@ -2,6 +2,9 @@
 
 #![expect(clippy::print_stdout)]
 #![expect(clippy::print_stderr)]
+// Quarantine: workspace denies `clippy::expect_used`, but this binary still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
 
 /// Memory allocation tracking for payloadtool statistics.
 ///
diff --git a/lading/src/lib.rs b/lading/src/lib.rs
index f301d63ee..4c1aac577 100644
--- a/lading/src/lib.rs
+++ b/lading/src/lib.rs
@@ -8,6 +8,9 @@
 #![deny(clippy::cargo)]
 #![expect(clippy::cast_precision_loss)]
 #![expect(clippy::multiple_crate_versions)]
+// Quarantine: workspace denies `clippy::expect_used`, but this crate still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
 
 use http_body_util::BodyExt;
 
diff --git a/lading_capture/src/bin/fuzz_capture_harness.rs b/lading_capture/src/bin/fuzz_capture_harness.rs
index fc007a648..1331da56d 100644
--- a/lading_capture/src/bin/fuzz_capture_harness.rs
+++ b/lading_capture/src/bin/fuzz_capture_harness.rs
@@ -7,6 +7,9 @@
 
 #![expect(clippy::print_stderr)]
 #![allow(clippy::cast_precision_loss)]
+// Quarantine: workspace denies `clippy::expect_used`, but this binary still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
 
 use anyhow::{Context, Result};
 use arbitrary::Arbitrary;
diff --git a/lading_capture/src/lib.rs b/lading_capture/src/lib.rs
index a3ad883e1..c0a1b4c5a 100644
--- a/lading_capture/src/lib.rs
+++ b/lading_capture/src/lib.rs
@@ -1,5 +1,9 @@
 //! Crate regarding Lading's 'capture' files
 
+// Quarantine: workspace denies `clippy::expect_used`, but this crate still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
+
 use std::time::Instant;
 
 use manager::HISTORICAL_SENDER;
diff --git a/lading_payload/benches/apache_common.rs b/lading_payload/benches/apache_common.rs
index 48efbecb7..9e0b2bd5a 100644
--- a/lading_payload/benches/apache_common.rs
+++ b/lading_payload/benches/apache_common.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Apache Common log payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Serialize, apache_common};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/ascii.rs b/lading_payload/benches/ascii.rs
index aec42b66f..9bd20dbdc 100644
--- a/lading_payload/benches/ascii.rs
+++ b/lading_payload/benches/ascii.rs
@@ -3,6 +3,10 @@
 //! Paired with SMP regression experiments in `experiments/regression/cases/http_ascii_*`.
 //! If throughput sizes here change, update the corresponding SMP experiments and vice versa.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Serialize, ascii};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/block.rs b/lading_payload/benches/block.rs
index 53c880dd6..6fca9a537 100644
--- a/lading_payload/benches/block.rs
+++ b/lading_payload/benches/block.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Block Cache operations.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::Config;
 use lading_payload::block::Cache;
diff --git a/lading_payload/benches/datadog_logs.rs b/lading_payload/benches/datadog_logs.rs
index 848176bc5..6cab87057 100644
--- a/lading_payload/benches/datadog_logs.rs
+++ b/lading_payload/benches/datadog_logs.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Datadog Logs payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{DatadogLog, Serialize};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/dogstatsd.rs b/lading_payload/benches/dogstatsd.rs
index cdbf6ab7f..be6379852 100644
--- a/lading_payload/benches/dogstatsd.rs
+++ b/lading_payload/benches/dogstatsd.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for `DogStatsD` payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Serialize, dogstatsd};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/fluent.rs b/lading_payload/benches/fluent.rs
index e94a313c2..964c4ebe0 100644
--- a/lading_payload/benches/fluent.rs
+++ b/lading_payload/benches/fluent.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Fluent payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Fluent, Serialize};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/json.rs b/lading_payload/benches/json.rs
index f50002399..03dd1b6b2 100644
--- a/lading_payload/benches/json.rs
+++ b/lading_payload/benches/json.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for JSON payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Json, Serialize};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/opentelemetry_log.rs b/lading_payload/benches/opentelemetry_log.rs
index 5091a9beb..c0389862f 100644
--- a/lading_payload/benches/opentelemetry_log.rs
+++ b/lading_payload/benches/opentelemetry_log.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for OpenTelemetry log payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{OpentelemetryLogs, Serialize, opentelemetry::log::Config};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/opentelemetry_metric.rs b/lading_payload/benches/opentelemetry_metric.rs
index 587ebeb3a..126ed5775 100644
--- a/lading_payload/benches/opentelemetry_metric.rs
+++ b/lading_payload/benches/opentelemetry_metric.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for OpenTelemetry metric payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::common::config::ConfRange;
 use lading_payload::{
diff --git a/lading_payload/benches/opentelemetry_traces.rs b/lading_payload/benches/opentelemetry_traces.rs
index 818055638..9e3a7ed53 100644
--- a/lading_payload/benches/opentelemetry_traces.rs
+++ b/lading_payload/benches/opentelemetry_traces.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for OpenTelemetry trace payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::opentelemetry::trace::{
     AttributeConfig, AttributeValueConfig, Config, DatabaseServiceConfig, GrpcServiceConfig,
diff --git a/lading_payload/benches/splunk_hec.rs b/lading_payload/benches/splunk_hec.rs
index f6c6f332c..720bf8f6c 100644
--- a/lading_payload/benches/splunk_hec.rs
+++ b/lading_payload/benches/splunk_hec.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Splunk HEC payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Serialize, SplunkHec};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/syslog.rs b/lading_payload/benches/syslog.rs
index 10b51d9e9..eccd6805f 100644
--- a/lading_payload/benches/syslog.rs
+++ b/lading_payload/benches/syslog.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Syslog 5424 payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Serialize, Syslog5424};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/benches/templated_json.rs b/lading_payload/benches/templated_json.rs
index 5c0f0c0a1..b815513d4 100644
--- a/lading_payload/benches/templated_json.rs
+++ b/lading_payload/benches/templated_json.rs
@@ -9,6 +9,10 @@
 //! which exercises every `ValueGenerator` tag so the numbers reflect realistic
 //! template complexity.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use std::path::Path;
 use std::time::Duration;
 
diff --git a/lading_payload/benches/trace_agent.rs b/lading_payload/benches/trace_agent.rs
index 3915977da..1025e236f 100644
--- a/lading_payload/benches/trace_agent.rs
+++ b/lading_payload/benches/trace_agent.rs
@@ -1,5 +1,9 @@
 //! Benchmarks for Datadog trace agent payload generation.
 
+// `.expect()` is permitted in benches; workspace denies `clippy::expect_used`
+// for production code.
+#![allow(clippy::expect_used)]
+
 use criterion::{BatchSize, BenchmarkId, Criterion, Throughput, criterion_group, criterion_main};
 use lading_payload::{Serialize, trace_agent::v04};
 use rand::{SeedableRng, rngs::SmallRng};
diff --git a/lading_payload/src/lib.rs b/lading_payload/src/lib.rs
index b6ef8fbe6..3f412a84f 100644
--- a/lading_payload/src/lib.rs
+++ b/lading_payload/src/lib.rs
@@ -5,6 +5,9 @@
 #![deny(clippy::cargo)]
 #![allow(clippy::cast_precision_loss)]
 #![allow(clippy::multiple_crate_versions)]
+// Quarantine: workspace denies `clippy::expect_used`, but this crate still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
 
 use std::{
     io::{self, Write},
diff --git a/lading_throttle/src/lib.rs b/lading_throttle/src/lib.rs
index 493a0907e..c1e22c340 100644
--- a/lading_throttle/src/lib.rs
+++ b/lading_throttle/src/lib.rs
@@ -6,6 +6,9 @@
 #![deny(clippy::cargo)]
 #![allow(clippy::cast_precision_loss)]
 #![allow(clippy::multiple_crate_versions)]
+// Quarantine: workspace denies `clippy::expect_used`, but this crate still has
+// production `.expect()` sites awaiting cleanup. Remove once cleaned up.
+#![allow(clippy::expect_used)]
 
 use async_trait::async_trait;
 use serde::{Deserialize, Serialize};