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find-non-lambda-logs

Testing & Quality
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Use when auditing or migrating Log calls — flags both interpolated Log.d/i/w/e that should use the lambda overload (allocation hygiene) and catch-block Log.w/e that interpolate ${e.message} but drop the throwable (lost stack traces)

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Find Non-Lambda Log Calls

Overview

Two related logging hygiene issues:

  1. Lambda overload missing. Log.d/i/w/e calls that use string interpolation without the lambda overload waste string allocation when the log level is filtered out in release builds.
  2. Throwable dropped in catch blocks. Log.w/e calls inside catch (e: ...) blocks that interpolate ${e.message} but don't pass e lose the stack trace, and log nothing useful when e.message is null (NPE, IOException with no message, etc.).

When to Use

  • After merging branches that add new logging
  • Periodic audit of logging hygiene
  • After migrating android.util.Log usages to the shared Log wrapper

What to Flag

Calls with string interpolation ($ in message) that do not pass a throwable:

// FLAG - interpolation without lambda, no throwable
Log.d("Tag", "Processing ${event.id}")
Log.w("Tag", "Failed for $url")

// IGNORE - passes throwable (lambda overload doesn't accept throwable)
Log.w("Tag", "Error: ${e.message}", e)
Log.e("Tag", "Failed for $url", throwable)

// IGNORE - no interpolation (no allocation benefit from lambda)
Log.d("Tag", "Initialization complete")

Search Commands

Important: Tags can be string literals ("Tag") or variables (tag, LOG_TAG). Run both patterns for each step.

Step 1: Find interpolated Log.d/Log.i (highest priority — filtered in release)

pattern: Log\.(d|i)\("[^"]+",\s*"[^"]*\$
type: kotlin

pattern: Log\.(d|i)\(\w+,\s*"[^"]*\$
type: kotlin

Step 2: Find interpolated Log.w/Log.e without throwable

pattern: Log\.(w|e)\("[^"]+",\s*"[^"]*\$
type: kotlin

pattern: Log\.(w|e)\(\w+,\s*"[^"]*\$
type: kotlin

Then manually exclude lines where a throwable is passed as third argument (ending with , e), , throwable), etc.). Check the actual line — a catch block catching e doesn't mean e is passed to the Log call.

Step 3: Find catch-block Log.w/e that drop the throwable

Among the Step 2 hits, the calls that interpolate ${e.message} (or ${t.message}, ${throwable.message}) but do not pass the exception itself are a separate bug — they lose the stack trace AND log a useless empty-ish line whenever the exception's message is null.

Quick filter:

pattern: Log\.(w|e)\([^)]*\$\{(e|t|throwable|cause)\.message\}[^)]*\)$
type: kotlin

Then for each hit, open the file and confirm the line is inside a catch (e: ...) block and does not pass e (or the matching name) as a third argument. False positives: extension functions / helpers that accept an e: SomeError parameter and forward it elsewhere.

Both Step 2 and Step 3 may flag the same line — handle Step 3 first (different fix), then apply Step 2 to whatever remains.

Step 4: Verify no android.util.Log leakage

pattern: android\.util\.Log\.(d|i|w|e|v)\(
type: kotlin

These bypass the Log.minLevel filter entirely. Exclude PlatformLog.android.kt which is the wrapper implementation.

Fix Patterns

Lambda overload (Step 1 + Step 2)

// Before
Log.d("Tag", "Processing event ${event.id} from ${relay.url}")

// After
Log.d("Tag") { "Processing event ${event.id} from ${relay.url}" }

Throwable overload (Step 3)

Switch to (tag, msg, throwable) — the lambda overload does not accept a throwable, so this case must use the eager-string form. Drop the redundant ${e.message} from the message text since the throwable already carries it.

// Before — stack trace lost, prints "...failed: null" if e.message is null
try { groupManager.clearAllState() } catch (e: Exception) {
    Log.w("MarmotManager") { "clearAllState failed: ${e.message}" }
}

// After — full stack trace logged
try { groupManager.clearAllState() } catch (e: Exception) {
    Log.w("MarmotManager", "clearAllState failed", e)
}

Trade-off: the message string is allocated eagerly even when warn is filtered, but warn-level catch logs are rare-event paths so this cost is negligible compared to losing diagnostic detail.

Do NOT Convert

  • To lambda: calls passing a Throwable parameter — the lambda overload (tag) { message } has no throwable parameter.
  • Static string calls with no $ interpolation — no allocation benefit.
  • Commented-out log calls.
  • Informational/intentional log of e.message outside a catch block (rare; usually means the exception was already handled and only the message is meaningful).
in message) that do **not** pass a throwable:\n\n```kotlin\n// FLAG - interpolation without lambda, no throwable\nLog.d(\"Tag\", \"Processing ${event.id}\")\nLog.w(\"Tag\", \"Failed for $url\")\n\n// IGNORE - passes throwable (lambda overload doesn't accept throwable)\nLog.w(\"Tag\", \"Error: ${e.message}\", e)\nLog.e(\"Tag\", \"Failed for $url\", throwable)\n\n// IGNORE - no interpolation (no allocation benefit from lambda)\nLog.d(\"Tag\", \"Initialization complete\")\n```\n\n## Search Commands\n\n**Important:** Tags can be string literals (`\"Tag\"`) or variables (`tag`, `LOG_TAG`). Run both patterns for each step.\n\n### Step 1: Find interpolated Log.d/Log.i (highest priority — filtered in release)\n\n```\npattern: Log\\.(d|i)\\(\"[^\"]+\",\\s*\"[^\"]*\\$\ntype: kotlin\n```\n```\npattern: Log\\.(d|i)\\(\\w+,\\s*\"[^\"]*\\$\ntype: kotlin\n```\n\n### Step 2: Find interpolated Log.w/Log.e without throwable\n\n```\npattern: Log\\.(w|e)\\(\"[^\"]+\",\\s*\"[^\"]*\\$\ntype: kotlin\n```\n```\npattern: Log\\.(w|e)\\(\\w+,\\s*\"[^\"]*\\$\ntype: kotlin\n```\n\nThen **manually exclude** lines where a throwable is passed as third argument (ending with `, e)`, `, throwable)`, etc.). Check the actual line — a catch block catching `e` doesn't mean `e` is passed to the Log call.\n\n### Step 3: Find catch-block Log.w/e that drop the throwable\n\nAmong the Step 2 hits, the calls that interpolate `${e.message}` (or `${t.message}`, `${throwable.message}`) but do not pass the exception itself are a separate bug — they lose the stack trace AND log a useless empty-ish line whenever the exception's message is null.\n\nQuick filter:\n\n```\npattern: Log\\.(w|e)\\([^)]*\\$\\{(e|t|throwable|cause)\\.message\\}[^)]*\\)$\ntype: kotlin\n```\n\nThen for each hit, open the file and confirm the line is **inside a `catch (e: ...)` block** and **does not pass `e` (or the matching name) as a third argument**. False positives: extension functions / helpers that accept an `e: SomeError` parameter and forward it elsewhere.\n\nBoth Step 2 and Step 3 may flag the same line — handle Step 3 first (different fix), then apply Step 2 to whatever remains.\n\n### Step 4: Verify no android.util.Log leakage\n\n```\npattern: android\\.util\\.Log\\.(d|i|w|e|v)\\(\ntype: kotlin\n```\n\nThese bypass the `Log.minLevel` filter entirely. Exclude `PlatformLog.android.kt` which is the wrapper implementation.\n\n## Fix Patterns\n\n### Lambda overload (Step 1 + Step 2)\n\n```kotlin\n// Before\nLog.d(\"Tag\", \"Processing event ${event.id} from ${relay.url}\")\n\n// After\nLog.d(\"Tag\") { \"Processing event ${event.id} from ${relay.url}\" }\n```\n\n### Throwable overload (Step 3)\n\nSwitch to `(tag, msg, throwable)` — the lambda overload does **not** accept a throwable, so this case must use the eager-string form. Drop the redundant `${e.message}` from the message text since the throwable already carries it.\n\n```kotlin\n// Before — stack trace lost, prints \"...failed: null\" if e.message is null\ntry { groupManager.clearAllState() } catch (e: Exception) {\n Log.w(\"MarmotManager\") { \"clearAllState failed: ${e.message}\" }\n}\n\n// After — full stack trace logged\ntry { groupManager.clearAllState() } catch (e: Exception) {\n Log.w(\"MarmotManager\", \"clearAllState failed\", e)\n}\n```\n\nTrade-off: the message string is allocated eagerly even when warn is filtered, but warn-level catch logs are rare-event paths so this cost is negligible compared to losing diagnostic detail.\n\n## Do NOT Convert\n\n- **To lambda:** calls passing a `Throwable` parameter — the lambda overload `(tag) { message }` has no throwable parameter.\n- Static string calls with no ` find-non-lambda-logs — Agent Skill guide | OpenParable interpolation — no allocation benefit.\n- Commented-out log calls.\n- Informational/intentional log of `e.message` *outside* a catch block (rare; usually means the exception was already handled and only the message is meaningful).\n"}],"versionEndpoint":"/skill/api/version"}