find-non-lambda-logs

name	find-non-lambda-logs
description	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)

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).