Add Log4j2IsEnabledToSlf4j Refaster recipe to convert isEnabled(Level) level guards to SLF4J isXEnabled() calls.#294
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timtebeek
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Perfect addition, thanks! Should help code to conform to standards, and recipes to chain more easily.
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…rom 3.27.2 to 3.29.0 [skip ci] Bumps [org.openrewrite.recipe:rewrite-logging-frameworks](https://github.com/openrewrite/rewrite-logging-frameworks) from 3.27.2 to 3.29.0. Release notes *Sourced from [org.openrewrite.recipe:rewrite-logging-frameworks's releases](https://github.com/openrewrite/rewrite-logging-frameworks/releases).* > 3.29.0 > ------ > > What's Changed > -------------- > > * Regenerate recipes.csv by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-logging-frameworks#292](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/292) > * Fix re-escaping of control characters when rebuilding Java string literals in logging recipes. by [`@motlin`](https://github.com/motlin) in [openrewrite/rewrite-logging-frameworks#293](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/293) > * Add Log4j2IsEnabledToSlf4j Refaster recipe to convert isEnabled(Level) level guards to SLF4J isXEnabled() calls. by [`@motlin`](https://github.com/motlin) in [openrewrite/rewrite-logging-frameworks#294](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/294) > > **Full Changelog**: <openrewrite/rewrite-logging-frameworks@v3.28.0...v3.29.0> > > 3.28.0 > ------ > > What's Changed > -------------- > > * Renew log4j 1.2.17 reference suppression to 2026-06-01 by [`@Jenson3210`](https://github.com/Jenson3210) in [openrewrite/rewrite-logging-frameworks#287](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/287) > * Update log4j-api TypeTable to 2.26.0 by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-logging-frameworks#288](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/288) > * Preserve formatting when ParameterizedLogging has nothing to parameterize by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-logging-frameworks#290](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/290) > > **Full Changelog**: <openrewrite/rewrite-logging-frameworks@v3.27.0...v3.28.0> > > v3.27.3 > ------- > > What's Changed > -------------- > > * OpenRewrite [v8.81.6](https://github.com/openrewrite/rewrite/releases/tag/v8.81.6) > * Fix IndexOutOfBoundsException when JUL placeholders exceed argument count by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-logging-frameworks#284](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/284) > * Fix exception consumed by format placeholder in CompleteExceptionLogging by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-logging-frameworks#285](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/pull/285) > > **Full Changelog**: <openrewrite/rewrite-logging-frameworks@v3.26.0...v3.27.3> Commits * [`944b9c2`](openrewrite/rewrite-logging-frameworks@944b9c2) Add Log4j2IsEnabledToSlf4j Refaster recipe to convert isEnabled(Level) level ... * [`246f4d3`](openrewrite/rewrite-logging-frameworks@246f4d3) Fix re-escaping of control characters when rebuilding Java string literals in... * [`d5537a4`](openrewrite/rewrite-logging-frameworks@d5537a4) Update Gradle wrapper 9.5.1 * [`58e431b`](openrewrite/rewrite-logging-frameworks@58e431b) Regenerate recipes.csv ([#292](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/issues/292)) * [`28afd35`](openrewrite/rewrite-logging-frameworks@28afd35) Remove explicit test dependencies * [`14f50ad`](openrewrite/rewrite-logging-frameworks@14f50ad) Preserve formatting when ParameterizedLogging has nothing to parameterize ([#2](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/issues/2)... * [`32e22cb`](openrewrite/rewrite-logging-frameworks@32e22cb) Update log4j-api TypeTable to 2.26.0 ([#288](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/issues/288)) * [`b7824c6`](openrewrite/rewrite-logging-frameworks@b7824c6) OpenRewrite recipe best practices * [`43fc6c2`](openrewrite/rewrite-logging-frameworks@43fc6c2) Renew log4j 1.2.17 reference suppression to 2026-06-01 ([#287](https://redirect.github.com/openrewrite/rewrite-logging-frameworks/issues/287)) * See full diff in [compare view](openrewrite/rewrite-logging-frameworks@v3.27.2...v3.29.0)
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What's changed?
Adds a new Refaster recipe
Log4j2IsEnabledToSlf4jthat converts Log4j 2.xLogger.isEnabled(Level.X)level guards to the corresponding SLF4JisXEnabled()calls:isEnabled(Level.TRACE)/isEnabled(Level.ALL)isTraceEnabled()isEnabled(Level.DEBUG)isDebugEnabled()isEnabled(Level.INFO)isInfoEnabled()isEnabled(Level.WARN)isWarnEnabled()isEnabled(Level.ERROR)/isEnabled(Level.FATAL)isErrorEnabled()It's wired into
Log4j2ToSlf4j1(inslf4j.yml) ahead of theChangeTypestep that retypesorg.apache.logging.log4j.Loggertoorg.slf4j.Logger, so the Refaster templates still match while the Log4j type is present.What's your motivation?
The Log4j to SLF4J migration retyped the logger but left
isEnabled(Level.X)guards untouched, leaving code that no longer compiles - SLF4J'sLoggerhas noisEnabled(Level)method.Anything in particular you'd like reviewers to focus on?
Why
isXEnabled()rather than SLF4J 2.x'sisEnabledForLevel(Level)?SLF4J 2.0 added
boolean isEnabledForLevel(org.slf4j.event.Level), which would preserve the parameterized form. I deliberately did not use it because:Migrate Log4j 2.x to SLF4J 1.x(and is reused byLog4j1ToSlf4j1).isEnabledForLeveldoes not exist in SLF4J 1.7, so emitting it would produce code that doesn't compile for the 1.x users this recipe targets.isXEnabled()compiles on both 1.x and 2.x.org.slf4j.event.Levelonly definesTRACE, DEBUG, INFO, WARN, ERROR. Log4j'sALLandFATALhave no SLF4J enum equivalent, so they'd require a fallback mapping regardless of which method is used.Lossy level mappings:
ALLtoisTraceEnabled()andFATALtoisErrorEnabled(), since SLF4J has noALLorFATALlevel. These collapse into the existing recipes via a second@BeforeTemplateper class - flagging in case a different convention is preferred.Recipe ordering in
slf4j.yml: must run before theLoggerChangeType.