Linter Compiler Plugin

Linter is a Scala static analysis compiler plugin which adds compile-time checks for various possible bugs, inefficiencies, and style problems.

Donations

Please help support the development of Linter.

Usage from sbt

Add Linter to your project by appending this line to your build.sbt:

addCompilerPlugin("org.psywerx.hairyfotr" %% "linter" % "0.1.17")

If you would always like to have the latest changes, snapshots are also available:

resolvers += Resolver.sonatypeRepo("snapshots")

addCompilerPlugin("org.psywerx.hairyfotr" %% "linter" % "0.1-SNAPSHOT")

Usage from maven

Add Linter to your project by updating your pom.xml with a "compilerPlugin" section.

<configuration>
  <compilerPlugins>
    <compilerPlugin>
      <groupId>org.psywerx.hairyfotr</groupId>
      <artifactId>linter_2.11</artifactId>
      <version>0.1.17</version>
    </compilerPlugin>
  </compilerPlugins>
</configuration>

Usage from Jenkins

Use your usual building method and Jenkins Warnings Plugin.

Manual usage

Another possible way to use Linter is to manually download and use these snapshot jars:<br> Scala 2.12, Scala 2.11, Scala 2.10, <br> Scala 2.9.3 (outdated)

terminal:
  scalac -Xplugin:<path-to-linter-jar>.jar ...

sbt: (in build.sbt)
  scalacOptions += "-Xplugin:<path-to-linter-jar>.jar"

maven: (in pom.xml inside scala-maven-plugin configuration)
  <configuration>
    <args>
      <arg>-Xplugin:<path-to-linter-jar>.jar</arg>
    </args>
  </configuration>

Note: If you have instructions for another build tool or IDE, please make a pull request.

Displaying check names

To disable displaying check names in the output use the printWarningNames switch:

scalacOptions += "-P:linter:printWarningNames:false"

Note: Set to true by default since version 0.1.17

Enabling/Disabling checks

Checks can be disabled using a plus-separated list of check names:

scalacOptions += "-P:linter:disable:UseHypot+CloseSourceFile+OptionOfOption"

Or only specific checks can be enabled using:

scalacOptions += "-P:linter:enable-only:UseHypot+CloseSourceFile+OptionOfOption"

Suppressing false positives

If you believe some warnings are false positives, you can ignore them with a code comment:

scala> val x = math.pow(5, 1/3d) + 1/0 // linter:ignore UseCbrt,DivideByZero // ignores UseCbrt and DivideByZero
<console>:8: warning: Integer division detected in an expression assigned to a floating point variable.
              math.pow(5, 1/3d) + 1/0 // linter:ignore UseCbrt,DivideByZero // ignores UseCbrt and DivideByZero
                                ^
scala> val x = math.pow(5, 1/3d) + 1/0 // linter:ignore // ignores all warnings

Note: Please consider reporting false positives so that they can be removed in future versions.

List of implemented checks (123)

UnextendedSealedTrait, UnlikelyEquality, UseLog1p, UseLog10, UseExpm1, UseHypot, UseCbrt, UseSqrt, SuspiciousPow, UseExp, UseAbsNotSqrtSquare, UseIsNanNotSelfComparison, UseIsNanNotNanComparison, UseSignum, BigDecimalNumberFormat, BigDecimalPrecisionLoss, ReflexiveAssignment, CloseSourceFile, JavaConverters, ContainsTypeMismatch, NumberInstanceOf, PatternMatchConstant, PreferIfToBooleanMatch, IdenticalCaseBodies, IdenticalCaseConditions, ReflexiveComparison, YodaConditions, UseConditionDirectly, UseIfExpression, UnnecessaryElseBranch, DuplicateIfBranches, IdenticalIfElseCondition, MergeNestedIfs, VariableAssignedUnusedValue, MalformedSwap, IdenticalIfCondition, IdenticalStatements, IndexingWithNegativeNumber, OptionOfOption, UndesirableTypeInference, AssigningOptionToNull, WrapNullWithOption, AvoidOptionStringSize, AvoidOptionCollectionSize, UseGetOrElseOnOption, UseOptionOrNull, UseOptionGetOrElse, UseExistsNotFindIsDefined, UseExistsNotFilterIsEmpty, UseFindNotFilterHead, UseContainsNotExistsEquals, UseQuantifierFuncNotFold, UseFuncNotReduce, UseFuncNotFold, MergeMaps, FuncFirstThenMap, FilterFirstThenSort, UseMinOrMaxNotSort, UseMapNotFlatMap, UseFilterNotFlatMap, AvoidOptionMethod, TransformNotMap, DuplicateKeyInMap, InefficientUseOfListSize, OnceEvaluatedStatementsInBlockReturningFunction, IntDivisionAssignedToFloat, UseFlattenNotFilterOption, UseCountNotFilterLength, UseExistsNotCountCompare, PassPartialFunctionDirectly, UnitImplicitOrdering, RegexWarning, InvariantCondition, DecomposingEmptyCollection, InvariantExtrema, UnnecessaryMethodCall, ProducesEmptyCollection, OperationAlwaysProducesZero, ModuloByOne, DivideByOne, DivideByZero, ZeroDivideBy, UseUntilNotToMinusOne, InvalidParamToRandomNextInt, UnusedForLoopIteratorValue, StringMultiplicationByNonPositive, LikelyIndexOutOfBounds, UnnecessaryReturn, InvariantReturn, UnusedParameter, InvalidStringFormat, InvalidStringConversion, UnnecessaryStringNonEmpty, UnnecessaryStringIsEmpty, PossibleLossOfPrecision, UnsafeAbs, TypeToType, EmptyStringInterpolator, UnlikelyToString, UnthrownException, SuspiciousMatches, PassingNullIntoOption, IfDoWhile, [FloatingPo