Open source

Properly use declaration-site type variance

Recipe IDorg.openrewrite.staticanalysis.DeclarationSiteTypeVariance

Artifactorg.openrewrite.recipe:rewrite-static-analysis

Currently, Java requires use-site type variance, so if someone has Function<IN, OUT> method parameter, it should rather be Function<? super IN, ? extends OUT>. Unfortunately, it is not easy to notice that ? super and ? extends is missing, so this recipe adds it where that would improve the situation.

Single recipeOpenRewriteModerne Source Available License

Try in PlatformTry this recipe in the Moderne platform. Not a user yet? You’ll get a no-setup demo environment, with nothing to install or configure.

Options

3 parameters

1 required2 optional

Parameter	Example	Type	Required
variantTypes	java.util.function.Function<IN, OUT>	List	Required
A list of well-known classes that have in/out type variance.
excludedBounds	java.lang.*	List	Optional
A list of bounds that should not receive explicit variance. Globs supported.
excludeFinalClasses	—	Boolean	Optional
If true, do not add ? extends variance to final classes. ? super variance will be added regardless of finality.

Examples

java

Parameter	Value
variantTypes	List.of("java.util.function.Function<IN, OUT>")
excludedBounds	List.of("java.lang.*")
excludeFinalClasses	true

Unchanged

interface In {}
interface Out {}

java

Before

import java.util.function.Function;
class Test {
    void test(Function<In, Out> f) {
    }
}

After

import java.util.function.Function;
class Test {
    void test(Function<? super In, ? extends Out> f) {
    }
}

Diff

@@ -3,1 +3,1 @@
import java.util.function.Function;
class Test {
-   void test(Function<In, Out> f) {
+   void test(Function<? super In, ? extends Out> f) {
    }

Usage

Run this recipe

You will need to have configured the Moderne CLI on your machine before you can run the following command.

shell

mod run . --recipe DeclarationSiteTypeVariance --recipe-option "variantTypes=java.util.function.Function<IN, OUT>" --recipe-option "excludedBounds=java.lang.*"

If the recipe is not available locally, then you can install it using:

mod config recipes jar install org.openrewrite.recipe:rewrite-static-analysis:2.37.0

Data tables

Source files that had results

org.openrewrite.table.SourcesFileResults

Source files that were modified by the recipe run.

Column	Description
Source path before the run	The source path of the file before the run. null when a source file was created during the run.
Source path after the run	A recipe may modify the source path. This is the path after the run. null when a source file was deleted during the run.
Parent of the recipe that made changes	In a hierarchical recipe, the parent of the recipe that made a change. Empty if this is the root of a hierarchy or if the recipe is not hierarchical at all.
Recipe that made changes	The specific recipe that made a change.
Estimated time saving	An estimated effort that a developer to fix manually instead of using this recipe, in unit of seconds.
Cycle	The recipe cycle in which the change was made.

Source files that had search results

org.openrewrite.table.SearchResults

Search results that were found during the recipe run.

Column	Description
Source path of search result before the run	The source path of the file with the search result markers present.
Source path of search result after run the run	A recipe may modify the source path. This is the path after the run. null when a source file was deleted during the run.
Result	The trimmed printed tree of the LST element that the marker is attached to.
Description	The content of the description of the marker.
Recipe that added the search marker	The specific recipe that added the Search marker.

Source files that errored on a recipe

org.openrewrite.table.SourcesFileErrors

The details of all errors produced by a recipe run.

Column	Description
Source path	The file that failed to parse.
Recipe that made changes	The specific recipe that made a change.
Stack trace	The stack trace of the failure.

Recipe performance

org.openrewrite.table.RecipeRunStats

Statistics used in analyzing the performance of recipes.

Column	Description
The recipe	The recipe whose stats are being measured both individually and cumulatively.
Source file count	The number of source files the recipe ran over.
Source file changed count	The number of source files which were changed in the recipe run. Includes files created, deleted, and edited.
Cumulative scanning time (ns)	The total time spent across the scanning phase of this recipe.
Max scanning time (ns)	The max time scanning any one source file.
Cumulative edit time (ns)	The total time spent across the editing phase of this recipe.
Max edit time (ns)	The max time editing any one source file.