Compiler error with Java 21

[cushon]

Describe the bug

The project fails to compile at the Java 21 language level.

Reproduction

JAVA_HOME=<path to JDK 21> mvn install

Logs

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.12.1:compile (default-compile) on project named-regexp: Compilation failure: Compilation failure:
[ERROR] ./named-regexp/src/main/java/com/google/code/regexp/Matcher.java:[314,38] namedGroups() in com.google.code.regexp.Matcher cannot implement namedGroups() in java.util.regex.MatchResult
[ERROR]   return type java.util.List<java.util.Map<java.lang.String,java.lang.String>> is not compatible with java.util.Map<java.lang.String,java.lang.Integer>
[ERROR] .,/named-regexp/src/main/java/com/google/code/regexp/MatchResult.java:[44,38] namedGroups() in com.google.code.regexp.MatchResult clashes with namedGroups() in java.util.regex.MatchResult
[ERROR]   return type java.util.List<java.util.Map<java.lang.String,java.lang.String>> is not compatible with java.util.Map<java.lang.String,java.lang.Integer>

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A, please open a GitHub Discussion instead.
• The provided reproduction is a minimal reproducible of the bug.

[cushon]

The namedGroups() API was added to the JDK in JDK 20: https://bugs.openjdk.org/browse/JDK-8292872

The repro also required updating the source version to 1.8:

diff --git a/pom.xml b/pom.xml
index c88cba2..2f96e9d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -60,8 +60,8 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <maven.javadoc.failOnError>false</maven.javadoc.failOnError>
-    <maven.compiler.source>1.6</maven.compiler.source>
-    <maven.compiler.target>1.6</maven.compiler.target>
+    <maven.compiler.source>8</maven.compiler.source>
+    <maven.compiler.target>8</maven.compiler.target>
   </properties>

   <build>

[tony19]

Hmm. This library is a backport of named capture groups, which were introduced in Java 7. If you can target Java 8, why would you need to use this library? What am I missing?

If it really is needed, I suppose I could create a major release that renames namedGroups() to namedGroupsList() as an upgrade path.

[cushon]

Thanks, that is a good question! I noticed this because my employer builds third party dependencies from source, and I was testing with Java 21. We were using named-regexp as a dependency of https://github.com/contentful/contentful.java

Using java.util.regex instead of the backport works for me, I also sent a PR to update contentful: contentful/contentful.java#297

[tony19]

I decided to address the problem anyway.

Fixed in #74, released in v1.0.0.