update to use GrailsExtension parameter name flag

Author: jdaugherty

grails-doc/src/en/guide/introduction/whatsNew.adoc

@@ -32,5 +32,7 @@ Notable new features are included below.
 Grails 8 continues the move toward method-based TagLib handlers while preserving compatibility with existing closure-based tags.
 Method-defined tags now bind named attributes more predictably, exclude inherited framework and `Object` methods from tag dispatch, and preserve real namespace property getters.
 
+The Grails Gradle extension now defaults `preserveParameterNames` to `true`, so application Groovy compilation preserves method parameter names for features such as typed method TagLib arguments.
+
 Tag library unit tests also clean up and rebuild TagLib metadata automatically between features.
 Tests that use `TagLibUnitTest` no longer need to manage `purgeTagLibMetaClass`, and specs that mock additional tag libraries continue to work across feature methods.

grails-doc/src/en/guide/upgrading/upgrading80x.adoc

@@ -677,7 +677,35 @@ class MyTagLibSpec extends Specification implements TagLibUnitTest<MyTagLib> {
 }
 ----
 
-==== 21. Known Plugin Incompatibilities
+==== 21. Grails Gradle Extension Preserves Parameter Names By Default
+
+In Grails 8, the Grails Gradle extension defaults `preserveParameterNames` to `true`.
+This configures Groovy compilation to retain method and constructor parameter names in generated class files.
+
+This behavior supports framework features that bind by parameter name, including method-based TagLib handlers annotated with `@grails.gsp.Tag`:
+
+[source,groovy]
+----
+import grails.gsp.Tag
+
+class DemoTagLib {
+    @Tag
+    def greeting(String name) {
+        out << "Hello, ${name}!"
+    }
+}
+----
+
+If you need the previous Groovy compiler behavior, disable it in `build.gradle`:
+
+[source,groovy]
+----
+grails {
+    preserveParameterNames = false
+}
+----
+
+==== 22. Known Plugin Incompatibilities
 
 Some third-party plugins have not yet been updated for Spring Boot 4 / Spring Framework 7 compatibility.
 The following are known blockers at this time:
@@ -690,7 +718,7 @@ Applications using `grails-sitemesh3` should remain on the `grails-layout` plugi
 
 Check the https://github.com/apache/grails-core/issues[Grails issue tracker] for the latest status of plugin compatibility.
 
-===== 22. Custom JSON View Converters
+===== 23. Custom JSON View Converters
 
 JSON views now use Groovy's `groovy.json.JsonGenerator` implementation instead of the previous Grails-specific
 JSON generator infrastructure.

grails-gradle/plugins/src/main/groovy/org/grails/gradle/plugin/core/GrailsGradlePlugin.groovy

@@ -58,7 +58,6 @@ import org.gradle.api.tasks.SourceSetOutput
 import org.gradle.api.tasks.TaskContainer
 import org.gradle.api.tasks.TaskProvider
 import org.gradle.api.tasks.compile.GroovyCompile
-import org.gradle.api.tasks.compile.JavaCompile
 import org.gradle.api.tasks.testing.Test
 import org.gradle.jvm.toolchain.JavaToolchainService
 import org.gradle.language.jvm.tasks.ProcessResources
@@ -190,8 +189,6 @@ class GrailsGradlePlugin implements Plugin<Project> {
 
     private void configureGroovyCompiler(Project project) {
         project.tasks.withType(GroovyCompile).configureEach { GroovyCompile c ->
-            c.groovyOptions.parameters = true
-
             // Use a task-specific config file to avoid overlapping outputs when multiple
             // GroovyCompile tasks exist in the same project (e.g. compileGroovy, compileTestGroovy).
             Provider<RegularFile> groovyCompilerConfigFile = project.layout.buildDirectory.file("grailsGroovyCompilerConfig-${c.name}.groovy")
@@ -233,12 +230,6 @@ class GrailsGradlePlugin implements Plugin<Project> {
             }
         }
 
-        project.tasks.withType(JavaCompile).configureEach { JavaCompile c ->
-            if (!c.options.compilerArgs.contains('-parameters')) {
-                c.options.compilerArgs.add('-parameters')
-            }
-        }
-
         // Configure indy and log status after evaluation so user's grails { } block has been applied
         GrailsExtension grailsExtension = project.extensions.findByType(GrailsExtension)
         project.afterEvaluate {
@@ -249,6 +240,7 @@ class GrailsGradlePlugin implements Plugin<Project> {
                 c.groovyOptions.optimizationOptions.indy = indyEnabled
 
                 if (preserveParameterNames != null) {
+                    logger.info("Grails: Configuring Groovy compilation to preserve parameter names: {}", preserveParameterNames)
                     c.groovyOptions.parameters = preserveParameterNames
                 }
             }