Add -proc:full whenever we run under Java 22 or newer (#660)

This fixes some warnings when compiling sources with JDK22 while
targeting older compilers.

Author: ascopes

java-compiler-testing/src/main/java/io/github/ascopes/jct/compilers/impl/JavacJctFlagBuilderImpl.java

@@ -93,9 +93,11 @@ public JctFlagBuilder compilationMode(CompilationMode compilationMode) {
         break;
 
       default:
-        // In Java 22, the default is to disable all annotation processing by default.
-        // Prior to Java 22, the default was to enable all annotation processing by default.
-        craftedFlags.add(PROC_FULL);
+        if (Runtime.version().feature() >= 22) {
+          // In Java 22, the default is to disable all annotation processing by default
+          // Prior to Java 22, the default was to enable all annotation processing by default.
+          craftedFlags.add(PROC_FULL);
+        }
         break;
     }
 

java-compiler-testing/src/test/java/io/github/ascopes/jct/tests/unit/compilers/impl/JavacJctFlagBuilderImplTest.java

@@ -19,6 +19,7 @@
 import static io.github.ascopes.jct.tests.helpers.Fixtures.someRelease;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assumptions.assumeThat;
 
 import io.github.ascopes.jct.compilers.CompilationMode;
 import io.github.ascopes.jct.compilers.DebuggingInfo;
@@ -211,16 +212,38 @@ void annotationProcessingOnlyAddsProcOnly() {
       assertThat(flagBuilder.build()).containsExactly("-proc:only");
     }
 
-    @DisplayName(".compilationMode(COMPILATION_AND_ANNOTATION_PROCESSING) adds -proc:full")
+    @DisplayName(".compilationMode(COMPILATION_AND_ANNOTATION_PROCESSING) adds -proc:full (JDK22)")
     @Test
-    void compilationAndAnnotationProcessingAddsProcAll() {
+    void compilationAndAnnotationProcessingAddsProcFullOnJdk22() {
+      // Given
+      assumeThat(Runtime.version().feature())
+          .as("JDK version")
+          .withFailMessage("this test only works on JDK 22 and newer")
+          .isGreaterThanOrEqualTo(22);
+
       // When
       flagBuilder.compilationMode(CompilationMode.COMPILATION_AND_ANNOTATION_PROCESSING);
 
       // Then
       assertThat(flagBuilder.build()).containsExactly("-proc:full");
     }
 
+    @DisplayName(".compilationMode(COMPILATION_AND_ANNOTATION_PROCESSING) adds nothing (<JDK22)")
+    @Test
+    void compilationAndAnnotationProcessingAddsNothingBeforeJdk22() {
+      // Given
+      assumeThat(Runtime.version().feature())
+          .as("JDK version")
+          .withFailMessage("this test only works on JDK 21 and older")
+          .isLessThan(22);
+
+      // When
+      flagBuilder.compilationMode(CompilationMode.COMPILATION_AND_ANNOTATION_PROCESSING);
+
+      // Then
+      assertThat(flagBuilder.build()).isEmpty();
+    }
+
     @DisplayName(".compilationMode(...) returns the flag builder")
     @EnumSource(CompilationMode.class)
     @ParameterizedTest(name = "for compilationMode = {0}")