[23] default imports between explicit/implicit classes are in conflict (

#2953)

don't use the cached default import java.lang.* in implicitly declared classes.

fixes #2952

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/lookup/CompilationUnitScope.java

@@ -764,18 +764,19 @@ private MethodBinding findStaticMethod(ReferenceBinding currentType, char[] sele
  return null;
 }
 ImportBinding[] getDefaultImports() {
- // initialize the default imports if necessary... share the default java.lang.* import
- if (this.environment.root.defaultImports != null) return this.environment.root.defaultImports;
-
  if (JavaFeature.IMPLICIT_CLASSES_AND_INSTANCE_MAIN_METHODS.isSupported(this.environment.globalOptions) &&
  this.referenceContext.isSimpleCompilationUnit()) {
  ModuleBinding module = this.environment.getModule(CharOperation.concatWith(TypeConstants.JAVA_BASE, '.'));
  if (module != null) {
  ImportBinding javaBase = new ImportBinding(TypeConstants.JAVA_BASE, true, module, null);
  // No need for the java.lang.* as module java.base covers it
  return new ImportBinding[] {javaBase};
+ // this module import is not cached, there shouldn't be many files needing it.
  }
  }
+ // initialize the default imports if necessary... share the default java.lang.* import
+ if (this.environment.root.defaultImports != null) return this.environment.root.defaultImports;
+
  Binding importBinding = this.environment.getTopLevelPackage(TypeConstants.JAVA);
  if (importBinding != null)
  importBinding = ((PackageBinding) importBinding).getTypeOrPackage(TypeConstants.JAVA_LANG[1], module(), false);

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/parser/ImplicitlyDeclaredClassesTest.java

@@ -315,4 +315,35 @@ public static void main(String ... args) {
  }"""},
  "true");
  }
+ @Test
+ public void testImplicitImport() {
+ // the explicit class must be given first to trigger https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2952
+ // the test is made as negative because we can't execute the second class
+ // and we are not interested in executing the first, which cannot see the second
+ runNegativeTest(
+ new String[] {
+ "b/B.java",
+ """
+ package b;
+ import java.util.Collection;
+ public class B {
+ public static void print(Collection<?> col) {
+ System.out.print(col.size());
+ }
+ Zork zork;
+ }
+ """,
+ "X.java",
+ """
+ void main() {
+ b.B.print(Collections.emptySet());
+ }"""
+ },
+ "----------\n" +
+ "1. ERROR in b\\B.java (at line 7)\n" +
+ " Zork zork;\n" +
+ " ^^^^\n" +
+ "Zork cannot be resolved to a type\n" +
+ "----------\n");
+ }
 }