Fix a long-standing bug with type annotation paths on raw inner class…

… types

As described in [JVMS
4.7.20.2](https://docs.oracle.com/javase/specs/jvms/se21/html/jvms-4.html#jvms-4.7.20.2),
type annotations on nested types are located with `type_path_kind=1` type path
entries, which describe steps starting with the 'outermost part of the type for
which a type annotation is admissible'.

Turbine represents class types for inner classes as a flat list of 'simple
class types' corresponding to outer and inner classes. The 'canonicalization'
step normalizes type arguments, and also ensures there's exactly one entry for
each nested class and non-static containing class. The former doesn't apply to
raw types (we erase the entire type if any part of it is raw), but the latter
is important to ensure we compute the right number of type path steps for inner
classes.

PiperOrigin-RevId: 576191070

java/com/google/turbine/types/Canonicalize.java

@@ -124,9 +124,6 @@ private ClassTy canon(ClassSymbol base, ClassTy ty) {
     if (ty.sym().equals(ClassSymbol.ERROR)) {
       return ty;
     }
-    if (isRaw(ty)) {
-      return Erasure.eraseClassTy(ty);
-    }
     // if the first name is a simple name resolved inside a nested class, add explicit qualifiers
     // for the enclosing declarations
     Iterator<ClassTy.SimpleClassTy> it = ty.classes().iterator();
@@ -140,6 +137,9 @@ private ClassTy canon(ClassSymbol base, ClassTy ty) {
     while (it.hasNext()) {
       canon = canonOne(canon, it.next());
     }
+    if (isRaw(canon)) {
+      canon = Erasure.eraseClassTy(canon);
+    }
     return canon;
   }
 

javatests/com/google/turbine/lower/LowerIntegrationTest.java

@@ -41,6 +41,10 @@
 import org.junit.runners.Parameterized;
 import org.junit.runners.Parameterized.Parameters;
 
+/**
+ * A test that compiles inputs with both javac and turbine, and asserts that the output is
+ * equivalent.
+ */
 @RunWith(Parameterized.class)
 public class LowerIntegrationTest {
 
@@ -314,6 +318,9 @@ public static Iterable<Object[]> parameters() {
       "type_anno_c_array.test",
       "type_anno_cstyle_array_dims.test",
       "type_anno_hello.test",
+      "type_anno_nested.test",
+      "type_anno_nested_generic.test",
+      "type_anno_nested_raw.test",
       "type_anno_order.test",
       "type_anno_parameter_index.test",
       "type_anno_qual.test",

javatests/com/google/turbine/lower/testdata/type_anno_nested.test

@@ -0,0 +1,23 @@
+=== Annotations.java ===
+import static java.lang.annotation.ElementType.TYPE_USE;
+import java.lang.annotation.Target;
+
+@Target(TYPE_USE) @interface A {}
+@Target(TYPE_USE) @interface B {}
+@Target(TYPE_USE) @interface C {}
+
+=== Outer.java ===
+class Outer {
+
+  @A Outer . @B Middle . @C Inner f;
+  Outer . @A MiddleStatic . @B Inner g;
+  Outer . MiddleStatic . @A InnerStatic h;
+
+  class Middle {
+    class Inner {}
+  }
+  static class MiddleStatic {
+    class Inner {}
+    static class InnerStatic {}
+  }
+}

javatests/com/google/turbine/lower/testdata/type_anno_nested_generic.test

@@ -0,0 +1,21 @@
+=== Annotations.java ===
+import static java.lang.annotation.ElementType.TYPE_USE;
+import java.lang.annotation.Target;
+
+@Target(TYPE_USE) @interface A {}
+@Target(TYPE_USE) @interface B {}
+@Target(TYPE_USE) @interface C {}
+@Target(TYPE_USE) @interface D {}
+
+=== Outer.java ===
+class Outer {
+   Outer . Middle<@A Foo . @B Bar> . Inner<@D String @C []> f;
+
+  class Middle<T> {
+    class Inner<U> {}
+  }
+
+  class Foo {
+    class Bar {}
+  }
+}

javatests/com/google/turbine/lower/testdata/type_anno_nested_raw.test

@@ -0,0 +1,32 @@
+=== Annotations.java ===
+import static java.lang.annotation.ElementType.TYPE_USE;
+import java.lang.annotation.Target;
+
+@Target(TYPE_USE) @interface A {}
+@Target(TYPE_USE) @interface B {}
+@Target(TYPE_USE) @interface C {}
+
+=== Outer.java ===
+import java.util.List;
+
+class Outer {
+  static class StaticMiddle<T> {
+    class Inner<U> {}
+    static class StaticInner<U> {}
+
+    // raw types with parameterized enclosing types
+    @A Inner a;
+    @A StaticInner b;
+  }
+
+  Outer . StaticMiddle . @A Inner e;
+  Outer . StaticMiddle . @A StaticInner f;
+  Outer . StaticMiddle<@A String> . @B Inner<@C String> g;
+
+  Outer . StaticMiddle<@A List> . @B Inner<@C List> h;
+  List<Outer . StaticMiddle . @A StaticInner> i;
+
+  // javac rejects these partially raw types
+  // Outer . StaticMiddle<@A String> . @B Inner j;
+  // Outer . StaticMiddle . @B Inner<@C String> k;
+}