Fix lookup of fields in interfaces

MOE_MIGRATED_REVID=136422410

4 files changed, 53 insertions, 28 deletions

diff --git a/java/com/google/turbine/binder/ConstEvaluator.java b/java/com/google/turbine/binder/ConstEvaluator.java
index 04cddcf..3a95cd4 100644
--- a/java/com/google/turbine/binder/ConstEvaluator.java
+++ b/java/com/google/turbine/binder/ConstEvaluator.java
@@ -176,19 +176,21 @@ public class ConstEvaluator {
       for (int i = 0; i < result.remaining().size() - 1; i++) {
         sym = Resolve.resolve(env, sym, result.remaining().get(i));
       }
-      field = inheritedField(env, sym, Iterables.getLast(result.remaining()));
+      field = Resolve.resolveField(env, sym, Iterables.getLast(result.remaining()));
       if (field != null) {
         return field;
       }
     }
     ClassSymbol classSymbol = owner.memberImports().singleMemberImport(simpleName);
-    field = inheritedField(env, classSymbol, simpleName);
-    if (field != null) {
-      return field;
+    if (classSymbol != null) {
+      field = Resolve.resolveField(env, classSymbol, simpleName);
+      if (field != null) {
+        return field;
+      }
     }
     Iterator<ClassSymbol> it = owner.memberImports().onDemandImports();
     while (it.hasNext()) {
-      field = inheritedField(env, it.next(), simpleName);
+      field = Resolve.resolveField(env, it.next(), simpleName);
       if (field != null) {
         return field;
       }
@@ -201,7 +203,7 @@ public class ConstEvaluator {
       Env<ClassSymbol, TypeBoundClass> env, ClassSymbol sym, String name) {
     while (sym != null) {
       TypeBoundClass info = env.get(sym);
-      FieldInfo field = inheritedField(env, sym, name);
+      FieldInfo field = Resolve.resolveField(env, sym, name);
       if (field != null) {
         return field;
       }
@@ -210,28 +212,6 @@ public class ConstEvaluator {
     return null;
   }
 
-  private static FieldInfo inheritedField(
-      Env<ClassSymbol, TypeBoundClass> env, ClassSymbol sym, String name) {
-    while (sym != null) {
-      TypeBoundClass info = env.get(sym);
-      FieldInfo field = getField(info, name);
-      if (field != null) {
-        return field;
-      }
-      sym = info.superclass();
-    }
-    return null;
-  }
-
-  private static FieldInfo getField(TypeBoundClass info, String name) {
-    for (FieldInfo f : info.fields()) {
-      if (f.name().equals(name)) {
-        return f;
-      }
-    }
-    return null;
-  }
-
   /** Casts the value to the given type. */
   static Const cast(Type ty, Const value) {
     checkNotNull(value);
diff --git a/java/com/google/turbine/binder/Resolve.java b/java/com/google/turbine/binder/Resolve.java
index 25ffe11..5f8ad31 100644
--- a/java/com/google/turbine/binder/Resolve.java
+++ b/java/com/google/turbine/binder/Resolve.java
@@ -18,6 +18,8 @@ package com.google.turbine.binder;
 
 import com.google.turbine.binder.bound.BoundClass;
 import com.google.turbine.binder.bound.HeaderBoundClass;
+import com.google.turbine.binder.bound.TypeBoundClass;
+import com.google.turbine.binder.bound.TypeBoundClass.FieldInfo;
 import com.google.turbine.binder.env.CompoundEnv;
 import com.google.turbine.binder.env.Env;
 import com.google.turbine.binder.lookup.CanonicalSymbolResolver;
@@ -90,4 +92,32 @@ public class Resolve {
       return sym;
     }
   }
+
+  /**
+   * Performs qualified type name resolution of an instance variable with the given simple name,
+   * qualified by the given symbol. The search considers members that are inherited from
+   * superclasses or interfaces.
+   */
+  public static FieldInfo resolveField(
+      Env<ClassSymbol, TypeBoundClass> env, ClassSymbol sym, String name) {
+    TypeBoundClass info = env.get(sym);
+    for (FieldInfo f : info.fields()) {
+      if (f.name().equals(name)) {
+        return f;
+      }
+    }
+    if (info.superclass() != null) {
+      FieldInfo field = resolveField(env, info.superclass(), name);
+      if (field != null) {
+        return field;
+      }
+    }
+    for (ClassSymbol i : info.interfaces()) {
+      FieldInfo field = resolveField(env, i, name);
+      if (field != null) {
+        return field;
+      }
+    }
+    return null;
+  }
 }
diff --git a/javatests/com/google/turbine/lower/LowerIntegrationTest.java b/javatests/com/google/turbine/lower/LowerIntegrationTest.java
index 9b57742..4932e69 100644
--- a/javatests/com/google/turbine/lower/LowerIntegrationTest.java
+++ b/javatests/com/google/turbine/lower/LowerIntegrationTest.java
@@ -216,6 +216,7 @@ public class LowerIntegrationTest {
       "wild2.test",
       "wild3.test",
       "const_hiding.test",
+      "interface_field.test",
     };
     List<Object[]> tests =
         ImmutableList.copyOf(testCases).stream().map(x -> new Object[] {x}).collect(toList());
diff --git a/javatests/com/google/turbine/lower/testdata/interface_field.test b/javatests/com/google/turbine/lower/testdata/interface_field.test
new file mode 100644
index 0000000..6d2053f
--- /dev/null
+++ b/javatests/com/google/turbine/lower/testdata/interface_field.test
@@ -0,0 +1,14 @@
+%%% S.java %%%
+public interface S {
+  int X = 42;
+}
+
+
+%%% A.java %%%
+public class A implements S {
+}
+
+=== B.java ===
+public class B {
+  public static final int Y = A.X;
+}