1 files changed, 59 insertions, 5 deletions

diff --git a/java/com/google/devtools/build/android/desugar/Java7Compatibility.java b/java/com/google/devtools/build/android/desugar/Java7Compatibility.java
index 752227e..30de63d 100644
--- a/java/com/google/devtools/build/android/desugar/Java7Compatibility.java
+++ b/java/com/google/devtools/build/android/desugar/Java7Compatibility.java
@@ -17,6 +17,7 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
+import javax.annotation.Nullable;
 import org.objectweb.asm.AnnotationVisitor;
 import org.objectweb.asm.Attribute;
 import org.objectweb.asm.ClassReader;
@@ -27,19 +28,28 @@ import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.TypePath;
 
 /**
- * Visitor that ensures bytecode version <= 51 (Java 7) and that throws if it sees default or static
- * interface methods (i.e., non-abstract interface methods), which don't exist in Java 7.
+ * Visitor that tries to ensures bytecode version <= 51 (Java 7) and that throws if it sees default
+ * or static interface methods (i.e., non-abstract interface methods), which don't exist in Java 7.
+ * <p>The class version will 52 iff static interface method from the bootclasspath is invoked.
+ * This is mostly ensure that the generated bytecode is valid.
  */
 public class Java7Compatibility extends ClassVisitor {
 
-  private final ClassReaderFactory factory;
+  @Nullable private final ClassReaderFactory factory;
+  @Nullable private final ClassReaderFactory bootclasspathReader;
 
   private boolean isInterface;
   private String internalName;
+  private int access;
+  private String signature;
+  private String superName;
+  private String[] interfaces;
 
-  public Java7Compatibility(ClassVisitor cv, ClassReaderFactory factory) {
+  public Java7Compatibility(
+      ClassVisitor cv, ClassReaderFactory factory, ClassReaderFactory bootclasspathReader) {
     super(Opcodes.ASM6, cv);
     this.factory = factory;
+    this.bootclasspathReader = bootclasspathReader;
   }
 
   @Override
@@ -51,6 +61,10 @@ public class Java7Compatibility extends ClassVisitor {
       String superName,
       String[] interfaces) {
     internalName = name;
+    this.access = access;
+    this.signature = signature;
+    this.superName = superName;
+    this.interfaces = interfaces;
     isInterface = BitFlags.isSet(access, Opcodes.ACC_INTERFACE);
     super.visit(
         Math.min(version, Opcodes.V1_7),
@@ -83,7 +97,10 @@ public class Java7Compatibility extends ClassVisitor {
         || "<clinit>".equals(name),
         "Interface %s defines non-abstract method %s%s, which is not supported",
         internalName, name, desc);
-    MethodVisitor result = super.visitMethod(access, name, desc, signature, exceptions);
+    MethodVisitor result =
+        new UpdateBytecodeVersionIfNecessary(
+            super.visitMethod(access, name, desc, signature, exceptions));
+
     return (isInterface && "<clinit>".equals(name)) ? new InlineJacocoInit(result) : result;
   }
 
@@ -96,6 +113,42 @@ public class Java7Compatibility extends ClassVisitor {
     }
   }
 
+  /** This will rewrite class version to 52 if it sees invokestatic on an interface. */
+  private class UpdateBytecodeVersionIfNecessary extends MethodVisitor {
+
+    boolean updated = false;
+
+    public UpdateBytecodeVersionIfNecessary(MethodVisitor methodVisitor) {
+      super(Opcodes.ASM5, methodVisitor);
+    }
+
+    @Override
+    public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) {
+      if (itf && opcode == Opcodes.INVOKESTATIC) {
+        checkNotNull(bootclasspathReader);
+        checkState(
+            bootclasspathReader.isKnown(owner),
+            "%s contains invocation of static interface method that is "
+                + "not in the bootclasspath. Owner: %s, name: %s, desc: %s.",
+            Java7Compatibility.this.internalName,
+            owner,
+            name,
+            desc);
+        if (!updated) {
+          Java7Compatibility.this.cv.visit(
+              Opcodes.V1_8,
+              Java7Compatibility.this.access,
+              Java7Compatibility.this.internalName,
+              Java7Compatibility.this.signature,
+              Java7Compatibility.this.superName,
+              Java7Compatibility.this.interfaces);
+          updated = true;
+        }
+      }
+      super.visitMethodInsn(opcode, owner, name, desc, itf);
+    }
+  }
+
   private class InlineJacocoInit extends MethodVisitor {
     public InlineJacocoInit(MethodVisitor dest) {
       super(Opcodes.ASM6, dest);
@@ -106,6 +159,7 @@ public class Java7Compatibility extends ClassVisitor {
       if (opcode == Opcodes.INVOKESTATIC
           && "$jacocoInit".equals(name)
           && internalName.equals(owner)) {
+        checkNotNull(factory);
         ClassReader bytecode = checkNotNull(factory.readIfKnown(internalName),
             "Couldn't load interface %s to inline $jacocoInit()", internalName);
         InlineOneMethod copier = new InlineOneMethod("$jacocoInit", this);