add ability to move individual core library methods

RELNOTES: None.

PiperOrigin-RevId: 186565673
GitOrigin-RevId: deb99ccfb4e6b236c21e6d425281870aa598804a
Change-Id: I56030d75aa6b3666299aa98ec961ef7078917975

3 files changed, 54 insertions, 3 deletions

diff --git a/java/com/google/devtools/build/android/desugar/CoreLibraryInvocationRewriter.java b/java/com/google/devtools/build/android/desugar/CoreLibraryInvocationRewriter.java
index e83ae41..b4bc98b 100644
--- a/java/com/google/devtools/build/android/desugar/CoreLibraryInvocationRewriter.java
+++ b/java/com/google/devtools/build/android/desugar/CoreLibraryInvocationRewriter.java
@@ -52,8 +52,18 @@ public class CoreLibraryInvocationRewriter extends ClassVisitor {
     public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) {
       Class<?> coreInterface =
           support.getCoreInterfaceRewritingTarget(opcode, owner, name, desc, itf);
+      String newOwner = support.getMoveTarget(owner, name);
 
-      if (coreInterface != null) {
+      if (newOwner != null) {
+        checkState(coreInterface == null,
+            "Can't move and use companion: %s.%s : %s", owner, name, desc);
+        if (opcode != Opcodes.INVOKESTATIC) {
+          // assuming a static method
+          desc = InterfaceDesugaring.companionDefaultMethodDescriptor(owner, desc);
+          opcode = Opcodes.INVOKESTATIC;
+        }
+        itf = false; // assuming a class
+      } else if (coreInterface != null) {
         String coreInterfaceName = coreInterface.getName().replace('.', '/');
         name =
             InterfaceDesugaring.normalizeInterfaceMethodName(
diff --git a/java/com/google/devtools/build/android/desugar/CoreLibrarySupport.java b/java/com/google/devtools/build/android/desugar/CoreLibrarySupport.java
index 9f01638..76eb346 100644
--- a/java/com/google/devtools/build/android/desugar/CoreLibrarySupport.java
+++ b/java/com/google/devtools/build/android/desugar/CoreLibrarySupport.java
@@ -16,9 +16,12 @@ package com.google.devtools.build.android.desugar;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
 
+import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import java.lang.reflect.Method;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -36,9 +39,12 @@ class CoreLibrarySupport {
   private final ImmutableList<String> renamedPrefixes;
   /** Internal names of interfaces whose default and static interface methods we'll emulate. */
   private final ImmutableList<Class<?>> emulatedInterfaces;
+  /** Map from {@code owner#name} core library members to their new owners. */
+  private final ImmutableMap<String, String> memberMoves;
 
   public CoreLibrarySupport(CoreLibraryRewriter rewriter, ClassLoader targetLoader,
-      ImmutableList<String> renamedPrefixes, ImmutableList<String> emulatedInterfaces) {
+      ImmutableList<String> renamedPrefixes, ImmutableList<String> emulatedInterfaces,
+      List<String> memberMoves) {
     this.rewriter = rewriter;
     this.targetLoader = targetLoader;
     checkArgument(
@@ -52,6 +58,23 @@ class CoreLibrarySupport {
       classBuilder.add(clazz);
     }
     this.emulatedInterfaces = classBuilder.build();
+
+    // We can call isRenamed and rename below b/c we initialized the necessary fields above
+    ImmutableMap.Builder<String, String> movesBuilder = ImmutableMap.builder();
+    Splitter splitter = Splitter.on("->").trimResults().omitEmptyStrings();
+    for (String move : memberMoves) {
+      List<String> pair = splitter.splitToList(move);
+      checkArgument(pair.size() == 2, "Doesn't split as expected: %s", move);
+      checkArgument(pair.get(0).startsWith("java/"), "Unexpected member: %s", move);
+      int sep = pair.get(0).indexOf('#');
+      checkArgument(sep > 0 && sep == pair.get(0).lastIndexOf('#'), "invalid member: %s", move);
+      checkArgument(!isRenamedCoreLibrary(pair.get(0).substring(0, sep)),
+          "Original renamed, no need to move it: %s", move);
+      checkArgument(isRenamedCoreLibrary(pair.get(1)), "Target not renamed: %s", move);
+
+      movesBuilder.put(pair.get(0), renameCoreLibrary(pair.get(1)));
+    }
+    this.memberMoves = movesBuilder.build();
   }
 
   public boolean isRenamedCoreLibrary(String internalName) {
@@ -73,6 +96,11 @@ class CoreLibrarySupport {
         : internalName;
   }
 
+  @Nullable
+  public String getMoveTarget(String owner, String name) {
+    return memberMoves.get(rewriter.unprefix(owner) + '#' + name);
+  }
+
   /**
    * Returns {@code true} for java.* classes or interfaces that are subtypes of emulated interfaces.
    * Note that implies that this method always returns {@code false} for user-written classes.
diff --git a/java/com/google/devtools/build/android/desugar/Desugar.java b/java/com/google/devtools/build/android/desugar/Desugar.java
index 58b9b88..cd55655 100644
--- a/java/com/google/devtools/build/android/desugar/Desugar.java
+++ b/java/com/google/devtools/build/android/desugar/Desugar.java
@@ -271,6 +271,18 @@ class Desugar {
     )
     public List<String> emulateCoreLibraryInterfaces;
 
+    /** Members that we will retarget to the given new owner. */
+    @Option(
+      name = "retarget_core_library_member",
+      defaultValue = "", // ignored
+      allowMultiple = true,
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {OptionEffectTag.UNKNOWN},
+      help = "Method invocations to retarget, given as \"class/Name#member->new/class/Name\".  "
+          + "The new owner is blindly assumed to exist."
+    )
+    public List<String> retargetCoreLibraryMembers;
+
     /** Set to work around b/62623509 with JaCoCo versions prior to 0.7.9. */
     // TODO(kmb): Remove when Android Studio doesn't need it anymore (see b/37116789)
     @Option(
@@ -388,7 +400,8 @@ class Desugar {
                   rewriter,
                   loader,
                   ImmutableList.copyOf(options.rewriteCoreLibraryPrefixes),
-                  ImmutableList.copyOf(options.emulateCoreLibraryInterfaces));
+                  ImmutableList.copyOf(options.emulateCoreLibraryInterfaces),
+                  options.retargetCoreLibraryMembers);
 
       desugarClassesInInput(
           inputFiles,