Restore Proguard behavior and add minimal flag

We previously changed AAPT2 to correctly only generate keep rules for
the constructors required to inflate the different views. This cause
projects that did not have keep rules for the other constructors that
were accessed through reflection to have runtime crashes. This change
adds a flag to the link stage (--proguard-minimal-keep-rules) that
allows AAPT2 to only keep the constructors required for layout
inflation. If the flag is not present, then AAPT2 will generate less
specific keep rules than keep all constructors.

Bug: 116201243
Test: aapt2_tests
Change-Id: I8bb5cdf8446518ab153ea988e1243ca9494258c7

5 files changed, 88 insertions, 30 deletions

diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index 13c10478ba3e..20ea3cb6ffac 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -1260,7 +1260,7 @@ class Linker {
       return false;
     }
 
-    proguard::WriteKeepSet(keep_set, &fout);
+    proguard::WriteKeepSet(keep_set, &fout, options_.generate_minimal_proguard_rules);
     fout.Flush();
 
     if (fout.HadError()) {
diff --git a/tools/aapt2/cmd/Link.h b/tools/aapt2/cmd/Link.h
index e58a93ec416c..a42c0f250e3e 100644
--- a/tools/aapt2/cmd/Link.h
+++ b/tools/aapt2/cmd/Link.h
@@ -49,6 +49,7 @@ struct LinkOptions {
   Maybe<std::string> generate_proguard_rules_path;
   Maybe<std::string> generate_main_dex_proguard_rules_path;
   bool generate_conditional_proguard_rules = false;
+  bool generate_minimal_proguard_rules = false;
   bool generate_non_final_ids = false;
   std::vector<std::string> javadoc_annotations;
   Maybe<std::string> private_symbols;
@@ -119,6 +120,9 @@ class LinkCommand : public Command {
     AddOptionalSwitch("--proguard-conditional-keep-rules",
         "Generate conditional Proguard keep rules.",
         &options_.generate_conditional_proguard_rules);
+    AddOptionalSwitch("--proguard-minimal-keep-rules",
+        "Generate a minimal set of Proguard keep rules.",
+        &options_.generate_minimal_proguard_rules);
     AddOptionalSwitch("--no-auto-version", "Disables automatic style and layout SDK versioning.",
         &options_.no_auto_version);
     AddOptionalSwitch("--no-version-vectors",
diff --git a/tools/aapt2/java/ProguardRules.cpp b/tools/aapt2/java/ProguardRules.cpp
index d40795accf79..52e168ed47aa 100644
--- a/tools/aapt2/java/ProguardRules.cpp
+++ b/tools/aapt2/java/ProguardRules.cpp
@@ -384,7 +384,7 @@ bool CollectProguardRules(IAaptContext* context_, xml::XmlResource* res, KeepSet
   return true;
 }
 
-void WriteKeepSet(const KeepSet& keep_set, OutputStream* out) {
+void WriteKeepSet(const KeepSet& keep_set, OutputStream* out, bool minimal_keep) {
   Printer printer(out);
   for (const auto& entry : keep_set.manifest_class_set_) {
     for (const UsageLocation& location : entry.second) {
@@ -406,15 +406,19 @@ void WriteKeepSet(const KeepSet& keep_set, OutputStream* out) {
         printer.Print("-if class **.R$layout { int ")
             .Print(JavaClassGenerator::TransformToFieldName(location.name.entry))
             .Println("; }");
-        printer.Print("-keep class ").Print(entry.first.name).Print(" { <init>(")
-            .Print(entry.first.signature).Println("); }");
+
+        printer.Print("-keep class ").Print(entry.first.name).Print(" { <init>(");
+        printer.Print((minimal_keep) ? entry.first.signature : "...");
+        printer.Println("); }");
       }
     } else {
       for (const UsageLocation& location : entry.second) {
         printer.Print("# Referenced at ").Println(location.source.to_string());
       }
-      printer.Print("-keep class ").Print(entry.first.name).Print(" { <init>(")
-          .Print(entry.first.signature).Println("); }");
+
+      printer.Print("-keep class ").Print(entry.first.name).Print(" { <init>(");
+      printer.Print((minimal_keep) ? entry.first.signature : "...");
+      printer.Println("); }");
     }
     printer.Println();
   }
diff --git a/tools/aapt2/java/ProguardRules.h b/tools/aapt2/java/ProguardRules.h
index 01dad0b08aea..38b4860d1d61 100644
--- a/tools/aapt2/java/ProguardRules.h
+++ b/tools/aapt2/java/ProguardRules.h
@@ -70,7 +70,7 @@ class KeepSet {
   }
 
  private:
-  friend void WriteKeepSet(const KeepSet& keep_set, io::OutputStream* out);
+  friend void WriteKeepSet(const KeepSet& keep_set, io::OutputStream* out, bool minimal_keep);
 
   friend bool CollectLocations(const UsageLocation& location, const KeepSet& keep_set,
                                std::set<UsageLocation>* locations);
@@ -89,7 +89,7 @@ bool CollectProguardRules(IAaptContext* context, xml::XmlResource* res, KeepSet*
 
 bool CollectResourceReferences(IAaptContext* context, ResourceTable* table, KeepSet* keep_set);
 
-void WriteKeepSet(const KeepSet& keep_set, io::OutputStream* out);
+void WriteKeepSet(const KeepSet& keep_set, io::OutputStream* out, bool minimal_keep);
 
 bool CollectLocations(const UsageLocation& location, const KeepSet& keep_set,
                       std::set<UsageLocation>* locations);
diff --git a/tools/aapt2/java/ProguardRules_test.cpp b/tools/aapt2/java/ProguardRules_test.cpp
index 83c72d89bb62..3d93cb1dd43b 100644
--- a/tools/aapt2/java/ProguardRules_test.cpp
+++ b/tools/aapt2/java/ProguardRules_test.cpp
@@ -26,10 +26,10 @@ using ::testing::Not;
 
 namespace aapt {
 
-std::string GetKeepSetString(const proguard::KeepSet& set) {
+std::string GetKeepSetString(const proguard::KeepSet& set, bool minimal_rules) {
   std::string out;
   StringOutputStream sout(&out);
-  proguard::WriteKeepSet(set, &sout);
+  proguard::WriteKeepSet(set, &sout, minimal_rules);
   sout.Flush();
   return out;
 }
@@ -53,8 +53,17 @@ TEST(ProguardRulesTest, ManifestRuleDefaultConstructorOnly) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRulesForManifest(manifest.get(), &set, false));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarAppComponentFactory { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarBackupAgent { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarApplication { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarActivity { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarService { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarReceiver { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarProvider { <init>(); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarInstrumentation { <init>(); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarAppComponentFactory { <init>(); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarBackupAgent { <init>(); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.BarApplication { <init>(); }"));
@@ -75,8 +84,10 @@ TEST(ProguardRulesTest, FragmentNameRuleIsEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(); }"));
 }
 
@@ -89,8 +100,10 @@ TEST(ProguardRulesTest, FragmentClassRuleIsEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(); }"));
 }
 
@@ -105,8 +118,11 @@ TEST(ProguardRulesTest, FragmentNameAndClassRulesAreEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Baz { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Baz { <init>(); }"));
 }
@@ -133,7 +149,12 @@ TEST(ProguardRulesTest, NavigationFragmentNameAndClassRulesAreEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), navigation.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.package.Foo { <init>(...); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.package.Bar { <init>(...); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.base.Nested { <init>(...); }"));
+
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr("-keep class com.package.Foo { <init>(...); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.package.Bar { <init>(...); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.base.Nested { <init>(...); }"));
@@ -150,8 +171,10 @@ TEST(ProguardRulesTest, CustomViewRulesAreEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr(
       "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
 }
@@ -188,11 +211,16 @@ TEST(ProguardRulesTest, IncludedLayoutRulesAreConditional) {
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), bar_layout.get(), &set));
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), foo_layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-if class **.R$layout"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
+  EXPECT_THAT(actual, HasSubstr("int foo"));
+  EXPECT_THAT(actual, HasSubstr("int bar"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr("-if class **.R$layout"));
   EXPECT_THAT(actual, HasSubstr(
-      "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
+    "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
   EXPECT_THAT(actual, HasSubstr("int foo"));
   EXPECT_THAT(actual, HasSubstr("int bar"));
 }
@@ -209,10 +237,16 @@ TEST(ProguardRulesTest, AliasedLayoutRulesAreConditional) {
   set.AddReference({test::ParseNameOrDie("layout/bar"), {}}, layout->file.name);
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr(
+      "-keep class com.foo.Bar { <init>(...); }"));
+  EXPECT_THAT(actual, HasSubstr("-if class **.R$layout"));
+  EXPECT_THAT(actual, HasSubstr("int foo"));
+  EXPECT_THAT(actual, HasSubstr("int bar"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr(
-      "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
+    "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
   EXPECT_THAT(actual, HasSubstr("-if class **.R$layout"));
   EXPECT_THAT(actual, HasSubstr("int foo"));
   EXPECT_THAT(actual, HasSubstr("int bar"));
@@ -230,11 +264,14 @@ TEST(ProguardRulesTest, NonLayoutReferencesAreUnconditional) {
   set.AddReference({test::ParseNameOrDie("style/MyStyle"), {}}, layout->file.name);
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, Not(HasSubstr("-if")));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, Not(HasSubstr("-if")));
   EXPECT_THAT(actual, HasSubstr(
-      "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
+    "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
 }
 
 TEST(ProguardRulesTest, ViewOnClickRuleIsEmitted) {
@@ -247,10 +284,13 @@ TEST(ProguardRulesTest, ViewOnClickRuleIsEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), layout.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
-
+  std::string actual = GetKeepSetString(set,  /** minimal_rules */ false);
   EXPECT_THAT(actual, HasSubstr(
       "-keepclassmembers class * { *** bar_method(android.view.View); }"));
+
+  actual = GetKeepSetString(set,  /** minimal_rules */ true);
+  EXPECT_THAT(actual, HasSubstr(
+    "-keepclassmembers class * { *** bar_method(android.view.View); }"));
 }
 
 TEST(ProguardRulesTest, MenuRulesAreEmitted) {
@@ -267,10 +307,16 @@ TEST(ProguardRulesTest, MenuRulesAreEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), menu.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set,  /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr(
+    "-keepclassmembers class * { *** on_click(android.view.MenuItem); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Baz { <init>(...); }"));
+  EXPECT_THAT(actual, Not(HasSubstr("com.foo.Bat")));
 
+  actual = GetKeepSetString(set,  /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr(
-      "-keepclassmembers class * { *** on_click(android.view.MenuItem); }"));
+    "-keepclassmembers class * { *** on_click(android.view.MenuItem); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(android.content.Context); }"));
   EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Baz { <init>(android.content.Context); }"));
   EXPECT_THAT(actual, Not(HasSubstr("com.foo.Bat")));
@@ -287,10 +333,12 @@ TEST(ProguardRulesTest, TransitionPathMotionRulesAreEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), transition.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr(
-      "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
+    "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
 }
 
 TEST(ProguardRulesTest, TransitionRulesAreEmitted) {
@@ -304,10 +352,12 @@ TEST(ProguardRulesTest, TransitionRulesAreEmitted) {
   proguard::KeepSet set;
   ASSERT_TRUE(proguard::CollectProguardRules(context.get(), transitionSet.get(), &set));
 
-  std::string actual = GetKeepSetString(set);
+  std::string actual = GetKeepSetString(set, /** minimal_rules */ false);
+  EXPECT_THAT(actual, HasSubstr("-keep class com.foo.Bar { <init>(...); }"));
 
+  actual = GetKeepSetString(set, /** minimal_rules */ true);
   EXPECT_THAT(actual, HasSubstr(
-      "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
+    "-keep class com.foo.Bar { <init>(android.content.Context, android.util.AttributeSet); }"));
 }
 
 }  // namespace aapt