From 89dea017ae18c6fcc6dda06a9accffc32c7e61cc Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Tue, 26 Mar 2019 20:56:36 +0000
Subject: [PATCH] Bug 1539016 part 2.  Teach MOZ_CAN_RUN_SCRIPT analysis about
 conditional operators.  r=andi

Differential Revision: https://phabricator.services.mozilla.com/D24839

--HG--
extra : moz-landing-system : lando
---
 build/clang-plugin/CanRunScriptChecker.cpp    | 14 +++-
 build/clang-plugin/tests/TestCanRunScript.cpp | 77 +++++++++++++++++++
 2 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/build/clang-plugin/CanRunScriptChecker.cpp b/build/clang-plugin/CanRunScriptChecker.cpp
index 939eff199f05..35243dfe372d 100644
--- a/build/clang-plugin/CanRunScriptChecker.cpp
+++ b/build/clang-plugin/CanRunScriptChecker.cpp
@@ -133,6 +133,18 @@ void CanRunScriptChecker::registerMatchers(MatchFinder *AstMatcher) {
               // just use ignoreTrivials to strip off the cast.
               ignoreTrivials(KnownLiveBase))));
 
+  auto KnownLive = anyOf(
+      // Anything above, of course.
+      KnownLiveSimple,
+      // Conditional operators where both arms are live.
+      conditionalOperator(
+          hasFalseExpression(ignoreTrivials(KnownLiveSimple)),
+          hasTrueExpression(ignoreTrivials(KnownLiveSimple)))
+      // We're not handling cases like a dereference of a conditional operator,
+      // mostly because handling a dereference in general is so ugly.  I
+      // _really_ wish I could just write a recursive matcher here easily.
+      );
+
   auto InvalidArg =
       ignoreTrivialsConditional(
         // We want to consider things if there is anything refcounted involved,
@@ -146,7 +158,7 @@ void CanRunScriptChecker::registerMatchers(MatchFinder *AstMatcher) {
         // We want to find any expression,
         expr(
           // which is not known live,
-          unless(KnownLiveSimple),
+          unless(KnownLive),
           // and which is not a default arg with value nullptr, since those are
           // always safe,
           unless(cxxDefaultArgExpr(isNullDefaultArg())),
diff --git a/build/clang-plugin/tests/TestCanRunScript.cpp b/build/clang-plugin/tests/TestCanRunScript.cpp
index b61bf501c95c..6f4462846d1c 100644
--- a/build/clang-plugin/tests/TestCanRunScript.cpp
+++ b/build/clang-plugin/tests/TestCanRunScript.cpp
@@ -444,6 +444,7 @@ struct DisallowRefPtrTArrayElement {
 
 struct AllowConstexprMembers {
   static constexpr RefCountedBase* mRefCounted = nullptr;
+  static constexpr RefCountedBase* mRefCounted2 = nullptr;
   MOZ_CAN_RUN_SCRIPT void foo() {
     mRefCounted->method_test();
   }
@@ -466,3 +467,79 @@ MOZ_CAN_RUN_SCRIPT void test_constexpr_2() {
 MOZ_CAN_RUN_SCRIPT void test_constexpr_3() {
   test_ref(*AllowConstexprMembers::mRefCounted);
 }
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_1(RefCountedBase* arg1, RefCountedBase* arg2) {
+  (arg1 ? arg1 : arg2)->method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_2(RefCountedBase* arg1, RefCountedBase* arg2) {
+  test2(arg1 ? arg1 : arg2);
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_3(RefCountedBase* arg1, RefCountedBase& arg2) {
+  (arg1 ? *arg1 : arg2).method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_4(RefCountedBase* arg1, RefCountedBase& arg2) {
+  test_ref(arg1 ? *arg1 : arg2);
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_5(RefCountedBase* arg) {
+  RefPtr<RefCountedBase> local = new RefCountedBase();
+  (arg ? arg : local.get())->method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_6(RefCountedBase* arg) {
+  RefPtr<RefCountedBase> local = new RefCountedBase();
+  test2(arg ? arg : local.get());
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_7(RefCountedBase* arg) {
+  RefPtr<RefCountedBase> local = new RefCountedBase();
+  (arg ? *arg : *local).method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_8(RefCountedBase* arg) {
+  RefPtr<RefCountedBase> local = new RefCountedBase();
+  test_ref(arg ? *arg : *local);
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_9(RefCountedBase* arg) {
+  (arg ? arg : AllowConstexprMembers::mRefCounted)->method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_10(RefCountedBase* arg) {
+  test2(arg ? arg : AllowConstexprMembers::mRefCounted);
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_11(RefCountedBase* arg) {
+  (arg ? *arg : *AllowConstexprMembers::mRefCounted).method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_12(RefCountedBase* arg) {
+  test_ref(arg ? *arg : *AllowConstexprMembers::mRefCounted);
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_13(bool arg) {
+  (arg ?
+   AllowConstexprMembers::mRefCounted :
+   AllowConstexprMembers::mRefCounted2)->method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_14(bool arg) {
+  test2(arg ?
+	AllowConstexprMembers::mRefCounted :
+	AllowConstexprMembers::mRefCounted2);
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_15(bool arg) {
+  (arg ?
+   *AllowConstexprMembers::mRefCounted :
+   *AllowConstexprMembers::mRefCounted2).method_test();
+}
+
+MOZ_CAN_RUN_SCRIPT void test_ternary_16(bool arg) {
+  test_ref(arg ?
+	   *AllowConstexprMembers::mRefCounted :
+	   *AllowConstexprMembers::mRefCounted2);
+}