[PATCH] D147991: [LLVM][Casting.h] Fix dyn_cast for std::unique_ptr.

[Alex Bezzubikov via Phabricator via llvm-commits]

zuban32 updated this revision to Diff 542299.
zuban32 added a comment.

- Make it reliable for unsuccessful casting cases, fix the test


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147991/new/

https://reviews.llvm.org/D147991

Files:
  llvm/include/llvm/Support/Casting.h
  llvm/unittests/Support/Casting.cpp


Index: llvm/unittests/Support/Casting.cpp
===================================================================
--- llvm/unittests/Support/Casting.cpp
+++ llvm/unittests/Support/Casting.cpp
@@ -45,6 +45,10 @@
   static bool classof(const base *B) { return true; }
 };
 
+struct derived_nocast : public base {
+  static bool classof(const base *B) { return false; }
+};
+
 template <> struct isa_impl<foo, bar> {
   static inline bool doit(const bar &Val) {
     dbgs() << "Classof: " << &Val << "\n";
@@ -212,6 +216,18 @@
   // EXPECT_EQ(F4, null_foo);
   foo *F5 = B1.daz();
   EXPECT_NE(F5, null_foo);
+
+  auto BP = std::make_unique<const bar>();
+  auto FP = dyn_cast<foo>(BP);
+  static_assert(std::is_same_v<std::unique_ptr<const foo>, decltype(FP)>,
+                "Incorrect deduced return type!");
+  EXPECT_NE(FP.get(), nullptr);
+  EXPECT_EQ(BP.get(), nullptr);
+
+  auto BP2 = std::make_unique<base>();
+  auto DP = dyn_cast<derived_nocast>(BP2);
+  EXPECT_EQ(DP.get(), nullptr);
+  EXPECT_NE(BP2.get(), nullptr);
 }
 
 // All these tests forward to dyn_cast_if_present, so they also provde an
Index: llvm/include/llvm/Support/Casting.h
===================================================================
--- llvm/include/llvm/Support/Casting.h
+++ llvm/include/llvm/Support/Casting.h
@@ -352,10 +352,10 @@
 
   static inline CastResultType castFailed() { return CastResultType(nullptr); }
 
-  static inline CastResultType doCastIfPossible(std::unique_ptr<From> &&f) {
-    if (!Self::isPossible(f))
+  static inline CastResultType doCastIfPossible(std::unique_ptr<From> &f) {
+    if (!Self::isPossible(f.get()))
       return castFailed();
-    return doCast(f);
+    return doCast(std::move(f));
   }
 };
 
@@ -665,10 +665,9 @@
 }
 
 template <typename To, typename From>
-[[nodiscard]] inline decltype(auto) dyn_cast(std::unique_ptr<From> &&Val) {
+[[nodiscard]] inline decltype(auto) dyn_cast(std::unique_ptr<From> &Val) {
   assert(detail::isPresent(Val) && "dyn_cast on a non-existent value");
-  return CastInfo<To, std::unique_ptr<From>>::doCastIfPossible(
-      std::forward<std::unique_ptr<From> &&>(Val));
+  return CastInfo<To, std::unique_ptr<From>>::doCastIfPossible(Val);
 }
 
 /// isa_and_present<X> - Functionally identical to isa, except that a null value


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