[PATCH] D140265: [llvm][ADT] Allow returning `std::nullopt` in TypeSwitch

[Markus Böck via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG1d43966bc33a: [llvm][ADT] Allow returning `std::nullopt` in TypeSwitch (authored by zero9178).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D140265/new/

https://reviews.llvm.org/D140265

Files:
  llvm/include/llvm/ADT/TypeSwitch.h
  llvm/unittests/ADT/TypeSwitchTest.cpp


Index: llvm/unittests/ADT/TypeSwitchTest.cpp
===================================================================
--- llvm/unittests/ADT/TypeSwitchTest.cpp
+++ llvm/unittests/ADT/TypeSwitchTest.cpp
@@ -86,3 +86,31 @@
   EXPECT_EQ(0, translate(DerivedD()));
   EXPECT_EQ(-1, translate(DerivedE()));
 }
+
+TEST(TypeSwitchTest, CaseOptional) {
+  auto translate = [](auto value) {
+    return TypeSwitch<Base *, std::optional<int>>(&value)
+        .Case([](DerivedA *) { return 0; })
+        .Case([](DerivedC *) { return std::nullopt; })
+        .Default([](Base *) { return -1; });
+  };
+  EXPECT_EQ(0, translate(DerivedA()));
+  EXPECT_EQ(std::nullopt, translate(DerivedC()));
+  EXPECT_EQ(-1, translate(DerivedD()));
+  EXPECT_EQ(std::nullopt,
+            (TypeSwitch<Base *, std::optional<int>>(nullptr).Default(
+                [](Base *) { return std::nullopt; })));
+}
+
+TEST(TypeSwitchTest, CasesOptional) {
+  auto translate = [](auto value) {
+    return TypeSwitch<Base *, std::optional<int>>(&value)
+        .Case<DerivedB, DerivedC>([](auto *) { return std::nullopt; })
+        .Case([](DerivedA *) { return 0; })
+        .Default([](Base *) { return -1; });
+  };
+  EXPECT_EQ(0, translate(DerivedA()));
+  EXPECT_EQ(std::nullopt, translate(DerivedB()));
+  EXPECT_EQ(std::nullopt, translate(DerivedC()));
+  EXPECT_EQ(-1, translate(DerivedD()));
+}
Index: llvm/include/llvm/ADT/TypeSwitch.h
===================================================================
--- llvm/include/llvm/ADT/TypeSwitch.h
+++ llvm/include/llvm/ADT/TypeSwitch.h
@@ -119,7 +119,7 @@
 
     // Check to see if CaseT applies to 'value'.
     if (auto caseValue = BaseT::template castValue<CaseT>(this->value))
-      result = caseFn(caseValue);
+      result.emplace(caseFn(caseValue));
     return *this;
   }
 


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