[ADT] Introduce a static_cast_to

Author: mtrofin

llvm/include/llvm/ADT/STLExtras.h

@@ -1704,6 +1704,11 @@ auto sum_of(R &&Range, E Init = E{0}) {
   return accumulate(std::forward<R>(Range), std::move(Init));
 }
 
+/// Returns a range where each value of `R` is static_cast to `T`
+template <typename T, typename R> auto static_cast_to(R &&Range) {
+  return map_range(Range, [](const auto &V) { return static_cast<T>(V); });
+}
+
 /// Returns the product of all values in `Range` with `Init` initial value.
 /// The default initial value is 1.
 template <typename R, typename E = detail::ValueOfRange<R>>

llvm/unittests/ADT/STLExtrasTest.cpp

@@ -1669,6 +1669,13 @@ TEST(STLExtrasTest, SumOf) {
   EXPECT_EQ(sum_of(V3), 3.0f);
 }
 
+TEST(STLExtrasTest, StaticCastTo) {
+  std::vector<int32_t> R{1, 2, 3};
+  EXPECT_TRUE(all_of(R, [](auto V) { return sizeof(V) == sizeof(int32_t); }));
+  EXPECT_TRUE(all_of(static_cast_to<int64_t>(R),
+                     [](auto V) { return sizeof(V) == sizeof(int64_t); }));
+}
+
 TEST(STLExtrasTest, ProductOf) {
   EXPECT_EQ(product_of(std::vector<int>()), 1);
   EXPECT_EQ(product_of(std::vector<int>(), 0), 0);