[stdlib] Add Pointer(to=) and UnsafePointer(to=) constructors

mojo/stdlib/src/memory/pointer.mojo

@@ -341,6 +341,15 @@ struct Pointer[
         """
         self._value = _mlir_value
 
+    @always_inline("nodebug")
+    fn __init__(out self, *, ref [origin, address_space._value.value]to: type):
+        """Constructs a Pointer from a reference to a value.
+
+        Args:
+            to: The value to construct a pointer to.
+        """
+        self = Self(_mlir_value=__get_mvalue_as_litref(to))
+
     @staticmethod
     @always_inline("nodebug")
     fn address_of(ref [origin, address_space]value: type) -> Self:

mojo/stdlib/src/memory/unsafe_pointer.mojo

@@ -128,6 +128,15 @@ struct UnsafePointer[
         """
         self.address = value
 
+    @always_inline("nodebug")
+    fn __init__(out self, *, ref [origin, address_space._value.value]to: type):
+        """Constructs a Pointer from a reference to a value.
+
+        Args:
+            to: The value to construct a pointer to.
+        """
+        self = Self(__mlir_op.`lit.ref.to_pointer`(__get_mvalue_as_litref(to)))
+
     @always_inline
     @implicit
     fn __init__(

mojo/stdlib/test/memory/test_reference.mojo → mojo/stdlib/test/memory/test_pointer.mojo

@@ -11,7 +11,7 @@
 # limitations under the License.
 # ===----------------------------------------------------------------------=== #
 # RUN: %mojo %s
-from testing import assert_equal, assert_true
+from testing import assert_equal, assert_true, assert_not_equal
 
 
 def test_copy_reference_explicitly():
@@ -41,7 +41,13 @@ def test_str():
     assert_true(String(a_ref).startswith("0x"))
 
 
+def test_pointer_to():
+    var local = 1
+    assert_not_equal(0, Pointer(to=local)[])
+
+
 def main():
     test_copy_reference_explicitly()
     test_equality()
     test_str()
+    test_pointer_to()

mojo/stdlib/test/memory/test_unsafepointer.mojo

@@ -101,6 +101,11 @@ def test_address_of():
     _ = local
 
 
+def test_pointer_to():
+    var local = 1
+    assert_not_equal(0, UnsafePointer(to=local)[])
+
+
 def test_explicit_copy_of_pointer_address():
     var local = 1
     var ptr = UnsafePointer[Int].address_of(local)
@@ -358,6 +363,7 @@ def test_volatile_load_and_store_simd():
 
 def main():
     test_address_of()
+    test_pointer_to()
 
     test_refitem()
     test_refitem_offset()