Replace preprocessor macros with `ToHost` from endian

PiperOrigin-RevId: 656475785

conformance/BUILD.bazel

@@ -143,6 +143,7 @@ cc_library(
         ":conformance_cc_proto",
         "//src/google/protobuf",
         "//src/google/protobuf:descriptor_legacy",
+        "//src/google/protobuf:endian",
         "//src/google/protobuf:protobuf_lite",
         "//src/google/protobuf/util:differencer",
         "//src/google/protobuf/util:json_util",

src/google/protobuf/BUILD.bazel

@@ -342,7 +342,7 @@ cc_library(
         "//src/google/protobuf:__subpackages__",
     ],
     deps = [
-        "//src/google/protobuf:port",
+        ":port",
         "//src/google/protobuf/stubs:lite",
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/log:absl_check",
@@ -479,6 +479,7 @@ cc_library(
         "repeated_ptr_field.cc",
         "wire_format_lite.cc",
     ],
+    # TODO Fix ODR violations across BUILD.bazel files.
     hdrs = [
         "any.h",
         "arena.h",
@@ -527,6 +528,7 @@ cc_library(
         ":arena_align",
         ":arena_allocation_policy",
         ":arena_cleanup",
+        ":endian",
         ":internal_visibility",
         ":port",
         ":string_block",
@@ -2066,3 +2068,17 @@ filegroup(
     ],
     visibility = ["//pkg:__pkg__"],
 )
+
+cc_library(
+    name = "endian",
+    hdrs = ["endian.h"],
+    strip_include_prefix = "/src",
+    visibility = [
+        "//conformance:__subpackages__",
+        "//src/google/protobuf:__subpackages__",
+    ],
+    deps = [
+        ":port",
+        "@com_google_absl//absl/base:config",
+    ],
+)

src/google/protobuf/io/BUILD.bazel

@@ -27,6 +27,7 @@ cc_library(
     deps = [
         ":io_win32",
         "//src/google/protobuf:arena",
+        "//src/google/protobuf:endian",
         "//src/google/protobuf:port",
         "//src/google/protobuf/stubs:lite",
         "@com_google_absl//absl/base",

src/google/protobuf/io/coded_stream.h

@@ -111,9 +111,9 @@
 #include "absl/numeric/bits.h"
 #include "absl/strings/cord.h"
 #include "absl/strings/string_view.h"
+#include "google/protobuf/endian.h"
 #include "google/protobuf/port.h"
 
-
 // Must be included last.
 #include "google/protobuf/port_def.inc"
 
@@ -1324,37 +1324,16 @@ inline bool CodedInputStream::ReadVarintSizeAsInt(int* value) {
 // static
 inline const uint8_t* CodedInputStream::ReadLittleEndian32FromArray(
     const uint8_t* buffer, uint32_t* value) {
-#if defined(ABSL_IS_LITTLE_ENDIAN) && \
-    !defined(PROTOBUF_DISABLE_LITTLE_ENDIAN_OPT_FOR_TEST)
   memcpy(value, buffer, sizeof(*value));
+  *value = google::protobuf::internal::little_endian::ToHost(*value);
   return buffer + sizeof(*value);
-#else
-  *value = (static_cast<uint32_t>(buffer[0])) |
-           (static_cast<uint32_t>(buffer[1]) << 8) |
-           (static_cast<uint32_t>(buffer[2]) << 16) |
-           (static_cast<uint32_t>(buffer[3]) << 24);
-  return buffer + sizeof(*value);
-#endif
 }
 // static
 inline const uint8_t* CodedInputStream::ReadLittleEndian64FromArray(
     const uint8_t* buffer, uint64_t* value) {
-#if defined(ABSL_IS_LITTLE_ENDIAN) && \
-    !defined(PROTOBUF_DISABLE_LITTLE_ENDIAN_OPT_FOR_TEST)
   memcpy(value, buffer, sizeof(*value));
+  *value = google::protobuf::internal::little_endian::ToHost(*value);
   return buffer + sizeof(*value);
-#else
-  uint32_t part0 = (static_cast<uint32_t>(buffer[0])) |
-                   (static_cast<uint32_t>(buffer[1]) << 8) |
-                   (static_cast<uint32_t>(buffer[2]) << 16) |
-                   (static_cast<uint32_t>(buffer[3]) << 24);
-  uint32_t part1 = (static_cast<uint32_t>(buffer[4])) |
-                   (static_cast<uint32_t>(buffer[5]) << 8) |
-                   (static_cast<uint32_t>(buffer[6]) << 16) |
-                   (static_cast<uint32_t>(buffer[7]) << 24);
-  *value = static_cast<uint64_t>(part0) | (static_cast<uint64_t>(part1) << 32);
-  return buffer + sizeof(*value);
-#endif
 }
 
 inline bool CodedInputStream::ReadLittleEndian32(uint32_t* value) {