Avoid using ctype's isalpha.

In general, ctype is local-dependent, and in MSVC isalpha asserts on non-ascii characters

PiperOrigin-RevId: 606696757

src/google/protobuf/compiler/command_line_interface.cc

@@ -95,6 +95,10 @@
 #include "google/protobuf/io/io_win32.h"
 #endif
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+#include "absl/strings/ascii.h"
+#endif
+
 // Must be included last.
 #include "google/protobuf/port_def.inc"
 
@@ -130,7 +134,7 @@ static const char* kDefaultDirectDependenciesViolationMsg =
 // copy in importer.cc?
 static bool IsWindowsAbsolutePath(const std::string& text) {
 #if defined(_WIN32) || defined(__CYGWIN__)
-  return text.size() >= 3 && text[1] == ':' && isalpha(text[0]) &&
+  return text.size() >= 3 && text[1] == ':' && absl::ascii_isalpha(text[0]) &&
          (text[2] == '/' || text[2] == '\\') && text.find_last_of(':') == 1;
 #else
   return false;

src/google/protobuf/compiler/importer.cc

@@ -36,10 +36,6 @@
 #include "google/protobuf/io/tokenizer.h"
 #include "google/protobuf/io/zero_copy_stream_impl.h"
 
-#ifdef _WIN32
-#include <ctype.h>
-#endif
-
 namespace google {
 namespace protobuf {
 namespace compiler {
@@ -51,12 +47,16 @@ using google::protobuf::io::win32::access;
 using google::protobuf::io::win32::open;
 #endif
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+#include "absl/strings/ascii.h"
+#endif
+
 // Returns true if the text looks like a Windows-style absolute path, starting
 // with a drive letter.  Example:  "C:\foo".  TODO:  Share this with
 // copy in command_line_interface.cc?
 static bool IsWindowsAbsolutePath(absl::string_view text) {
 #if defined(_WIN32) || defined(__CYGWIN__)
-  return text.size() >= 3 && text[1] == ':' && isalpha(text[0]) &&
+  return text.size() >= 3 && text[1] == ':' && absl::ascii_isalpha(text[0]) &&
          (text[2] == '/' || text[2] == '\\') && text.find_last_of(':') == 1;
 #else
   return false;

src/google/protobuf/io/BUILD.bazel

@@ -177,6 +177,7 @@ cc_library(
     deps = [
         "//src/google/protobuf:arena",
         "//src/google/protobuf/stubs:lite",
+        "@com_google_absl//absl/strings",
     ],
 )
 

src/google/protobuf/io/io_win32.cc

@@ -37,6 +37,8 @@
 #include <sys/types.h>
 #include <wctype.h>
 
+#include "absl/strings/ascii.h"
+
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN 1
 #endif
@@ -64,7 +66,7 @@ struct CharTraits {
 
 template <>
 struct CharTraits<char> {
-  static bool is_alpha(char ch) { return isalpha(ch); }
+  static bool is_alpha(char ch) { return absl::ascii_isalpha(ch); }
 };
 
 template <>