[libc] Add `ctype.h` locale variants (#102711)

Summary:
This patch adds all the libc ctype variants. These ignore the locale
ingormation completely, so they're pretty much just stubs. Because these
use locale information, which is system scope, we do not enable building
them outisde of full build mode.

4 files changed, 70 insertions, 0 deletions

diff --git a/libc/test/src/CMakeLists.txt b/libc/test/src/CMakeLists.txt
index 60ea7e6a90d7..ddc6a5c7f696 100644
--- a/libc/test/src/CMakeLists.txt
+++ b/libc/test/src/CMakeLists.txt
@@ -82,6 +82,7 @@ add_subdirectory(setjmp)
 add_subdirectory(signal)
 add_subdirectory(spawn)
 add_subdirectory(time)
+add_subdirectory(locale)
 
 if(${LIBC_TARGET_OS} STREQUAL "linux")
   add_subdirectory(pthread)
diff --git a/libc/test/src/locale/CMakeLists.txt b/libc/test/src/locale/CMakeLists.txt
new file mode 100644
index 000000000000..3192004db26d
--- /dev/null
+++ b/libc/test/src/locale/CMakeLists.txt
@@ -0,0 +1,25 @@
+add_custom_target(libc-locale-tests)
+
+add_libc_test(
+  locale_test
+  SUITE
+    libc-locale-tests
+  SRCS
+    locale_test.cpp
+  DEPENDS
+    libc.include.locale
+    libc.src.locale.newlocale
+    libc.src.locale.uselocale
+    libc.src.locale.freelocale
+)
+
+add_libc_test(
+  localeconv_test
+  SUITE
+    libc-locale-tests
+  SRCS
+    localeconv_test.cpp
+  DEPENDS
+    libc.include.locale
+    libc.src.locale.localeconv
+)
diff --git a/libc/test/src/locale/locale_test.cpp b/libc/test/src/locale/locale_test.cpp
new file mode 100644
index 000000000000..bc48bb851f4e
--- /dev/null
+++ b/libc/test/src/locale/locale_test.cpp
@@ -0,0 +1,27 @@
+//===-- Unittests for locale ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/locale/freelocale.h"
+#include "src/locale/newlocale.h"
+#include "src/locale/uselocale.h"
+
+#include "test/UnitTest/Test.h"
+
+#include "include/llvm-libc-macros/locale-macros.h"
+
+TEST(LlvmLibcLocale, DefaultLocale) {
+  locale_t new_locale = LIBC_NAMESPACE::newlocale(LC_ALL, "C", nullptr);
+  EXPECT_NE(new_locale, static_cast<locale_t>(nullptr));
+
+  locale_t old_locale = LIBC_NAMESPACE::uselocale(new_locale);
+  EXPECT_NE(old_locale, static_cast<locale_t>(nullptr));
+
+  LIBC_NAMESPACE::freelocale(new_locale);
+
+  LIBC_NAMESPACE::uselocale(old_locale);
+}
diff --git a/libc/test/src/locale/localeconv_test.cpp b/libc/test/src/locale/localeconv_test.cpp
new file mode 100644
index 000000000000..79264276dec3
--- /dev/null
+++ b/libc/test/src/locale/localeconv_test.cpp
@@ -0,0 +1,17 @@
+//===-- Unittests for localeconv ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "include/llvm-libc-macros/locale-macros.h"
+#include "src/locale/localeconv.h"
+
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcLocale, DefaultLocale) {
+  struct lconv *conv = LIBC_NAMESPACE::localeconv();
+  EXPECT_STREQ(conv->decimal_point, ".");
+}