[clang] [clang-tools-extra] [libc] [libc][c11] implement ctime (PR #107285)

[Зишан Мирза via cfe-commits]

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@@ -0,0 +1,25 @@
+//===-- Implementation of ctime_r function --------------------------------===//
+//
+// 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/time/ctime_r.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+using LIBC_NAMESPACE::time_utils::TimeConstants;
+
+LLVM_LIBC_FUNCTION(char *, ctime_r, (const time_t *t_ptr, char *buffer)) {
+  if (t_ptr > 2147483647) {
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zimirza wrote:

I have only found these references outside of tests:

```
./mlir/lib/Dialect/GPU/TransformOps/Utils.cpp:244:  static constexpr int maxTotalGriddim = 2147483647;
./mlir/lib/Dialect/GPU/TransformOps/Utils.cpp:245:  static constexpr int maxGriddimx = 2147483647;
```

It should really be in `time_utils.h`. I can add it to `TimeConstants` struct.

https://github.com/llvm/llvm-project/pull/107285