[libc] Fix implict cast to time_t warning

[michaelrj-google]

On some systems time_t is 32 bit, causing build errors (with -Werror)
in get_epoch which attempts to implicitly convert an int64_t to a
time_t.

Fixes:

error: implicit conversion loses integer precision: 'int64_t' (aka 'long long') to 'time_t' (aka 'int') [-Werror,-Wshorten-64-to-32]
  332 |     return mktime_internal(timeptr);
      |     ~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~

[llvmbot]

@llvm/pr-subscribers-libc

Author: Michael Jones (michaelrj-google)

Changes

On some systems time_t is 32 bit, causing build errors (with -Werror)
in get_epoch which attempts to implicitly convert an int64_t to a
time_t.

---

Full diff: https://github.com/llvm/llvm-project/pull/126947.diff

1 Files Affected:

• (modified) libc/src/time/time_utils.h (+3-1)

diff --git a/libc/src/time/time_utils.h b/libc/src/time/time_utils.h
index 324e129f6f780..68eaac8c04f11 100644
--- a/libc/src/time/time_utils.h
+++ b/libc/src/time/time_utils.h
@@ -328,7 +328,9 @@ class TMReader final {
     return BASE_YEAR + IS_NEXT_YEAR;
   }
 
-  LIBC_INLINE time_t get_epoch() const { return mktime_internal(timeptr); }
+  LIBC_INLINE time_t get_epoch() const {
+    return static_cast<time_t>(mktime_internal(timeptr));
+  }
 
   // returns the timezone offset in microwave time:
   // return (hours * 100) + minutes;

[nickdesaulniers]

mktime_internal can probably be converted to use time_t instead of int64_t.

[Prabhuk]

LGTM. I am trying a local build.