[libc][NFC] Cleanup time.h #122027

michaelrj-google · 2025-01-08T00:22:12Z

While working on strftime I noticed some constants were being defined in
unexpected places. One thing led to another, and I ended up doing a
major cleanup of the time functions.

What's included:
All uses of <time.h> in /src and /test removed (except for LibcTest.cpp)
The various time constants have been moved to time_constants.h, and the
time_constants namespace.
struct tm gets its own type indirection header now.

While working on strftime I noticed some constants were being defined in unexpected places. One thing led to another, and I ended up doing a major cleanup of the time functions. What's included: All uses of <time.h> in /src and /test removed (except for LibcTest.cpp) The various time constants have been moved to time_constants.h, and the `time_constants` namespace. struct tm gets its own type indirection header now.

llvmbot · 2025-01-08T00:22:46Z

@llvm/pr-subscribers-libc

Author: Michael Jones (michaelrj-google)

Changes

While working on strftime I noticed some constants were being defined in
unexpected places. One thing led to another, and I ended up doing a
major cleanup of the time functions.

What's included:
All uses of <time.h> in /src and /test removed (except for LibcTest.cpp)
The various time constants have been moved to time_constants.h, and the
time_constants namespace.
struct tm gets its own type indirection header now.

Patch is 87.03 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/122027.diff

32 Files Affected:

(modified) libc/hdr/types/CMakeLists.txt (+8)
(added) libc/hdr/types/struct_tm.h (+21)
(modified) libc/src/pthread/pthread_condattr_init.cpp (+1-1)
(modified) libc/src/pthread/pthread_condattr_setclock.cpp (+1-1)
(modified) libc/src/time/CMakeLists.txt (+25)
(modified) libc/src/time/asctime.cpp (+3-4)
(modified) libc/src/time/asctime.h (+1-1)
(modified) libc/src/time/asctime_r.cpp (+3-3)
(modified) libc/src/time/asctime_r.h (+1-1)
(modified) libc/src/time/ctime.cpp (+2-4)
(modified) libc/src/time/ctime_r.cpp (+1-3)
(modified) libc/src/time/difftime.h (+1-1)
(modified) libc/src/time/gmtime.h (+2-1)
(modified) libc/src/time/gmtime_r.h (+2-1)
(modified) libc/src/time/mktime.cpp (+14-19)
(modified) libc/src/time/mktime.h (+2-1)
(added) libc/src/time/time_constants.h (+104)
(modified) libc/src/time/time_utils.cpp (+25-27)
(modified) libc/src/time/time_utils.h (+12-81)
(modified) libc/test/src/time/CMakeLists.txt (+23-2)
(modified) libc/test/src/time/TmHelper.h (+4-6)
(modified) libc/test/src/time/TmMatcher.h (+1-2)
(modified) libc/test/src/time/asctime_r_test.cpp (+3-5)
(modified) libc/test/src/time/clock_gettime_test.cpp (+3-2)
(modified) libc/test/src/time/clock_test.cpp (+1-2)
(modified) libc/test/src/time/ctime_r_test.cpp (+5-7)
(modified) libc/test/src/time/difftime_test.cpp (+2-5)
(modified) libc/test/src/time/gettimeofday_test.cpp (+1-2)
(modified) libc/test/src/time/gmtime_r_test.cpp (+23-23)
(modified) libc/test/src/time/gmtime_test.cpp (+202-181)
(modified) libc/test/src/time/mktime_test.cpp (+278-160)
(modified) libc/test/src/time/nanosleep_test.cpp (+1-2)

diff --git a/libc/hdr/types/CMakeLists.txt b/libc/hdr/types/CMakeLists.txt
index 5156b58ee11af7..1674de14201524 100644
--- a/libc/hdr/types/CMakeLists.txt
+++ b/libc/hdr/types/CMakeLists.txt
@@ -85,6 +85,14 @@ add_proxy_header_library(
     libc.include.llvm-libc-types.struct_timespec
 )
 
+add_proxy_header_library(
+  struct_tm
+  HDRS
+    struct_tm.h
+  FULL_BUILD_DEPENDS
+    libc.include.llvm-libc-types.struct_tm
+)
+
 add_proxy_header_library(
   size_t
   HDRS
diff --git a/libc/hdr/types/struct_tm.h b/libc/hdr/types/struct_tm.h
new file mode 100644
index 00000000000000..96c23e2ce054a2
--- /dev/null
+++ b/libc/hdr/types/struct_tm.h
@@ -0,0 +1,21 @@
+//===-- Proxy for struct tm  ----------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_LIBC_HDR_TYPES_STRUCT_TM_H
+#define LLVM_LIBC_HDR_TYPES_STRUCT_TM_H
+
+#ifdef LIBC_FULL_BUILD
+
+#include "include/llvm-libc-types/struct_tm.h"
+
+#else
+
+#include <time.h>
+
+#endif // LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_TYPES_STRUCT_TM_H
diff --git a/libc/src/pthread/pthread_condattr_init.cpp b/libc/src/pthread/pthread_condattr_init.cpp
index 12005b8a9d30fe..89e1dd7bf61d02 100644
--- a/libc/src/pthread/pthread_condattr_init.cpp
+++ b/libc/src/pthread/pthread_condattr_init.cpp
@@ -11,8 +11,8 @@
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
 
+#include "hdr/time_macros.h"
 #include <pthread.h> // pthread_condattr_t, PTHREAD_PROCESS_PRIVATE
-#include <time.h>    // CLOCK_REALTIME
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/pthread/pthread_condattr_setclock.cpp b/libc/src/pthread/pthread_condattr_setclock.cpp
index 37fbd6b27143dd..c294d47c2ef631 100644
--- a/libc/src/pthread/pthread_condattr_setclock.cpp
+++ b/libc/src/pthread/pthread_condattr_setclock.cpp
@@ -12,9 +12,9 @@
 #include "src/__support/macros/config.h"
 #include "src/errno/libc_errno.h"
 
+#include "hdr/time_macros.h"
 #include <pthread.h>   // pthread_condattr_t
 #include <sys/types.h> // clockid_t
-#include <time.h>      // CLOCK_MONOTONIC, CLOCK_REALTIME
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/CMakeLists.txt b/libc/src/time/CMakeLists.txt
index ae835dcc742742..200ddf61d92789 100644
--- a/libc/src/time/CMakeLists.txt
+++ b/libc/src/time/CMakeLists.txt
@@ -2,6 +2,17 @@ if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
 endif()
 
+add_header_library(
+  time_constants
+  HDRS
+    time_constants.h
+  DEPENDS
+    libc.include.time
+    libc.src.__support.CPP.array
+    libc.src.__support.CPP.string_view
+    libc.hdr.types.time_t
+)
+
 add_object_library(
   time_utils
   SRCS
@@ -12,6 +23,10 @@ add_object_library(
     libc.include.time
     libc.src.__support.CPP.limits
     libc.src.errno.errno
+    .time_constants
+    libc.hdr.types.time_t
+    libc.hdr.types.size_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -23,6 +38,7 @@ add_entrypoint_object(
   DEPENDS
     .time_utils
     libc.include.time
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -34,6 +50,7 @@ add_entrypoint_object(
   DEPENDS
     .time_utils
     libc.include.time
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -68,6 +85,7 @@ add_entrypoint_object(
     difftime.h
   DEPENDS
     libc.include.time
+    libc.hdr.types.time_t
 )
 
 add_entrypoint_object(
@@ -79,6 +97,8 @@ add_entrypoint_object(
   DEPENDS
     .time_utils
     libc.include.time
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -90,6 +110,8 @@ add_entrypoint_object(
   DEPENDS
     .time_utils
     libc.include.time
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -102,6 +124,8 @@ add_entrypoint_object(
     .time_utils
     libc.include.time
     libc.src.errno.errno
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -115,6 +139,7 @@ add_entrypoint_object(
     libc.hdr.types.time_t
     libc.src.__support.time.clock_gettime
     libc.src.errno.errno
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
diff --git a/libc/src/time/asctime.cpp b/libc/src/time/asctime.cpp
index d6fbe7316ced0d..b8a7c1c601c8ae 100644
--- a/libc/src/time/asctime.cpp
+++ b/libc/src/time/asctime.cpp
@@ -13,11 +13,10 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
-using LIBC_NAMESPACE::time_utils::TimeConstants;
-
 LLVM_LIBC_FUNCTION(char *, asctime, (const struct tm *timeptr)) {
-  static char buffer[TimeConstants::ASCTIME_BUFFER_SIZE];
-  return time_utils::asctime(timeptr, buffer, TimeConstants::ASCTIME_MAX_BYTES);
+  static char buffer[time_constants::ASCTIME_BUFFER_SIZE];
+  return time_utils::asctime(timeptr, buffer,
+                             time_constants::ASCTIME_MAX_BYTES);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/asctime.h b/libc/src/time/asctime.h
index 623e6dff60c334..37325e75b829dc 100644
--- a/libc/src/time/asctime.h
+++ b/libc/src/time/asctime.h
@@ -9,8 +9,8 @@
 #ifndef LLVM_LIBC_SRC_TIME_ASCTIME_H
 #define LLVM_LIBC_SRC_TIME_ASCTIME_H
 
+#include "hdr/types/struct_tm.h"
 #include "src/__support/macros/config.h"
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/asctime_r.cpp b/libc/src/time/asctime_r.cpp
index caa22f1cd77833..bf53bfdf2f8c2f 100644
--- a/libc/src/time/asctime_r.cpp
+++ b/libc/src/time/asctime_r.cpp
@@ -9,15 +9,15 @@
 #include "src/time/asctime_r.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/time/time_constants.h"
 #include "src/time/time_utils.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
-using LIBC_NAMESPACE::time_utils::TimeConstants;
-
 LLVM_LIBC_FUNCTION(char *, asctime_r,
                    (const struct tm *timeptr, char *buffer)) {
-  return time_utils::asctime(timeptr, buffer, TimeConstants::ASCTIME_MAX_BYTES);
+  return time_utils::asctime(timeptr, buffer,
+                             time_constants::ASCTIME_MAX_BYTES);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/asctime_r.h b/libc/src/time/asctime_r.h
index 328b7dff19c2e9..65a6b84ca38f60 100644
--- a/libc/src/time/asctime_r.h
+++ b/libc/src/time/asctime_r.h
@@ -9,8 +9,8 @@
 #ifndef LLVM_LIBC_SRC_TIME_ASCTIME_R_H
 #define LLVM_LIBC_SRC_TIME_ASCTIME_R_H
 
+#include "hdr/types/struct_tm.h"
 #include "src/__support/macros/config.h"
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/ctime.cpp b/libc/src/time/ctime.cpp
index 8adae9be73809a..49a33becf5d8e4 100644
--- a/libc/src/time/ctime.cpp
+++ b/libc/src/time/ctime.cpp
@@ -14,15 +14,13 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
-using LIBC_NAMESPACE::time_utils::TimeConstants;
-
 LLVM_LIBC_FUNCTION(char *, ctime, (const time_t *t_ptr)) {
   if (t_ptr == nullptr || *t_ptr > cpp::numeric_limits<int32_t>::max()) {
     return nullptr;
   }
-  static char buffer[TimeConstants::ASCTIME_BUFFER_SIZE];
+  static char buffer[time_constants::ASCTIME_BUFFER_SIZE];
   return time_utils::asctime(time_utils::localtime(t_ptr), buffer,
-                             TimeConstants::ASCTIME_MAX_BYTES);
+                             time_constants::ASCTIME_MAX_BYTES);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/ctime_r.cpp b/libc/src/time/ctime_r.cpp
index 63d93c4085f38c..c7f7414d8f93cd 100644
--- a/libc/src/time/ctime_r.cpp
+++ b/libc/src/time/ctime_r.cpp
@@ -14,8 +14,6 @@
 
 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 == nullptr || buffer == nullptr ||
       *t_ptr > cpp::numeric_limits<int32_t>::max()) {
@@ -23,7 +21,7 @@ LLVM_LIBC_FUNCTION(char *, ctime_r, (const time_t *t_ptr, char *buffer)) {
   }
 
   return time_utils::asctime(time_utils::localtime(t_ptr), buffer,
-                             TimeConstants::ASCTIME_MAX_BYTES);
+                             time_constants::ASCTIME_MAX_BYTES);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/difftime.h b/libc/src/time/difftime.h
index d5cd593cc53350..12de5678864c70 100644
--- a/libc/src/time/difftime.h
+++ b/libc/src/time/difftime.h
@@ -9,8 +9,8 @@
 #ifndef LLVM_LIBC_SRC_TIME_DIFFTIME_H
 #define LLVM_LIBC_SRC_TIME_DIFFTIME_H
 
+#include "hdr/types/time_t.h"
 #include "src/__support/macros/config.h"
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/gmtime.h b/libc/src/time/gmtime.h
index 3de3cebbfde2ca..ac7f1be7bbce89 100644
--- a/libc/src/time/gmtime.h
+++ b/libc/src/time/gmtime.h
@@ -9,8 +9,9 @@
 #ifndef LLVM_LIBC_SRC_TIME_GMTIME_H
 #define LLVM_LIBC_SRC_TIME_GMTIME_H
 
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
 #include "src/__support/macros/config.h"
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/gmtime_r.h b/libc/src/time/gmtime_r.h
index b4f387ef443bca..4c88b22faf4cff 100644
--- a/libc/src/time/gmtime_r.h
+++ b/libc/src/time/gmtime_r.h
@@ -9,8 +9,9 @@
 #ifndef LLVM_LIBC_SRC_TIME_GMTIME_R_H
 #define LLVM_LIBC_SRC_TIME_GMTIME_R_H
 
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
 #include "src/__support/macros/config.h"
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/mktime.cpp b/libc/src/time/mktime.cpp
index b5d1da5fa8fba1..f4756d2db216c2 100644
--- a/libc/src/time/mktime.cpp
+++ b/libc/src/time/mktime.cpp
@@ -13,11 +13,6 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
-using LIBC_NAMESPACE::time_utils::TimeConstants;
-
-static constexpr int NON_LEAP_YEAR_DAYS_IN_MONTH[] = {31, 28, 31, 30, 31, 30,
-                                                      31, 31, 30, 31, 30, 31};
-
 // Returns number of years from (1, year).
 static constexpr int64_t get_num_of_leap_years_before(int64_t year) {
   return (year / 4) - (year / 100) + (year / 400);
@@ -31,12 +26,12 @@ static constexpr bool is_leap_year(const int64_t year) {
 LLVM_LIBC_FUNCTION(time_t, mktime, (struct tm * tm_out)) {
   // Unlike most C Library functions, mktime doesn't just die on bad input.
   // TODO(rtenneti); Handle leap seconds.
-  int64_t tm_year_from_base = tm_out->tm_year + TimeConstants::TIME_YEAR_BASE;
+  int64_t tm_year_from_base = tm_out->tm_year + time_constants::TIME_YEAR_BASE;
 
   // 32-bit end-of-the-world is 03:14:07 UTC on 19 January 2038.
   if (sizeof(time_t) == 4 &&
-      tm_year_from_base >= TimeConstants::END_OF32_BIT_EPOCH_YEAR) {
-    if (tm_year_from_base > TimeConstants::END_OF32_BIT_EPOCH_YEAR)
+      tm_year_from_base >= time_constants::END_OF32_BIT_EPOCH_YEAR) {
+    if (tm_year_from_base > time_constants::END_OF32_BIT_EPOCH_YEAR)
       return time_utils::out_of_range();
     if (tm_out->tm_mon > 0)
       return time_utils::out_of_range();
@@ -64,7 +59,7 @@ LLVM_LIBC_FUNCTION(time_t, mktime, (struct tm * tm_out)) {
 
   // Calculate number of months and years from tm_mon.
   int64_t month = tm_out->tm_mon;
-  if (month < 0 || month >= TimeConstants::MONTHS_PER_YEAR - 1) {
+  if (month < 0 || month >= time_constants::MONTHS_PER_YEAR - 1) {
     int64_t years = month / 12;
     month %= 12;
     if (month < 0) {
@@ -78,23 +73,23 @@ LLVM_LIBC_FUNCTION(time_t, mktime, (struct tm * tm_out)) {
   // Calculate total number of days based on the month and the day (tm_mday).
   int64_t total_days = tm_out->tm_mday - 1;
   for (int64_t i = 0; i < month; ++i)
-    total_days += NON_LEAP_YEAR_DAYS_IN_MONTH[i];
+    total_days += time_constants::NON_LEAP_YEAR_DAYS_IN_MONTH[i];
   // Add one day if it is a leap year and the month is after February.
   if (tm_year_is_leap && month > 1)
     total_days++;
 
   // Calculate total numbers of days based on the year.
-  total_days += (tm_year_from_base - TimeConstants::EPOCH_YEAR) *
-                TimeConstants::DAYS_PER_NON_LEAP_YEAR;
-  if (tm_year_from_base >= TimeConstants::EPOCH_YEAR) {
+  total_days += (tm_year_from_base - time_constants::EPOCH_YEAR) *
+                time_constants::DAYS_PER_NON_LEAP_YEAR;
+  if (tm_year_from_base >= time_constants::EPOCH_YEAR) {
     total_days += get_num_of_leap_years_before(tm_year_from_base - 1) -
-                  get_num_of_leap_years_before(TimeConstants::EPOCH_YEAR);
+                  get_num_of_leap_years_before(time_constants::EPOCH_YEAR);
   } else if (tm_year_from_base >= 1) {
-    total_days -= get_num_of_leap_years_before(TimeConstants::EPOCH_YEAR) -
+    total_days -= get_num_of_leap_years_before(time_constants::EPOCH_YEAR) -
                   get_num_of_leap_years_before(tm_year_from_base - 1);
   } else {
     // Calculate number of leap years until 0th year.
-    total_days -= get_num_of_leap_years_before(TimeConstants::EPOCH_YEAR) -
+    total_days -= get_num_of_leap_years_before(time_constants::EPOCH_YEAR) -
                   get_num_of_leap_years_before(0);
     if (tm_year_from_base <= 0) {
       total_days -= 1; // Subtract 1 for 0th year.
@@ -109,9 +104,9 @@ LLVM_LIBC_FUNCTION(time_t, mktime, (struct tm * tm_out)) {
   // TODO: https://github.com/llvm/llvm-project/issues/121962
   // Need to handle timezone and update of tm_isdst.
   int64_t seconds = tm_out->tm_sec +
-                    tm_out->tm_min * TimeConstants::SECONDS_PER_MIN +
-                    tm_out->tm_hour * TimeConstants::SECONDS_PER_HOUR +
-                    total_days * TimeConstants::SECONDS_PER_DAY;
+                    tm_out->tm_min * time_constants::SECONDS_PER_MIN +
+                    tm_out->tm_hour * time_constants::SECONDS_PER_HOUR +
+                    total_days * time_constants::SECONDS_PER_DAY;
 
   // Update the tm structure's year, month, day, etc. from seconds.
   if (time_utils::update_from_seconds(seconds, tm_out) < 0)
diff --git a/libc/src/time/mktime.h b/libc/src/time/mktime.h
index 2b4c67996555e8..985c6293f9d512 100644
--- a/libc/src/time/mktime.h
+++ b/libc/src/time/mktime.h
@@ -9,8 +9,9 @@
 #ifndef LLVM_LIBC_SRC_TIME_MKTIME_H
 #define LLVM_LIBC_SRC_TIME_MKTIME_H
 
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
 #include "src/__support/macros/config.h"
-#include <time.h>
 
 namespace LIBC_NAMESPACE_DECL {
 
diff --git a/libc/src/time/time_constants.h b/libc/src/time/time_constants.h
new file mode 100644
index 00000000000000..17f4408ef54bd3
--- /dev/null
+++ b/libc/src/time/time_constants.h
@@ -0,0 +1,104 @@
+//===-- Collection of constants for time functions --------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_TIME_TIME_CONSTANTS_H
+#define LLVM_LIBC_SRC_TIME_TIME_CONSTANTS_H
+
+#include "hdr/types/time_t.h"
+#include "src/__support/CPP/array.h"
+#include "src/__support/CPP/string_view.h"
+#include <stdint.h>
+
+namespace LIBC_NAMESPACE_DECL {
+namespace time_constants {
+
+enum Month : int {
+  JANUARY,
+  FEBRUARY,
+  MARCH,
+  APRIL,
+  MAY,
+  JUNE,
+  JULY,
+  AUGUST,
+  SEPTEMBER,
+  OCTOBER,
+  NOVEMBER,
+  DECEMBER
+};
+
+constexpr int SECONDS_PER_MIN = 60;
+constexpr int MINUTES_PER_HOUR = 60;
+constexpr int HOURS_PER_DAY = 24;
+constexpr int DAYS_PER_WEEK = 7;
+constexpr int MONTHS_PER_YEAR = 12;
+constexpr int DAYS_PER_NON_LEAP_YEAR = 365;
+constexpr int DAYS_PER_LEAP_YEAR = 366;
+
+constexpr int SECONDS_PER_HOUR = SECONDS_PER_MIN * MINUTES_PER_HOUR;
+constexpr int SECONDS_PER_DAY = SECONDS_PER_HOUR * HOURS_PER_DAY;
+constexpr int NUMBER_OF_SECONDS_IN_LEAP_YEAR =
+    DAYS_PER_LEAP_YEAR * SECONDS_PER_DAY;
+
+constexpr int TIME_YEAR_BASE = 1900;
+constexpr int EPOCH_YEAR = 1970;
+constexpr int EPOCH_WEEK_DAY = 4;
+
+// For asctime the behavior is undefined if struct tm's tm_wday or tm_mon are
+// not within the normal ranges as defined in <time.h>, or if struct tm's
+// tm_year exceeds {INT_MAX}-1990, or if the below asctime_internal algorithm
+// would attempt to generate more than 26 bytes of output (including the
+// terminating null).
+constexpr int ASCTIME_BUFFER_SIZE = 256;
+constexpr int ASCTIME_MAX_BYTES = 26;
+
+/* 2000-03-01 (mod 400 year, immediately after feb29 */
+constexpr int64_t SECONDS_UNTIL2000_MARCH_FIRST =
+    (946684800LL + SECONDS_PER_DAY * (31 + 29));
+constexpr int WEEK_DAY_OF2000_MARCH_FIRST = 3;
+
+constexpr int DAYS_PER400_YEARS =
+    (DAYS_PER_NON_LEAP_YEAR * 400) + (400 / 4) - 3;
+constexpr int DAYS_PER100_YEARS =
+    (DAYS_PER_NON_LEAP_YEAR * 100) + (100 / 4) - 1;
+constexpr int DAYS_PER4_YEARS = (DAYS_PER_NON_LEAP_YEAR * 4) + 1;
+
+// The latest time that can be represented in this form is 03:14:07 UTC on
+// Tuesday, 19 January 2038 (corresponding to 2,147,483,647 seconds since the
+// start of the epoch). This means that systems using a 32-bit time_t type are
+// susceptible to the Year 2038 problem.
+constexpr int END_OF32_BIT_EPOCH_YEAR = 2038;
+
+constexpr time_t OUT_OF_RANGE_RETURN_VALUE = -1;
+
+constexpr cpp::array<cpp::string_view, DAYS_PER_WEEK> WEEK_DAY_NAMES = {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
+
+constexpr cpp::array<cpp::string_view, DAYS_PER_WEEK> WEEK_DAY_FULL_NAMES = {
+    "Sunday",   "Monday", "Tuesday", "Wednesday",
+    "Thursday", "Friday", "Saturday"};
+
+constexpr cpp::array<cpp::string_view, MONTHS_PER_YEAR> MONTH_NAMES = {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+
+constexpr cpp::array<cpp::string_view, MONTHS_PER_YEAR> MONTH_FULL_NAMES = {
+    "January", "February", "March",     "April",   "May",      "June",
+    "July",    "August",   "September", "October", "November", "December"};
+
+constexpr int NON_LEAP_YEAR_DAYS_IN_MONTH[] = {31, 28, 31, 30, 31, 30,
+                                               31, 31, 30, 31, 30, 31};
+
+// LIBC_INLINE constexpr cpp::string_view get_day_name(int day) {
+//   if(day < )
+// }
+
+} // namespace time_constants
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_TIME_CONSTANTS_H
diff --git a/libc/src/time/time_utils.cpp b/libc/src/time/time_utils.cpp
index 509cad8146df87..71a1fbb2cfe9cc 100644
--- a/libc/src/time/time_utils.cpp
+++ b/libc/src/time/time_utils.cpp
@@ -14,8 +14,6 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace time_utils {
 
-using LIBC_NAMESPACE::time_utils::TimeConstants;
-
 static int64_t computeRemainingYears(int64_t daysPerYears,
                                      int64_t quotientYears,
                                      int64_t *remainingDays) {
@@ -52,36 +50,36 @@ int64_t update_from_seconds(int64_t total_seconds, struct tm *tm) {
       (sizeof(time_t) == 4)
           ? INT_MIN
           : INT_MIN * static_cast<int64_t>(
-                          TimeConstants::NUMBER_OF_SECONDS_IN_LEAP_YEAR);
+                          time_constants::NUMBER_OF_SECONDS_IN_LEAP_YEAR);
   constexpr time_t time_max =
       (sizeof(time_t) == 4)
           ? INT_MAX
           : INT_MAX * static_cast<int64_t>(
-                          TimeConstants::NUMBER_OF_SECONDS_IN_LEAP_YEAR);
+                          time_constants::NUMBER_OF_SECONDS_IN_LEAP_YEAR);
 
   time_t ts = static_cast<time_t>(total_seconds);
   if (ts < time_min || ts > time_max)
     return time_utils::out_of_range();
 
   int64_t seconds =
-      total_seconds - TimeConstants::SECONDS_UNTIL2000_MARCH_FIRST;
-  int64_t days = seconds / TimeConstants::SECONDS_PER_DAY;
-  int64_t remainingSeconds = seconds % TimeConstants::SECONDS_PER_DAY;
+      total_seconds - time_constants::SECONDS_UNTIL2000_MARCH_FIRST;
+  int64_t days = seconds / time_constants::SECONDS_PER_DAY;
+  int64_t remainingSeconds = seconds % time_constants::SECONDS_PER_DAY;
   if (remainingSeconds < 0) {
-    remainingSeconds += TimeConstants::SECONDS_PER_DAY;
+    remainingSeconds += time_constants::SECONDS_PER_DAY;
     days--;
   }
 
-  int64_t wday = (TimeConstants::WEEK_DAY_OF2000_MARCH_FIRST + days) %
-                 TimeConstants::DAYS_PER_WEEK;
+  int64_t wday = (time_constants::WEEK_DAY_OF2000_MARCH_FIRST + days) %
+                 time_constants::DAYS_PER_WEEK;
   if (wday < 0...
[truncated]

SchrodingerZhu

LGTM.

libc/test/src/time/TmHelper.h

libc/src/pthread/pthread_condattr_init.cpp

libc/src/time/ctime.cpp

llvmbot added the libc label Jan 8, 2025

michaelrj-google requested review from SchrodingerZhu, lntue and nickdesaulniers January 8, 2025 00:22

remove commented out function stub

9d5bd3c

SchrodingerZhu approved these changes Jan 8, 2025

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jhuber6 approved these changes Jan 8, 2025

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address comment

4adc253

nickdesaulniers approved these changes Jan 8, 2025

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michaelrj-google added 2 commits January 8, 2025 10:44

re-add macro comments, clean up includes.

788f962

update cmake for new deps

dd70c4c

michaelrj-google merged commit f9c2377 into llvm:main Jan 8, 2025
9 of 10 checks passed

michaelrj-google deleted the libcTimeCleanup branch January 8, 2025 20:29

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[libc][NFC] Cleanup time.h #122027

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