[libc][NFC] Cleanup time.h (llvm#122027)

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.

Author: michaelrj-google

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

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

libc/src/pthread/pthread_condattr_init.cpp

@@ -11,8 +11,8 @@
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
 
-#include <pthread.h> // pthread_condattr_t, PTHREAD_PROCESS_PRIVATE
-#include <time.h>    // CLOCK_REALTIME
+#include "hdr/time_macros.h" // CLOCK_REALTIME
+#include <pthread.h>         // pthread_condattr_t, PTHREAD_PROCESS_PRIVATE
 
 namespace LIBC_NAMESPACE_DECL {
 

libc/src/pthread/pthread_condattr_setclock.cpp

@@ -12,9 +12,9 @@
 #include "src/__support/macros/config.h"
 #include "src/errno/libc_errno.h"
 
-#include <pthread.h>   // pthread_condattr_t
-#include <sys/types.h> // clockid_t
-#include <time.h>      // CLOCK_MONOTONIC, CLOCK_REALTIME
+#include "hdr/time_macros.h" // CLOCK_MONOTONIC, CLOCK_REALTIME
+#include <pthread.h>         // pthread_condattr_t
+#include <sys/types.h>       // clockid_t
 
 namespace LIBC_NAMESPACE_DECL {
 

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(
@@ -22,7 +37,9 @@ add_entrypoint_object(
     asctime.h
   DEPENDS
     .time_utils
+    .time_constants
     libc.include.time
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -33,7 +50,9 @@ add_entrypoint_object(
     asctime_r.h
   DEPENDS
     .time_utils
+    .time_constants
     libc.include.time
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -44,6 +63,7 @@ add_entrypoint_object(
     ctime.h
   DEPENDS
     .time_utils
+    .time_constants
     libc.hdr.types.time_t
     libc.include.time
 )
@@ -56,6 +76,7 @@ add_entrypoint_object(
     ctime_r.h
   DEPENDS
     .time_utils
+    .time_constants
     libc.hdr.types.time_t
     libc.include.time
 )
@@ -68,6 +89,7 @@ add_entrypoint_object(
     difftime.h
   DEPENDS
     libc.include.time
+    libc.hdr.types.time_t
 )
 
 add_entrypoint_object(
@@ -79,6 +101,8 @@ add_entrypoint_object(
   DEPENDS
     .time_utils
     libc.include.time
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -90,6 +114,8 @@ add_entrypoint_object(
   DEPENDS
     .time_utils
     libc.include.time
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -100,8 +126,11 @@ add_entrypoint_object(
     mktime.h
   DEPENDS
     .time_utils
+    .time_constants
     libc.include.time
     libc.src.errno.errno
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
 )
 
 add_entrypoint_object(
@@ -115,6 +144,7 @@ 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(

libc/src/time/asctime.cpp

@@ -9,15 +9,15 @@
 #include "src/time/asctime.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, (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

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 {
 

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

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 {
 

libc/src/time/ctime.cpp

@@ -6,23 +6,22 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "ctime.h"
+#include "src/time/ctime.h"
 #include "src/__support/CPP/limits.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
-#include "time_utils.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 *, 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