vim-patch:8.1.2326: cannot parse a date/time string

Problem:    Cannot parse a date/time string.
Solution:   Add strptime(). (Stephen Wall, closes #)
https://github.com/vim/vim/commit/10455d43fef041309ce0613fa792c635dd71e3a8

N/A patches for version.c:

vim-patch:8.1.2344: Cygwin: warning for using strptime()

Problem:    Cygwin: warning for using strptime().
Solution:   Move defining _XOPEN_SOURCE and __USE_XOPEN to vim.h. (Ken Takata,
            closes vim/vim#5265)  Use 700 for _XOPEN_SOURCE for mkdtemp().
https://github.com/vim/vim/commit/6a228c6463935a73c8f21142cb7368545cfee317

8 files changed, 108 insertions, 8 deletions

diff --git a/config/CMakeLists.txt b/config/CMakeLists.txt
index 8a70d864c4..6b88c92cf0 100644
--- a/config/CMakeLists.txt
+++ b/config/CMakeLists.txt
@@ -52,6 +52,7 @@ check_function_exists(setsid HAVE_SETSID)
 check_function_exists(sigaction HAVE_SIGACTION)
 check_function_exists(strcasecmp HAVE_STRCASECMP)
 check_function_exists(strncasecmp HAVE_STRNCASECMP)
+check_function_exists(strptime HAVE_STRPTIME)
 
 # Symbols
 check_symbol_exists(FD_CLOEXEC "fcntl.h" HAVE_FD_CLOEXEC)
diff --git a/config/config.h.in b/config/config.h.in
index 275bff79a0..502f84bbcf 100644
--- a/config/config.h.in
+++ b/config/config.h.in
@@ -33,6 +33,7 @@
 #cmakedefine HAVE_STRCASECMP
 #cmakedefine HAVE_STRINGS_H
 #cmakedefine HAVE_STRNCASECMP
+#cmakedefine HAVE_STRPTIME
 #cmakedefine HAVE_SYS_SDT_H
 #cmakedefine HAVE_SYS_UTSNAME_H
 #cmakedefine HAVE_SYS_WAIT_H
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 1832e2443f..112958f78b 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -444,7 +444,7 @@ as a key.
 To avoid having to put quotes around every key the #{} form can be used.  This
 does require the key to consist only of ASCII letters, digits, '-' and '_'.
 Example: >
-	let mydict = #{zero: 0, one_key: 1, two-key: 2, 333: 3}
+	:let mydict = #{zero: 0, one_key: 1, two-key: 2, 333: 3}
 Note that 333 here is the string "333".  Empty keys are not possible with #{}.
 
 A value can be any expression.  Using a Dictionary for a value creates a
@@ -2430,7 +2430,7 @@ strcharpart({str}, {start} [, {len}])
 				String	{len} characters of {str} at
 					character {start}
 strdisplaywidth({expr} [, {col}]) Number display length of the String {expr}
-strftime({format} [, {time}])	String	time in specified format
+strftime({format} [, {time}])	String	format time with a specified format
 strgetchar({str}, {index})	Number	get char {index} from {str}
 stridx({haystack}, {needle} [, {start}])
 				Number	index of {needle} in {haystack}
@@ -2439,6 +2439,8 @@ strlen({expr})			Number	length of the String {expr}
 strpart({str}, {start} [, {len} [, {chars}]])
 				String	{len} bytes/chars of {str} at
 					byte {start}
+strptime({format}, {timestring})
+				Number	Convert {timestring} to unix timestamp
 strridx({haystack}, {needle} [, {start}])
 				Number	last index of {needle} in {haystack}
 strtrans({expr})		String	translate string to make it printable
@@ -4983,7 +4985,7 @@ getwininfo([{winid}])					*getwininfo()*
 
 getwinpos([{timeout}])					*getwinpos()*
 		The result is a list with two numbers, the result of
-		getwinposx() and getwinposy() combined:
+		|getwinposx()| and |getwinposy()| combined:
 			[x-pos, y-pos]
 		{timeout} can be used to specify how long to wait in msec for
 		a response from the terminal.  When omitted 100 msec is used.
@@ -5853,7 +5855,7 @@ list2str({list} [, {utf8}])				*list2str()*
 <
 localtime()						*localtime()*
 		Return the current time, measured as seconds since 1st Jan
-		1970.  See also |strftime()| and |getftime()|.
+		1970.  See also |strftime()|, |strptime()| and |getftime()|.
 
 
 log({expr})						*log()*
@@ -8488,7 +8490,7 @@ strftime({format} [, {time}])				*strftime()*
 		{format} depends on your system, thus this is not portable!
 		See the manual page of the C function strftime() for the
 		format.  The maximum length of the result is 80 characters.
-		See also |localtime()| and |getftime()|.
+		See also |localtime()|, |getftime()| and |strptime()|.
 		The language can be changed with the |:language| command.
 		Examples: >
 		  :echo strftime("%c")		   Sun Apr 27 11:49:23 1997
@@ -8578,6 +8580,31 @@ strpart({src}, {start} [, {len} [, {chars}]])			*strpart()*
 		example, to get the character under the cursor: >
 			strpart(getline("."), col(".") - 1, 1, v:true)
 <
+strptime({format}, {timestring})				*strptime()*
+		The result is a Number, which is a unix timestamp representing
+		the date and time in {timestring}, which is expected to match
+		the format specified in {format}.
+
+		The accepted {format} depends on your system, thus this is not
+		portable!  See the manual page of the C function strptime()
+		for the format.  Especially avoid "%c".  The value of $TZ also
+		matters.
+
+		If the {timestring} cannot be parsed with {format} zero is
+		returned.  If you do not know the format of {timestring} you
+		can try different {format} values until you get a non-zero
+		result.
+
+		See also |strftime()|.
+		Examples: >
+		  :echo strptime("%Y %b %d %X", "1997 Apr 27 11:49:23")
+<		  862156163 >
+		  :echo strftime("%c", strptime("%y%m%d %T", "970427 11:53:55"))
+<		  Sun Apr 27 11:53:55 1997 >
+		  :echo strftime("%c", strptime("%Y%m%d%H%M%S", "19970427115355") + 3600)
+<		  Sun Apr 27 12:53:55 1997
+
+
 strridx({haystack}, {needle} [, {start}])			*strridx()*
 		The result is a Number, which gives the byte index in
 		{haystack} of the last occurrence of the String {needle}.
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index 63c899da0c..97aacc1403 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -788,6 +788,7 @@ Date and Time:				*date-functions* *time-functions*
 	getftime()		get last modification time of a file
 	localtime()		get current time in seconds
 	strftime()		convert time to a string
+	strptime()		convert a date/time string to time
 	reltime()		get the current or elapsed time accurately
 	reltimestr()		convert reltime() result to a string
 	reltimefloat()		convert reltime() result to a Float
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index e94d7831b0..d1a3ae3ff8 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -341,6 +341,7 @@ return {
     string={args=1},
     strlen={args=1},
     strpart={args={2, 4}},
+    strptime={args=2},
     strridx={args={2, 3}},
     strtrans={args=1},
     strwidth={args=1},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 01d23654de..145a7a4733 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -10189,6 +10189,36 @@ static void f_strpart(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   rettv->vval.v_string = (char_u *)xmemdupz(p + n, (size_t)len);
 }
 
+// "strptime({format}, {timestring})" function
+static void f_strptime(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  char fmt_buf[NUMBUFLEN];
+  char str_buf[NUMBUFLEN];
+
+  struct tm tmval = { 0 };
+  char *fmt = (char *)tv_get_string_buf(&argvars[0], fmt_buf);
+  char *str = (char *)tv_get_string_buf(&argvars[1], str_buf);
+
+  vimconv_T conv = {
+    .vc_type = CONV_NONE,
+  };
+  char_u *enc = enc_locale();
+  convert_setup(&conv, p_enc, enc);
+  if (conv.vc_type != CONV_NONE) {
+    fmt = (char *)string_convert(&conv, (char_u *)fmt, NULL);
+  }
+  if (fmt == NULL
+      || os_strptime(str, fmt, &tmval) == NULL
+      || (rettv->vval.v_number = mktime(&tmval)) == -1) {
+    rettv->vval.v_number = 0;
+  }
+  if (conv.vc_type != CONV_NONE) {
+    xfree(fmt);
+  }
+  convert_setup(&conv, NULL, NULL);
+  xfree(enc);
+}
+
 /*
  * "strridx()" function
  */
diff --git a/src/nvim/os/time.c b/src/nvim/os/time.c
index 5cf628935f..e7e0dc4013 100644
--- a/src/nvim/os/time.c
+++ b/src/nvim/os/time.c
@@ -196,6 +196,22 @@ char *os_ctime(char *result, size_t result_len)
   return os_ctime_r(&rawtime, result, result_len);
 }
 
+/// Portable version of POSIX strptime()
+///
+/// @param str[in]  string to convert
+/// @param format[in]  format to parse "str"
+/// @param tm[out]  time representation of "str"
+/// @return Pointer to first unprocessed character or NULL
+char *os_strptime(const char *str, const char *format, struct tm *tm)
+  FUNC_ATTR_NONNULL_ALL
+{
+#ifdef HAVE_STRPTIME
+  return strptime(str, format, tm);
+#else
+  return NULL;
+#endif
+}
+
 /// Obtains the current Unix timestamp.
 ///
 /// @return Seconds since epoch.
diff --git a/src/nvim/testdir/test_functions.vim b/src/nvim/testdir/test_functions.vim
index 5dae8d681a..5efd27d016 100644
--- a/src/nvim/testdir/test_functions.vim
+++ b/src/nvim/testdir/test_functions.vim
@@ -1,5 +1,7 @@
 " Tests for various functions.
+
 source shared.vim
+source check.vim
 
 " Must be done first, since the alternate buffer must be unset.
 func Test_00_bufexists()
@@ -171,9 +173,8 @@ func Test_str2nr()
 endfunc
 
 func Test_strftime()
-  if !exists('*strftime')
-    return
-  endif
+  CheckFunction strftime
+
   " Format of strftime() depends on system. We assume
   " that basic formats tested here are available and
   " identical on all systems which support strftime().
@@ -214,6 +215,28 @@ func Test_strftime()
   endif
 endfunc
 
+func Test_strptime()
+  CheckFunction strptime
+
+  if exists('$TZ')
+    let tz = $TZ
+  endif
+  let $TZ = 'UTC'
+
+  call assert_equal(1484653763, strptime('%Y-%m-%d %X', '2017-01-17 11:49:23'))
+
+  call assert_fails('call strptime()', 'E119:')
+  call assert_fails('call strptime("xxx")', 'E119:')
+  call assert_equal(0, strptime("%Y", ''))
+  call assert_equal(0, strptime("%Y", "xxx"))
+
+  if exists('tz')
+    let $TZ = tz
+  else
+    unlet $TZ
+  endif
+endfunc
+
 func Test_resolve_unix()
   if !has('unix')
     return