Fix some timezone issues

docs/datetime.md

@@ -16,7 +16,7 @@ preferred representation of the DateTime in the current time zone:
 
 ```tomo
 >> DateTime.now()
-= Sun Sep 29 18:20:12 2024
+= Sun Sep 29 18:20:12 2024 EDT
 ```
 
 For various methods, it is assumed by default that users wish to perform
@@ -71,7 +71,7 @@ A new `DateTime` offset by the given amount.
 **Example:**  
 ```markdown
 >> DateTime(2024, 9, 29, hour=19):after(days=1, minutes=30)
-= Mon Sep 30 19:30:00 2024
+= Mon Sep 30 19:30:00 2024 EDT
 ```
 
 ---
@@ -111,7 +111,7 @@ options, return a text representation of the given date in the given format. If
 
 **Usage:**  
 ```markdown
-datetime:format(format: Text = "%c", local_time : Bool = yes) -> Text
+datetime:format(format: Text = "%c %Z", local_time : Bool = yes) -> Text
 ```
 
 **Parameters:**
@@ -278,11 +278,11 @@ integer, an error will be raised.
 **Example:**  
 ```markdown
 >> DateTime.new(2024, 9, 29)
-= Mon Sep 30 00:00:00 2024
+= Mon Sep 30 00:00:00 2024 EDT
 
 # March 1642, 2020:
 >> DateTime(2020, 4, 1643)
-= Sat Sep 28 00:00:00 2024
+= Sat Sep 28 00:00:00 2024 EDT
 ```
 
 ---
@@ -308,7 +308,7 @@ Returns a `DateTime` object representing the current date and time.
 **Example:**  
 ```markdown
 >> DateTime.now()
-= Sun Sep 29 20:22:48 2024
+= Sun Sep 29 20:22:48 2024 EDT
 ```
 
 ---
@@ -321,14 +321,14 @@ or a null value if the value could not be successfully parsed.
 
 **Usage:**  
 ```markdown
-DateTime.parse(text: Text, format: Text = "%c") -> DateTime?
+DateTime.parse(text: Text, format: Text = "%Y-%m-%dT%H:%M:%S. %f%z") -> DateTime?
 ```
 
 **Parameters:**
 
 - `text`: The text to parse.
 - `format`: The date format of the text being parsed (see:
-  [strptime](https://linux.die.net/man/3/strptime) for more info on this format) (default: `"%c"`).
+  [strptime](https://linux.die.net/man/3/strptime) for more info on this format) (default: `"%c %Z"`).
 
 **Returns:**
 If the text was successfully parsed according to the given format, return a
@@ -337,7 +337,7 @@ If the text was successfully parsed according to the given format, return a
 **Example:**  
 ```markdown
 >> DateTime.parse("2024-09-29", "%Y-%m-%d")!
-= Sun Sep 29 00:00:00 2024
+= Sun Sep 29 00:00:00 2024 EDT
 
 >> DateTime.parse("???", "%Y-%m-%d")
 = !DateTime

environment.c

@@ -267,13 +267,13 @@ env_t *new_compilation_unit(CORD libname)
 
             {"after", "DateTime$after", "func(dt:DateTime,seconds=0.0,minutes=0.0,hours=0.0,days=0,weeks=0,months=0,years=0,local_time=yes)->DateTime"},
             {"date", "DateTime$date", "func(dt:DateTime,local_time=yes)->Text"},
-            {"format", "DateTime$format", "func(dt:DateTime,format=\"%c\",local_time=yes)->Text"},
+            {"format", "DateTime$format", "func(dt:DateTime,format=\"%Y-%m-%dT%H:%M:%S%z\",local_time=yes)->Text"},
             {"from_unix_timestamp", "DateTime$from_unix_timestamp", "func(timestamp:Int64)->DateTime"},
             {"get", "DateTime$get", "func(dt:DateTime,year=!&Int,month=!&Int,day=!&Int,hour=!&Int,minute=!&Int,second=!&Int,nanosecond=!&Int,weekday=!&Int, local_time=yes)"},
             {"hours_till", "DateTime$hours_till", "func(now:DateTime,then:DateTime)->Num"},
             {"minutes_till", "DateTime$minutes_till", "func(now:DateTime,then:DateTime)->Num"},
             {"new", "DateTime$new", "func(year:Int,month:Int,day:Int,hour=0,minute=0,second=0.0)->DateTime"},
-            {"parse", "DateTime$parse", "func(text:Text, format=\"%c\")->DateTime?"},
+            {"parse", "DateTime$parse", "func(text:Text, format=\"%Y-%m-%dT%H:%M:%S%z\")->DateTime?"},
             {"relative", "DateTime$relative", "func(dt:DateTime,relative_to=DateTime.now(),local_time=yes)->Text"},
             {"seconds_till", "DateTime$seconds_till", "func(now:DateTime,then:DateTime)->Num"},
             {"time", "DateTime$time", "func(dt:DateTime,seconds=no,am_pm=yes,local_time=yes)->Text"},

stdlib/datetime.c

@@ -21,7 +21,7 @@ public Text_t DateTime$as_text(const DateTime_t *dt, bool colorize, const TypeIn
     struct tm info;
     struct tm *final_info = localtime_r(&dt->tv_sec, &info);
     static char buf[256];
-    size_t len = strftime(buf, sizeof(buf), "%c", final_info);
+    size_t len = strftime(buf, sizeof(buf), "%c %Z", final_info);
     Text_t text = Text$format("%.*s", (int)len, buf);
     if (colorize)
         text = Text$concat(Text("\x1b[36m"), text, Text("\x1b[m"));
@@ -141,12 +141,18 @@ public Text_t DateTime$time(DateTime_t dt, bool seconds, bool am_pm, bool local_
 public OptionalDateTime_t DateTime$parse(Text_t text, Text_t format)
 {
     struct tm info = {.tm_isdst=-1};
-    char *invalid = strptime(Text$as_c_string(text), Text$as_c_string(format), &info);
+    const char *str = Text$as_c_string(text);
+    const char *fmt = Text$as_c_string(format);
+    if (strstr(fmt, "%Z"))
+        fail("The %%Z specifier is not supported for time parsing!");
+
+    char *invalid = strptime(str, fmt, &info);
     if (!invalid || invalid[0] != '\0')
         return NULL_DATETIME;
 
+    long offset = info.tm_gmtoff; // Need to cache this because mktime() mutates it to local timezone >:(
     time_t t = mktime(&info);
-    return (DateTime_t){.tv_sec=t};
+    return (DateTime_t){.tv_sec=t + offset - info.tm_gmtoff};
 }
 
 static inline Text_t num_format(long n, const char *unit)
@@ -195,7 +201,7 @@ public Text_t DateTime$relative(DateTime_t dt, DateTime_t relative_to, bool loca
 
 CONSTFUNC public Int64_t DateTime$unix_timestamp(DateTime_t dt)
 {
-    return (Int64_t)(dt.tv_sec);
+    return (Int64_t)dt.tv_sec;
 }
 
 CONSTFUNC public DateTime_t DateTime$from_unix_timestamp(Int64_t timestamp)