From f4c42b4f143844256e41bd2ebb4c30fd41c4d2ff Mon Sep 17 00:00:00 2001
From: Aleksandr Bashurov <45628798+abashurov@users.noreply.github.com>
Date: Fri, 21 Aug 2020 22:56:10 +0700
Subject: [PATCH] Skip IANA TZ names when parsing %Z specifier (#473)

---
 CHANGELOG.md           |  5 +++++
 src/format/parse.rs    | 12 ++++++++++--
 src/format/scan.rs     |  6 ++++++
 src/format/strftime.rs | 11 ++++++++++-
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 51829535e2..7068bc963e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,11 @@ Versions with only mechanical changes will be omitted from the following list.
 
 ## 0.4.16 (unreleased)
 
+### Features
+
+* Add %Z specifier to the `FromStr`, similar to the glibc strptime
+  (does not set the offset from the timezone name)
+
 ## 0.4.15
 
 ### Fixes
diff --git a/src/format/parse.rs b/src/format/parse.rs
index e784eac0f9..2fce8277b1 100644
--- a/src/format/parse.rs
+++ b/src/format/parse.rs
@@ -407,7 +407,9 @@ where
                         parsed.set_nanosecond(nano).map_err(|e| (s, e))?;
                     }
 
-                    &TimezoneName => return Err((s, BAD_FORMAT)),
+                    &TimezoneName => {
+                        try_consume!(scan::timezone_name_skip(s));
+                    }
 
                     &TimezoneOffsetColon | &TimezoneOffset => {
                         let offset = try_consume!(scan::timezone_offset(
@@ -752,7 +754,7 @@ fn test_parse() {
     check!("z",         [internal_fix!(TimezoneOffsetPermissive)]; offset: 0);
     check!("+12:00",    [internal_fix!(TimezoneOffsetPermissive)]; offset: 12 * 60 * 60);
     check!("+12",       [internal_fix!(TimezoneOffsetPermissive)]; offset: 12 * 60 * 60);
-    check!("???",       [fix!(TimezoneName)]; BAD_FORMAT); // not allowed
+    check!("CEST 5",    [fix!(TimezoneName), lit!(" "), num!(Day)]; day: 5);
 
     // some practical examples
     check!("2015-02-04T14:37:05+09:00",
@@ -771,6 +773,12 @@ fn test_parse() {
             num!(Minute), lit!(":"), num!(Second), sp!(" "), lit!("GMT")];
            year: 2013, month: 6, day: 10, weekday: Weekday::Mon,
            hour_div_12: 0, hour_mod_12: 9, minute: 32, second: 37);
+    check!("Sun Aug 02 13:39:15 CEST 2020",
+            [fix!(ShortWeekdayName), sp!(" "), fix!(ShortMonthName), sp!(" "),
+            num!(Day), sp!(" "), num!(Hour), lit!(":"), num!(Minute), lit!(":"),
+            num!(Second), sp!(" "), fix!(TimezoneName), sp!(" "), num!(Year)];
+            year: 2020, month: 8, day: 2, weekday: Weekday::Sun,
+            hour_div_12: 1, hour_mod_12: 1, minute: 39, second: 15);
     check!("20060102150405",
            [num!(Year), num!(Month), num!(Day), num!(Hour), num!(Minute), num!(Second)];
            year: 2006, month: 1, day: 2, hour_div_12: 1, hour_mod_12: 3, minute: 4, second: 5);
diff --git a/src/format/scan.rs b/src/format/scan.rs
index aef1de8c8e..0efb1ee3d1 100644
--- a/src/format/scan.rs
+++ b/src/format/scan.rs
@@ -342,3 +342,9 @@ pub fn timezone_offset_2822(s: &str) -> ParseResult<(&str, Option<i32>)> {
         Ok((s_, Some(offset)))
     }
 }
+
+/// Tries to consume everyting until next whitespace-like symbol.
+/// Does not provide any offset information from the consumed data.
+pub fn timezone_name_skip(s: &str) -> ParseResult<(&str, ())> {
+    Ok((s.trim_left_matches(|c: char| !c.is_whitespace()), ()))
+}
diff --git a/src/format/strftime.rs b/src/format/strftime.rs
index 0ca2ca9204..93820a2329 100644
--- a/src/format/strftime.rs
+++ b/src/format/strftime.rs
@@ -68,7 +68,7 @@ The following specifiers are available both to formatting and parsing.
 | `%r`  | `12:34:60 AM` | Hour-minute-second format in 12-hour clocks. Same as `%I:%M:%S %p`.   |
 |       |          |                                                                            |
 |       |          | **TIME ZONE SPECIFIERS:**                                                  |
-| `%Z`  | `ACST`   | *Formatting only:* Local time zone name.                                   |
+| `%Z`  | `ACST`   | Local time zone name. Skips all non-whitespace characters during parsing. [^9] |
 | `%z`  | `+0930`  | Offset from the local time to UTC (with UTC being `+0000`).                |
 | `%:z` | `+09:30` | Same as `%z` but with a colon.                                             |
 | `%#z` | `+09`    | *Parsing only:* Same as `%z` but allows minutes to be missing or present.  |
@@ -157,6 +157,15 @@ Notes:
    and parsing `07`, `070000` etc. will yield the same.
    Note that they can read nothing if the fractional part is zero.
 
+[^9]: `%Z`:
+   Offset will not be populated from the parsed data, nor will it be validated.
+   Timezone is completely ignored. Similar to the glibc `strptime` treatment of
+   this format code.
+   <br>
+   <br>
+   It is not possible to reliably convert from an abbreviation to an offset,
+   for example CDT can mean either Central Daylight Time (North America) or
+   China Daylight Time.
 */
 
 #[cfg(feature = "unstable-locales")]