From cf26173d18f782932829f001b95a27789850665f Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Tue, 4 Apr 2017 19:37:22 +0000
Subject: [PATCH] re PR go/80302 (FAIL: time on systems with tzdata2017b
 installed)

	PR go/80302
    time: make the ParseInLocation test more robust

    This is a backport of https://golang.org/cl/37964 from the gc toolchain.

    Original description:

        The tzdata 2017a update (2017-02-28) changed the abbreviation of the
        Asia/Baghdad time zone (used in TestParseInLocation) from 'AST' to the
        numeric '+03'.

        Update the test so that it skips the checks if we're using a recent
        tzdata release.

    Updates golang/go#19457
    Fixes GCC PR 80302.

    Reviewed-on: https://go-review.googlesource.com/39470

From-SVN: r246695
---
 libgo/go/time/format_test.go | 41 +++++++++++++++++++++++++++---------
 1 file changed, 31 insertions(+), 10 deletions(-)

diff --git a/libgo/go/time/format_test.go b/libgo/go/time/format_test.go
index 648ead0886c..0e4a4174309 100644
--- a/libgo/go/time/format_test.go
+++ b/libgo/go/time/format_test.go
@@ -245,27 +245,45 @@ func TestParseDayOutOfRange(t *testing.T) {
 	}
 }
 
+// TestParseInLocation checks that the Parse and ParseInLocation
+// functions do not get confused by the fact that AST (Arabia Standard
+// Time) and AST (Atlantic Standard Time) are different time zones,
+// even though they have the same abbreviation.
+//
+// ICANN has been slowly phasing out invented abbreviation in favor of
+// numeric time zones (for example, the Asia/Baghdad time zone
+// abbreviation got changed from AST to +03 in the 2017a tzdata
+// release); but we still want to make sure that the time package does
+// not get confused on systems with slightly older tzdata packages.
 func TestParseInLocation(t *testing.T) {
-	// Check that Parse (and ParseInLocation) understand that
-	// Feb 01 AST (Arabia Standard Time) and Feb 01 AST (Atlantic Standard Time)
-	// are in different time zones even though both are called AST
 
 	baghdad, err := LoadLocation("Asia/Baghdad")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	t1, err := ParseInLocation("Jan 02 2006 MST", "Feb 01 2013 AST", baghdad)
+	var t1, t2 Time
+
+	t1, err = ParseInLocation("Jan 02 2006 MST", "Feb 01 2013 AST", baghdad)
 	if err != nil {
 		t.Fatal(err)
 	}
-	t2 := Date(2013, February, 1, 00, 00, 00, 0, baghdad)
-	if t1 != t2 {
-		t.Fatalf("ParseInLocation(Feb 01 2013 AST, Baghdad) = %v, want %v", t1, t2)
-	}
+
 	_, offset := t1.Zone()
-	if offset != 3*60*60 {
-		t.Fatalf("ParseInLocation(Feb 01 2013 AST, Baghdad).Zone = _, %d, want _, %d", offset, 3*60*60)
+
+	// A zero offset means that ParseInLocation did not recognize the
+	// 'AST' abbreviation as matching the current location (Baghdad,
+	// where we'd expect a +03 hrs offset); likely because we're using
+	// a recent tzdata release (2017a or newer).
+	// If it happens, skip the Baghdad test.
+	if offset != 0 {
+		t2 = Date(2013, February, 1, 00, 00, 00, 0, baghdad)
+		if t1 != t2 {
+			t.Fatalf("ParseInLocation(Feb 01 2013 AST, Baghdad) = %v, want %v", t1, t2)
+		}
+		if offset != 3*60*60 {
+			t.Fatalf("ParseInLocation(Feb 01 2013 AST, Baghdad).Zone = _, %d, want _, %d", offset, 3*60*60)
+		}
 	}
 
 	blancSablon, err := LoadLocation("America/Blanc-Sablon")
@@ -273,6 +291,9 @@ func TestParseInLocation(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	// In this case 'AST' means 'Atlantic Standard Time', and we
+	// expect the abbreviation to correctly match the american
+	// location.
 	t1, err = ParseInLocation("Jan 02 2006 MST", "Feb 01 2013 AST", blancSablon)
 	if err != nil {
 		t.Fatal(err)
-- 
2.30.2