time: make month/day name comparisons case insenstive

Fixes #2324.

R=r, r
CC=golang-dev
https://golang.org/cl/5180044

src/pkg/time/format.go

@@ -232,9 +232,27 @@ var longMonthNames = []string{
 	"December",
 }
 
+// match returns true if s1 and s2 match ignoring case.
+// It is assumed s1 and s2 are the same length.
+func match(s1, s2 string) bool {
+	for i := 0; i < len(s1); i++ {
+		c1 := s1[i]
+		c2 := s2[i]
+		if c1 != c2 {
+			// Switch to lower-case; 'a'-'A' is known to be a single bit.
+			c1 |= 'a' - 'A'
+			c2 |= 'a' - 'A'
+			if c1 != c2 || c1 < 'a' || c1 > 'z' {
+				return false
+			}
+		}
+	}
+	return true
+}
+
 func lookup(tab []string, val string) (int, string, os.Error) {
 	for i, v := range tab {
-		if len(val) >= len(v) && val[0:len(v)] == v {
+		if len(val) >= len(v) && match(val[0:len(v)], v) {
 			return i, val[len(v):], nil
 		}
 	}

src/pkg/time/time_test.go

@@ -252,6 +252,9 @@ var parseTests = []ParseTest{
 	// Amount of white space should not matter.
 	{"ANSIC", ANSIC, "Thu Feb 4 21:00:57 2010", false, true, 1, 0},
 	{"ANSIC", ANSIC, "Thu      Feb     4     21:00:57     2010", false, true, 1, 0},
+	// Case should not matter
+	{"ANSIC", ANSIC, "THU FEB 4 21:00:57 2010", false, true, 1, 0},
+	{"ANSIC", ANSIC, "thu feb 4 21:00:57 2010", false, true, 1, 0},
 	// Fractional seconds.
 	{"millisecond", "Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 21:00:57.012 2010", false, true, 1, 3},
 	{"microsecond", "Mon Jan _2 15:04:05.000000 2006", "Thu Feb  4 21:00:57.012345 2010", false, true, 1, 6},