patch 8.2.2912: MS-Windows: most users expect using Unicode

Problem:    MS-Windows: most users expect using Unicode.
Solution:   Default 'encoding' to utf-8 on MS-Windows. (Ken Takata,
            closes #3907)

runtime/doc/options.txt

@@ -2828,7 +2828,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	|setcellwidths()| function to change the behavior.
 
 					*'encoding'* *'enc'* *E543*
-'encoding' 'enc'	string (default: "latin1" or value from $LANG)
+'encoding' 'enc'	string (default for MS-Windows: "utf-8",
+				otherwise: value from $LANG or "latin1")
 			global
 	Sets the character encoding used inside Vim.  It applies to text in
 	the buffers, registers, Strings in expressions, text stored in the

src/mbyte.c

@@ -4456,7 +4456,7 @@ enc_canonize(char_u *enc)
 	// Use the default encoding as it's found by set_init_1().
 	r = get_encoding_default();
 	if (r == NULL)
-	    r = (char_u *)"latin1";
+	    r = (char_u *)ENC_DFLT;
 	return vim_strsave(r);
     }
 

src/option.c

@@ -430,14 +430,21 @@ set_init_1(int clean_arg)
 #  endif
 # endif
 
+# ifdef MSWIN
+    // MS-Windows has builtin support for conversion to and from Unicode, using
+    // "utf-8" for 'encoding' should work best for most users.
+    p = vim_strsave((char_u *)ENC_DFLT);
+# else
     // enc_locale() will try to find the encoding of the current locale.
+    // This works best for properly configured systems, old and new.
     p = enc_locale();
+# endif
     if (p != NULL)
     {
 	char_u *save_enc;
 
 	// Try setting 'encoding' and check if the value is valid.
-	// If not, go back to the default "latin1".
+	// If not, go back to the default encoding.
 	save_enc = p_enc;
 	p_enc = p;
 	if (STRCMP(p_enc, "gb18030") == 0)

src/option.h

@@ -127,7 +127,11 @@ typedef enum {
 #define ENC_UCSBOM	"ucs-bom"	// check for BOM at start of file
 
 // default value for 'encoding'
-#define ENC_DFLT	"latin1"
+#ifdef MSWIN
+# define ENC_DFLT	"utf-8"
+#else
+# define ENC_DFLT	"latin1"
+#endif
 
 // end-of-line style
 #define EOL_UNKNOWN	-1	// not defined yet

src/testdir/test_writefile.vim

@@ -501,7 +501,7 @@ func Test_write_file_encoding()
   CheckMSWindows
   let save_encoding = &encoding
   let save_fileencodings = &fileencodings
-  set encoding& fileencodings&
+  set encoding=latin1 fileencodings&
   let text =<< trim END
     1 utf-8 text: Для Vim version 6.2.  Последнее изменение: 1970 Jan 01
     2 cp1251 text: Äëÿ Vim version 6.2.  Ïîñëåäíåå èçìåíåíèå: 1970 Jan 01

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2912,
 /**/
     2911,
 /**/