# HG changeset patch
# User Bram Moolenaar <Bram@vim.org>
# Date 1541339106 -3600
# Node ID 0058cdd5b75210a1f7a0cc0915795ae6be32b831
# Parent  44cb79f534cd0aa7bee805039b4b628b040adf1d
patch 8.1.0510: filter test fails when $LANG is C.UTF-8

commit https://github.com/vim/vim/commit/dcd71cbaedf75dd8e5c5a45c5c2e3ec7ee552dce
Author: Bram Moolenaar <Bram@vim.org>
Date:   Sun Nov 4 14:40:47 2018 +0100

    patch 8.1.0510: filter test fails when $LANG is C.UTF-8

    Problem:    Filter test fails when $LANG is C.UTF-8.
    Solution:   Set 'helplang' to "en" for any C language. (Christian Brabandt,
                closes #3577)

diff --git a/src/option.c b/src/option.c
--- a/src/option.c
+++ b/src/option.c
@@ -4256,12 +4256,18 @@ set_helplang_default(char_u *lang)
 	    p_hlg = empty_option;
 	else
 	{
-	    /* zh_CN becomes "cn", zh_TW becomes "tw". */
+	    // zh_CN becomes "cn", zh_TW becomes "tw"
 	    if (STRNICMP(p_hlg, "zh_", 3) == 0 && STRLEN(p_hlg) >= 5)
 	    {
 		p_hlg[0] = TOLOWER_ASC(p_hlg[3]);
 		p_hlg[1] = TOLOWER_ASC(p_hlg[4]);
 	    }
+	    // any C like setting, such as C.UTF-8, becomes "en"
+	    else if (STRLEN(p_hlg) >= 1 && *p_hlg == 'C')
+	    {
+		p_hlg[0] = 'e';
+		p_hlg[1] = 'n';
+	    }
 	    p_hlg[2] = NUL;
 	}
 	options[idx].flags |= P_ALLOCED;
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    510,
+/**/
     509,
 /**/
     508,