patch 8.1.0211: expanding a file name "~" results in $HOME

Problem:    Expanding a file name "~" results in $HOME. (Aidan Shafran)
Solution:   Change "~" to "./~" before expanding. (closes #3072)

src/eval.c

@@ -9690,11 +9690,12 @@ shortpath_for_partial(
  */
     int
 modify_fname(
-    char_u	*src,		/* string with modifiers */
+    char_u	*src,		// string with modifiers
-    int		*usedlen,	/* characters after src that are used */
+    int		tilde_file,	// "~" is a file name, not $HOME
-    char_u	**fnamep,	/* file name so far */
+    int		*usedlen,	// characters after src that are used
-    char_u	**bufp,		/* buffer for allocated file name or NULL */
+    char_u	**fnamep,	// file name so far
-    int		*fnamelen)	/* length of fnamep */
+    char_u	**bufp,		// buffer for allocated file name or NULL
+    int		*fnamelen)	// length of fnamep
 {
     int		valid = 0;
     char_u	*tail;
@@ -9724,8 +9725,8 @@ repeat:
 		    || (*fnamep)[1] == '\\'
 # endif
 		    || (*fnamep)[1] == NUL)
-
 #endif
+		&& !(tilde_file && (*fnamep)[1] == NUL)
 	   )
 	{
 	    *fnamep = expand_env_save(*fnamep);

src/evalfunc.c

@@ -3801,7 +3801,7 @@ f_fnamemodify(typval_T *argvars, typval_T *rettv)
     else
     {
 	len = (int)STRLEN(fname);
-	(void)modify_fname(mods, &usedlen, &fname, &fbuf, &len);
+	(void)modify_fname(mods, FALSE, &usedlen, &fname, &fbuf, &len);
     }
 
     rettv->v_type = VAR_STRING;

src/ex_docmd.c

@@ -10654,6 +10654,7 @@ eval_vars(
     int		resultlen;
     buf_T	*buf;
     int		valid = VALID_HEAD + VALID_PATH;    /* assume valid result */
+    int		tilde_file = FALSE;
     int		spec_idx;
 #ifdef FEAT_MODIFY_FNAME
     int		skip_mod = FALSE;
@@ -10720,7 +10721,10 @@ eval_vars(
 		    valid = 0;	    /* Must have ":p:h" to be valid */
 		}
 		else
+		{
 		    result = curbuf->b_fname;
+		    tilde_file = STRCMP(result, "~") == 0;
+		}
 		break;
 
 	case SPEC_HASH:		/* '#' or "#99": alternate file */
@@ -10784,7 +10788,10 @@ eval_vars(
 			valid = 0;	    /* Must have ":p:h" to be valid */
 		    }
 		    else
+		    {
 			result = buf->b_fname;
+			tilde_file = STRCMP(result, "~") == 0;
+		    }
 		}
 		break;
 
@@ -10877,7 +10884,7 @@ eval_vars(
 #ifdef FEAT_MODIFY_FNAME
 	else if (!skip_mod)
 	{
-	    valid |= modify_fname(src, usedlen, &result, &resultbuf,
+	    valid |= modify_fname(src, tilde_file, usedlen, &result, &resultbuf,
 								  &resultlen);
 	    if (result == NULL)
 	    {

src/if_cscope.c

@@ -519,7 +519,7 @@ cs_add_common(
 #ifdef FEAT_MODIFY_FNAME
     len = (int)STRLEN(fname);
     fbuf = (char_u *)fname;
-    (void)modify_fname((char_u *)":p", &usedlen,
+    (void)modify_fname((char_u *)":p", FALSE, &usedlen,
 					      (char_u **)&fname, &fbuf, &len);
     if (fname == NULL)
 	goto add_err;

src/misc1.c

@@ -4908,7 +4908,7 @@ home_replace(
 	char_u	*fbuf = NULL;
 
 	flen = (int)STRLEN(homedir_env);
-	(void)modify_fname((char_u *)":p", &usedlen,
+	(void)modify_fname((char_u *)":p", FALSE, &usedlen,
 						  &homedir_env, &fbuf, &flen);
 	flen = (int)STRLEN(homedir_env);
 	if (flen > 0 && vim_ispathsep(homedir_env[flen - 1]))

src/proto/eval.pro

@@ -136,7 +136,7 @@ void fill_assert_error(garray_T *gap, typval_T *opt_msg_tv, char_u *exp_str, typ
 int typval_compare(typval_T *typ1, typval_T *typ2, exptype_T type, int type_is, int ic);
 char_u *typval_tostring(typval_T *arg);
 int var_exists(char_u *var);
-int modify_fname(char_u *src, int *usedlen, char_u **fnamep, char_u **bufp, int *fnamelen);
+int modify_fname(char_u *src, int tilde_file, int *usedlen, char_u **fnamep, char_u **bufp, int *fnamelen);
 char_u *do_string_sub(char_u *str, char_u *pat, char_u *sub, typval_T *expr, char_u *flags);
 void filter_map(typval_T *argvars, typval_T *rettv, int map);
 /* vim: set ft=c : */

src/testdir/test_expand.vim

@@ -39,3 +39,11 @@ func Test_with_tilde()
   call delete('Xdir ~ dir', 'd')
   call assert_false(isdirectory('Xdir ~ dir'))
 endfunc
+
+func Test_expand_tilde_filename()
+  split ~
+  call assert_equal('~', expand('%')) 
+  call assert_notequal(expand('%:p'), expand('~/'))
+  call assert_match('\~', expand('%:p')) 
+  bwipe!
+endfunc

src/version.c

@@ -793,6 +793,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    211,
 /**/
     210,
 /**/