patch 8.2.2395: Vim9: error for wrong type may report wrong line number

Problem:    Vim9: error for wrong type may report wrong line number.
Solution:   Save and restore the line number when evaluating the expression.
            (closes #7727)

Author: brammool

src/evalvars.c

@@ -838,6 +838,8 @@ ex_let(exarg_T *eap)
 	i = FAIL;
 	if (has_assign || concat)
 	{
+	    int cur_lnum;
+
 	    op[0] = '=';
 	    op[1] = NUL;
 	    if (*expr != '=')
@@ -882,10 +884,15 @@ ex_let(exarg_T *eap)
 		evalarg.eval_cookie = eap->cookie;
 	    }
 	    expr = skipwhite_and_linebreak(expr, &evalarg);
+	    cur_lnum = SOURCING_LNUM;
 	    i = eval0(expr, &rettv, eap, &evalarg);
 	    if (eap->skip)
 		--emsg_skip;
 	    clear_evalarg(&evalarg, eap);
+
+	    // Restore the line number so that any type error is given for the
+	    // declaration, not the expression.
+	    SOURCING_LNUM = cur_lnum;
 	}
 	if (eap->skip)
 	{

src/testdir/test_vim9_assign.vim

@@ -55,6 +55,8 @@ def Test_assignment_bool()
   CheckDefAndScriptFailure(['var x: bool = [1]'], 'E1012:')
   CheckDefAndScriptFailure(['var x: bool = {}'], 'E1012:')
   CheckDefAndScriptFailure(['var x: bool = "x"'], 'E1012:')
+
+  CheckDefAndScriptFailure(['var x: bool = "x"', '', 'eval 0'], 'E1012:', 1)
 enddef
 
 def Test_syntax()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2395,
 /**/
     2394,
 /**/