patch 8.2.4934: string interpolation fails when not evaluating
Problem: String interpolation fails when not evaluating.
Solution: Skip the expression when not evaluating. (closes #10398)
diff --git a/src/proto/evalvars.pro b/src/proto/evalvars.pro
index ce79435..4683c15 100644
--- a/src/proto/evalvars.pro
+++ b/src/proto/evalvars.pro
@@ -13,7 +13,7 @@
int get_spellword(list_T *list, char_u **pp);
void prepare_vimvar(int idx, typval_T *save_tv);
void restore_vimvar(int idx, typval_T *save_tv);
-char_u *eval_one_expr_in_str(char_u *p, garray_T *gap);
+char_u *eval_one_expr_in_str(char_u *p, garray_T *gap, int evaluate);
char_u *eval_all_expr_in_str(char_u *str);
list_T *heredoc_get(exarg_T *eap, char_u *cmd, int script_get, int vim9compile);
void ex_var(exarg_T *eap);