refactor(options): use `const` in more places (#31791)

4 files changed, 26 insertions, 20 deletions

diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index 6504d44eb6..b9b5a055fb 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -872,11 +872,15 @@ static char *ex_let_option(char *arg, typval_T *const tv, const bool is_const,
       } else {
         newval = BOOLEAN_OPTVAL(TRISTATE_FROM_INT(new_n));
       }
-    } else if (!hidden && is_string
-               && curval.data.string.data != NULL && newval.data.string.data != NULL) {  // string
-      OptVal newval_old = newval;
-      newval = CSTR_AS_OPTVAL(concat_str(curval.data.string.data, newval.data.string.data));
-      optval_free(newval_old);
+    } else if (!hidden && is_string) {  // string
+      const char *curval_data = curval.data.string.data;
+      const char *newval_data = newval.data.string.data;
+
+      if (curval_data != NULL && newval_data != NULL) {
+        OptVal newval_old = newval;
+        newval = CSTR_AS_OPTVAL(concat_str(curval_data, newval_data));
+        optval_free(newval_old);
+      }
     }
   }
 
diff --git a/src/nvim/mapping.c b/src/nvim/mapping.c
index d29a2c8e43..ca0349d1f6 100644
--- a/src/nvim/mapping.c
+++ b/src/nvim/mapping.c
@@ -1901,7 +1901,7 @@ int makemap(FILE *fd, buf_T *buf)
 // "what": 0 for :map lhs, 1 for :map rhs, 2 for :set
 //
 // return FAIL for failure, OK otherwise
-int put_escstr(FILE *fd, char *strstart, int what)
+int put_escstr(FILE *fd, const char *strstart, int what)
 {
   uint8_t *str = (uint8_t *)strstart;
 
diff --git a/src/nvim/option.c b/src/nvim/option.c
index a59e55121f..9d9e70622a 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -533,8 +533,8 @@ static void set_string_default(OptIndex opt_idx, char *val, bool allocated)
 
 /// For an option value that contains comma separated items, find "newval" in
 /// "origval".  Return NULL if not found.
-static char *find_dup_item(char *origval, const char *newval, const size_t newvallen,
-                           uint32_t flags)
+static const char *find_dup_item(const char *origval, const char *newval, const size_t newvallen,
+                                 uint32_t flags)
   FUNC_ATTR_NONNULL_ARG(2)
 {
   if (origval == NULL) {
@@ -543,7 +543,7 @@ static char *find_dup_item(char *origval, const char *newval, const size_t newva
 
   int bs = 0;
 
-  for (char *s = origval; *s != NUL; s++) {
+  for (const char *s = origval; *s != NUL; s++) {
     if ((!(flags & kOptFlagComma) || s == origval || (s[-1] == ',' && !(bs & 1)))
         && strncmp(s, newval, newvallen) == 0
         && (!(flags & kOptFlagComma) || s[newvallen] == ',' || s[newvallen] == NUL)) {
@@ -727,7 +727,7 @@ void ex_set(exarg_T *eap)
 
 /// Copy the new string value into allocated memory for the option.
 /// Can't use set_option_direct(), because we need to remove the backslashes.
-static char *stropt_copy_value(char *origval, char **argp, set_op_T op,
+static char *stropt_copy_value(const char *origval, char **argp, set_op_T op,
                                uint32_t flags FUNC_ATTR_UNUSED)
 {
   char *arg = *argp;
@@ -774,7 +774,7 @@ static char *stropt_copy_value(char *origval, char **argp, set_op_T op,
 }
 
 /// Expand environment variables and ~ in string option value 'newval'.
-static char *stropt_expand_envvar(OptIndex opt_idx, char *origval, char *newval, set_op_T op)
+static char *stropt_expand_envvar(OptIndex opt_idx, const char *origval, char *newval, set_op_T op)
 {
   char *s = option_expand(opt_idx, newval);
   if (s == NULL) {
@@ -794,7 +794,7 @@ static char *stropt_expand_envvar(OptIndex opt_idx, char *origval, char *newval,
 
 /// Concatenate the original and new values of a string option, adding a "," if
 /// needed.
-static void stropt_concat_with_comma(char *origval, char *newval, set_op_T op, uint32_t flags)
+static void stropt_concat_with_comma(const char *origval, char *newval, set_op_T op, uint32_t flags)
 {
   int len = 0;
   int comma = ((flags & kOptFlagComma) && *origval != NUL && *newval != NUL);
@@ -820,7 +820,8 @@ static void stropt_concat_with_comma(char *origval, char *newval, set_op_T op, u
 
 /// Remove a value from a string option.  Copy string option value in "origval"
 /// to "newval" and then remove the string "strval" of length "len".
-static void stropt_remove_val(char *origval, char *newval, uint32_t flags, char *strval, int len)
+static void stropt_remove_val(const char *origval, char *newval, uint32_t flags, const char *strval,
+                              int len)
 {
   // Remove newval[] from origval[]. (Note: "len" has been set above
   // and is used here).
@@ -872,13 +873,13 @@ static void stropt_remove_dupflags(char *newval, uint32_t flags)
 ///     set {opt}={val}
 ///     set {opt}:{val}
 static char *stropt_get_newval(int nextchar, OptIndex opt_idx, char **argp, void *varp,
-                               char *origval, set_op_T *op_arg, uint32_t flags)
+                               const char *origval, set_op_T *op_arg, uint32_t flags)
 {
   char *arg = *argp;
   set_op_T op = *op_arg;
   char *save_arg = NULL;
   char *newval;
-  char *s = NULL;
+  const char *s = NULL;
 
   arg++;  // jump to after the '=' or ':'
 
@@ -1194,9 +1195,10 @@ static OptVal get_option_newval(OptIndex opt_idx, int opt_flags, set_prefix_T pr
     break;
   }
   case kOptValTypeString: {
-    char *oldval_str = oldval.data.string.data;
+    const char *oldval_str = oldval.data.string.data;
     // Get the new value for the option
-    char *newval_str = stropt_get_newval(nextchar, opt_idx, argp, varp, oldval_str, &op, flags);
+    const char *newval_str = stropt_get_newval(nextchar, opt_idx, argp, varp, oldval_str, &op,
+                                               flags);
     newval = CSTR_AS_OPTVAL(newval_str);
     break;
   }
@@ -1568,7 +1570,7 @@ char *find_shada_parameter(int type)
 /// These string options cannot be indirect!
 /// If "val" is NULL expand the current value of the option.
 /// Return pointer to NameBuff, or NULL when not expanded.
-static char *option_expand(OptIndex opt_idx, char *val)
+static char *option_expand(OptIndex opt_idx, const char *val)
 {
   // if option doesn't need expansion nothing to do
   if (!(options[opt_idx].flags & kOptFlagExpand) || is_option_hidden(opt_idx)) {
@@ -4392,7 +4394,7 @@ static int put_set(FILE *fd, char *cmd, OptIndex opt_idx, void *varp)
       return FAIL;
     }
 
-    char *value_str = value.data.string.data;
+    const char *value_str = value.data.string.data;
     char *buf = NULL;
     char *part = NULL;
 
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 733e52e69c..3126881266 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -580,7 +580,7 @@ void expand_env(char *src, char *dst, int dstlen)
 /// @param esc        Escape spaces in expanded variables
 /// @param one        `srcp` is a single filename
 /// @param prefix     Start again after this (can be NULL)
-void expand_env_esc(char *restrict srcp, char *restrict dst, int dstlen, bool esc, bool one,
+void expand_env_esc(const char *restrict srcp, char *restrict dst, int dstlen, bool esc, bool one,
                     char *prefix)
   FUNC_ATTR_NONNULL_ARG(1, 2)
 {