refactor: use S_LEN(s) instead of s, n (#29219)

42 files changed, 263 insertions, 258 deletions

diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index e5872fcc76..37aa946aaf 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -824,11 +824,11 @@ void do_autocmd(exarg_T *eap, char *arg_in, int forceit)
         continue;
       }
 
-      invalid_flags |= arg_autocmd_flag_get(&once, &cmd, "++once", 6);
-      invalid_flags |= arg_autocmd_flag_get(&nested, &cmd, "++nested", 8);
+      invalid_flags |= arg_autocmd_flag_get(&once, &cmd, S_LEN("++once"));
+      invalid_flags |= arg_autocmd_flag_get(&nested, &cmd, S_LEN("++nested"));
 
       // Check the deprecated "nested" flag.
-      invalid_flags |= arg_autocmd_flag_get(&nested, &cmd, "nested", 6);
+      invalid_flags |= arg_autocmd_flag_get(&nested, &cmd, S_LEN("nested"));
     }
 
     if (invalid_flags) {
@@ -1245,7 +1245,7 @@ void ex_doautoall(exarg_T *eap)
 bool check_nomodeline(char **argp)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  if (strncmp(*argp, "<nomodeline>", 12) == 0) {
+  if (strncmp(*argp, S_LEN("<nomodeline>")) == 0) {
     *argp = skipwhite(*argp + 12);
     return false;
   }
@@ -2359,7 +2359,7 @@ theend:
 bool aupat_is_buflocal(const char *pat, int patlen)
   FUNC_ATTR_PURE
 {
-  return patlen >= 8 && strncmp(pat, "<buffer", 7) == 0 && (pat)[patlen - 1] == '>';
+  return patlen >= 8 && strncmp(pat, S_LEN("<buffer")) == 0 && (pat)[patlen - 1] == '>';
 }
 
 int aupat_get_buflocal_nr(const char *pat, int patlen)
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 57245ce3f5..3f4e7047f9 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -3850,8 +3850,8 @@ static int chk_modeline(linenr_T lnum, int flags)
   int prev = -1;
   for (s = ml_get(lnum); *s != NUL; s++) {
     if (prev == -1 || ascii_isspace(prev)) {
-      if ((prev != -1 && strncmp(s, "ex:", 3) == 0)
-          || strncmp(s, "vi:", 3) == 0) {
+      if ((prev != -1 && strncmp(s, S_LEN("ex:")) == 0)
+          || strncmp(s, S_LEN("vi:")) == 0) {
         break;
       }
       // Accept both "vim" and "Vim".
@@ -3867,7 +3867,7 @@ static int chk_modeline(linenr_T lnum, int flags)
 
         if (*e == ':'
             && (s[0] != 'V'
-                || strncmp(skipwhite(e + 1), "set", 3) == 0)
+                || strncmp(skipwhite(e + 1), S_LEN("set")) == 0)
             && (s[3] == ':'
                 || (VIM_VERSION_100 >= vers && isdigit((uint8_t)s[3]))
                 || (VIM_VERSION_100 < vers && s[3] == '<')
@@ -3916,8 +3916,8 @@ static int chk_modeline(linenr_T lnum, int flags)
     // "vi:set opt opt opt: foo" -- foo not interpreted
     // "vi:opt opt opt: foo" -- foo interpreted
     // Accept "se" for compatibility with Elvis.
-    if (strncmp(s, "set ", 4) == 0
-        || strncmp(s, "se ", 3) == 0) {
+    if (strncmp(s, S_LEN("set ")) == 0
+        || strncmp(s, S_LEN("se ")) == 0) {
       if (*e != ':') {                // no terminating ':'?
         break;
       }
diff --git a/src/nvim/channel.c b/src/nvim/channel.c
index 5f9bfc3a73..e3df12abbe 100644
--- a/src/nvim/channel.c
+++ b/src/nvim/channel.c
@@ -639,7 +639,7 @@ static inline list_T *buffer_to_tv_list(const char *const buf, const size_t len)
   list_T *const l = tv_list_alloc(kListLenMayKnow);
   // Empty buffer should be represented by [''], encode_list_write() thinks
   // empty list is fine for the case.
-  tv_list_append_string(l, "", 0);
+  tv_list_append_string(l, S_LEN(""));
   if (len > 0) {
     encode_list_write(l, buf, len);
   }
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index 0b88e2be11..d8081ddfac 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -2247,7 +2247,7 @@ static const char *set_one_cmd_context(expand_T *xp, const char *buff)
 
   // Does command allow "++argopt" argument?
   if (ea.argt & EX_ARGOPT) {
-    while (*arg != NUL && strncmp(arg, "++", 2) == 0) {
+    while (*arg != NUL && strncmp(arg, S_LEN("++")) == 0) {
       p = arg + 2;
       while (*p && !ascii_isspace(*p)) {
         MB_PTR_ADV(p);
@@ -2774,7 +2774,7 @@ static int ExpandFromContext(expand_T *xp, char *pat, char ***matches, int *numM
   // When expanding a function name starting with s:, match the <SNR>nr_
   // prefix.
   char *tofree = NULL;
-  if (xp->xp_context == EXPAND_USER_FUNC && strncmp(pat, "^s:", 3) == 0) {
+  if (xp->xp_context == EXPAND_USER_FUNC && strncmp(pat, S_LEN("^s:")) == 0) {
     const size_t len = strlen(pat) + 20;
 
     tofree = xmalloc(len);
@@ -3564,7 +3564,7 @@ void f_getcompletion(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 
   if (xpc.xp_context == EXPAND_USER_DEFINED) {
     // Must be "custom,funcname" pattern
-    if (strncmp(type, "custom,", 7) != 0) {
+    if (strncmp(type, S_LEN("custom,")) != 0) {
       semsg(_(e_invarg2), type);
       return;
     }
@@ -3574,7 +3574,7 @@ void f_getcompletion(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 
   if (xpc.xp_context == EXPAND_USER_LIST) {
     // Must be "customlist,funcname" pattern
-    if (strncmp(type, "customlist,", 11) != 0) {
+    if (strncmp(type, S_LEN("customlist,")) != 0) {
       semsg(_(e_invarg2), type);
       return;
     }
diff --git a/src/nvim/context.c b/src/nvim/context.c
index 95e2618f62..b8eecfbb16 100644
--- a/src/nvim/context.c
+++ b/src/nvim/context.c
@@ -261,7 +261,7 @@ static inline void ctx_save_funcs(Context *ctx, bool scriptonly)
 
   HASHTAB_ITER(func_tbl_get(), hi, {
     const char *const name = hi->hi_key;
-    bool islambda = (strncmp(name, "<lambda>", 8) == 0);
+    bool islambda = (strncmp(name, S_LEN("<lambda>")) == 0);
     bool isscript = ((uint8_t)name[0] == K_SPECIAL);
 
     if (!islambda && (!scriptonly || isscript)) {
@@ -299,7 +299,7 @@ static inline void ctx_restore_funcs(Context *ctx)
 static inline Array sbuf_to_array(msgpack_sbuffer sbuf, Arena *arena)
 {
   list_T *const list = tv_list_alloc(kListLenMayKnow);
-  tv_list_append_string(list, "", 0);
+  tv_list_append_string(list, S_LEN(""));
   if (sbuf.size > 0) {
     encode_list_write(list, sbuf.data, sbuf.size);
   }
diff --git a/src/nvim/debugger.c b/src/nvim/debugger.c
index b71ff23f57..ffbeee7f7a 100644
--- a/src/nvim/debugger.c
+++ b/src/nvim/debugger.c
@@ -521,18 +521,18 @@ static int dbg_parsearg(char *arg, garray_T *gap)
   struct debuggy *bp = &DEBUGGY(gap, gap->ga_len);
 
   // Find "func" or "file".
-  if (strncmp(p, "func", 4) == 0) {
+  if (strncmp(p, S_LEN("func")) == 0) {
     bp->dbg_type = DBG_FUNC;
-  } else if (strncmp(p, "file", 4) == 0) {
+  } else if (strncmp(p, S_LEN("file")) == 0) {
     bp->dbg_type = DBG_FILE;
-  } else if (gap != &prof_ga && strncmp(p, "here", 4) == 0) {
+  } else if (gap != &prof_ga && strncmp(p, S_LEN("here")) == 0) {
     if (curbuf->b_ffname == NULL) {
       emsg(_(e_noname));
       return FAIL;
     }
     bp->dbg_type = DBG_FILE;
     here = true;
-  } else if (gap != &prof_ga && strncmp(p, "expr", 4) == 0) {
+  } else if (gap != &prof_ga && strncmp(p, S_LEN("expr")) == 0) {
     bp->dbg_type = DBG_EXPR;
   } else {
     semsg(_(e_invarg2), p);
@@ -559,7 +559,7 @@ static int dbg_parsearg(char *arg, garray_T *gap)
   }
 
   if (bp->dbg_type == DBG_FUNC) {
-    bp->dbg_name = xstrdup(strncmp(p, "g:", 2) == 0 ? p + 2 : p);
+    bp->dbg_name = xstrdup(strncmp(p, S_LEN("g:")) == 0 ? p + 2 : p);
   } else if (here) {
     bp->dbg_name = xstrdup(curbuf->b_ffname);
   } else if (bp->dbg_type == DBG_EXPR) {
diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 54335fc93e..e24c39e60c 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -1020,7 +1020,7 @@ static int check_external_diff(diffio_T *diffio)
     if (fd == NULL) {
       io_error = true;
     } else {
-      if (fwrite("line1\n", 6, 1, fd) != 1) {
+      if (fwrite(S_LEN("line1\n"), 1, fd) != 1) {
         io_error = true;
       }
       fclose(fd);
@@ -1029,7 +1029,7 @@ static int check_external_diff(diffio_T *diffio)
       if (fd == NULL) {
         io_error = true;
       } else {
-        if (fwrite("line2\n", 6, 1, fd) != 1) {
+        if (fwrite(S_LEN("line2\n"), 1, fd) != 1) {
           io_error = true;
         }
         fclose(fd);
@@ -1050,8 +1050,8 @@ static int check_external_diff(diffio_T *diffio)
               break;
             }
 
-            if (strncmp(linebuf, "1c1", 3) == 0
-                || strncmp(linebuf, "@@ -1 +1 @@", 11) == 0) {
+            if (strncmp(linebuf, S_LEN("1c1")) == 0
+                || strncmp(linebuf, S_LEN("@@ -1 +1 @@")) == 0) {
               ok = kTrue;
             }
           }
@@ -1583,13 +1583,13 @@ static bool extract_hunk(FILE *fd, diffhunk_T *hunk, diffstyle_T *diffstyle)
       // @@ -1,3 +1,5 @@
       if (isdigit((uint8_t)(*line))) {
         *diffstyle = DIFF_ED;
-      } else if ((strncmp(line, "@@ ", 3) == 0)) {
+      } else if ((strncmp(line, S_LEN("@@ ")) == 0)) {
         *diffstyle = DIFF_UNIFIED;
-      } else if ((strncmp(line, "--- ", 4) == 0)
+      } else if ((strncmp(line, S_LEN("--- ")) == 0)
                  && (vim_fgets(line, LBUFLEN, fd) == 0)
-                 && (strncmp(line, "+++ ", 4) == 0)
+                 && (strncmp(line, S_LEN("+++ ")) == 0)
                  && (vim_fgets(line, LBUFLEN, fd) == 0)
-                 && (strncmp(line, "@@ ", 3) == 0)) {
+                 && (strncmp(line, S_LEN("@@ ")) == 0)) {
         *diffstyle = DIFF_UNIFIED;
       } else {
         // Format not recognized yet, skip over this line.  Cygwin diff
@@ -1607,7 +1607,7 @@ static bool extract_hunk(FILE *fd, diffhunk_T *hunk, diffstyle_T *diffstyle)
       }
     } else {
       assert(*diffstyle == DIFF_UNIFIED);
-      if (strncmp(line, "@@ ", 3) != 0) {
+      if (strncmp(line, S_LEN("@@ ")) != 0) {
         continue;   // not the start of a diff block
       }
       if (parse_diff_unified(line, hunk) == FAIL) {
@@ -2473,70 +2473,70 @@ int diffopt_changed(void)
   char *p = p_dip;
   while (*p != NUL) {
     // Note: Keep this in sync with p_dip_values
-    if (strncmp(p, "filler", 6) == 0) {
+    if (strncmp(p, S_LEN("filler")) == 0) {
       p += 6;
       diff_flags_new |= DIFF_FILLER;
-    } else if ((strncmp(p, "context:", 8) == 0) && ascii_isdigit(p[8])) {
+    } else if ((strncmp(p, S_LEN("context:")) == 0) && ascii_isdigit(p[8])) {
       p += 8;
       diff_context_new = getdigits_int(&p, false, diff_context_new);
-    } else if (strncmp(p, "iblank", 6) == 0) {
+    } else if (strncmp(p, S_LEN("iblank")) == 0) {
       p += 6;
       diff_flags_new |= DIFF_IBLANK;
-    } else if (strncmp(p, "icase", 5) == 0) {
+    } else if (strncmp(p, S_LEN("icase")) == 0) {
       p += 5;
       diff_flags_new |= DIFF_ICASE;
-    } else if (strncmp(p, "iwhiteall", 9) == 0) {
+    } else if (strncmp(p, S_LEN("iwhiteall")) == 0) {
       p += 9;
       diff_flags_new |= DIFF_IWHITEALL;
-    } else if (strncmp(p, "iwhiteeol", 9) == 0) {
+    } else if (strncmp(p, S_LEN("iwhiteeol")) == 0) {
       p += 9;
       diff_flags_new |= DIFF_IWHITEEOL;
-    } else if (strncmp(p, "iwhite", 6) == 0) {
+    } else if (strncmp(p, S_LEN("iwhite")) == 0) {
       p += 6;
       diff_flags_new |= DIFF_IWHITE;
-    } else if (strncmp(p, "horizontal", 10) == 0) {
+    } else if (strncmp(p, S_LEN("horizontal")) == 0) {
       p += 10;
       diff_flags_new |= DIFF_HORIZONTAL;
-    } else if (strncmp(p, "vertical", 8) == 0) {
+    } else if (strncmp(p, S_LEN("vertical")) == 0) {
       p += 8;
       diff_flags_new |= DIFF_VERTICAL;
-    } else if ((strncmp(p, "foldcolumn:", 11) == 0) && ascii_isdigit(p[11])) {
+    } else if ((strncmp(p, S_LEN("foldcolumn:")) == 0) && ascii_isdigit(p[11])) {
       p += 11;
       diff_foldcolumn_new = getdigits_int(&p, false, diff_foldcolumn_new);
-    } else if (strncmp(p, "hiddenoff", 9) == 0) {
+    } else if (strncmp(p, S_LEN("hiddenoff")) == 0) {
       p += 9;
       diff_flags_new |= DIFF_HIDDEN_OFF;
-    } else if (strncmp(p, "closeoff", 8) == 0) {
+    } else if (strncmp(p, S_LEN("closeoff")) == 0) {
       p += 8;
       diff_flags_new |= DIFF_CLOSE_OFF;
-    } else if (strncmp(p, "followwrap", 10) == 0) {
+    } else if (strncmp(p, S_LEN("followwrap")) == 0) {
       p += 10;
       diff_flags_new |= DIFF_FOLLOWWRAP;
-    } else if (strncmp(p, "indent-heuristic", 16) == 0) {
+    } else if (strncmp(p, S_LEN("indent-heuristic")) == 0) {
       p += 16;
       diff_indent_heuristic = XDF_INDENT_HEURISTIC;
-    } else if (strncmp(p, "internal", 8) == 0) {
+    } else if (strncmp(p, S_LEN("internal")) == 0) {
       p += 8;
       diff_flags_new |= DIFF_INTERNAL;
-    } else if (strncmp(p, "algorithm:", 10) == 0) {
+    } else if (strncmp(p, S_LEN("algorithm:")) == 0) {
       // Note: Keep this in sync with p_dip_algorithm_values.
       p += 10;
-      if (strncmp(p, "myers", 5) == 0) {
+      if (strncmp(p, S_LEN("myers")) == 0) {
         p += 5;
         diff_algorithm_new = 0;
-      } else if (strncmp(p, "minimal", 7) == 0) {
+      } else if (strncmp(p, S_LEN("minimal")) == 0) {
         p += 7;
         diff_algorithm_new = XDF_NEED_MINIMAL;
-      } else if (strncmp(p, "patience", 8) == 0) {
+      } else if (strncmp(p, S_LEN("patience")) == 0) {
         p += 8;
         diff_algorithm_new = XDF_PATIENCE_DIFF;
-      } else if (strncmp(p, "histogram", 9) == 0) {
+      } else if (strncmp(p, S_LEN("histogram")) == 0) {
         p += 9;
         diff_algorithm_new = XDF_HISTOGRAM_DIFF;
       } else {
         return FAIL;
       }
-    } else if ((strncmp(p, "linematch:", 10) == 0) && ascii_isdigit(p[10])) {
+    } else if ((strncmp(p, S_LEN("linematch:")) == 0) && ascii_isdigit(p[10])) {
       p += 10;
       linematch_lines_new = getdigits_int(&p, false, linematch_lines_new);
       diff_flags_new |= DIFF_LINEMATCH;
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index f6e2dbfa4e..889f445c3d 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -3095,7 +3095,7 @@ bool in_cinkeys(int keytyped, int when, bool line_is_empty)
       if (try_match && keytyped == 'e' && curwin->w_cursor.col >= 4) {
         p = get_cursor_line_ptr();
         if (skipwhite(p) == p + curwin->w_cursor.col - 4
-            && strncmp(p + curwin->w_cursor.col - 4, "else", 4) == 0) {
+            && strncmp(p + curwin->w_cursor.col - 4, S_LEN("else")) == 0) {
           return true;
         }
       }
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index a4680b62ab..df5d336cbd 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -1219,7 +1219,7 @@ int call_vim_function(const char *func, int argc, typval_T *argv, typval_T *rett
   int len = (int)strlen(func);
   partial_T *pt = NULL;
 
-  if (len >= 6 && !memcmp(func, "v:lua.", 6)) {
+  if (len >= 6 && !memcmp(func, S_LEN("v:lua."))) {
     func += 6;
     len = check_luafunc_name(func, false);
     if (len == 0) {
@@ -2161,7 +2161,7 @@ void del_menutrans_vars(void)
 {
   hash_lock(&globvarht);
   HASHTAB_ITER(&globvarht, hi, {
-    if (strncmp(hi->hi_key, "menutrans_", 10) == 0) {
+    if (strncmp(hi->hi_key, S_LEN("menutrans_")) == 0) {
       delete_var(&globvarht, hi);
     }
   });
@@ -3274,7 +3274,7 @@ static int eval7(char **arg, typval_T *rettv, evalarg_T *const evalarg, bool wan
         check_vars(s, (size_t)len);
         // If evaluate is false rettv->v_type was not set, but it's needed
         // in handle_subscript() to parse v:lua, so set it here.
-        if (rettv->v_type == VAR_UNKNOWN && !evaluate && strnequal(s, "v:lua.", 6)) {
+        if (rettv->v_type == VAR_UNKNOWN && !evaluate && strnequal(s, S_LEN("v:lua."))) {
           rettv->v_type = VAR_PARTIAL;
           rettv->vval.v_partial = vvlua_partial;
           rettv->vval.v_partial->pt_refcount++;
@@ -3483,7 +3483,7 @@ static int eval_method(char **const arg, typval_T *const rettv, evalarg_T *const
   int len;
   char *name = *arg;
   char *lua_funcname = NULL;
-  if (strnequal(name, "v:lua.", 6)) {
+  if (strnequal(name, S_LEN("v:lua."))) {
     lua_funcname = name + 6;
     *arg = (char *)skip_luafunc_name(lua_funcname);
     *arg = skipwhite(*arg);  // to detect trailing whitespace later
@@ -5618,7 +5618,7 @@ void common_function(typval_T *argvars, typval_T *rettv, bool is_funcref)
     int dict_idx = 0;
     int arg_idx = 0;
     list_T *list = NULL;
-    if (strncmp(s, "s:", 2) == 0 || strncmp(s, "<SID>", 5) == 0) {
+    if (strncmp(s, S_LEN("s:")) == 0 || strncmp(s, S_LEN("<SID>")) == 0) {
       // Expand s: and <SID> into <SNR>nr_, so that the function can
       // also be called from another script. Using trans_function_name()
       // would also work, but some plugins depend on the name being
@@ -6192,7 +6192,7 @@ bool callback_call(Callback *const callback, const int argcount_in, typval_T *co
   case kCallbackFuncref:
     name = callback->data.funcref;
     int len = (int)strlen(name);
-    if (len >= 6 && !memcmp(name, "v:lua.", 6)) {
+    if (len >= 6 && !memcmp(name, S_LEN("v:lua."))) {
       name += 6;
       len = check_luafunc_name(name, false);
       if (len == 0) {
@@ -6460,7 +6460,7 @@ bool write_list(FileDescriptor *const fp, const list_T *const list, const bool b
       }
     }
     if (!binary || TV_LIST_ITEM_NEXT(list, li) != NULL) {
-      const ptrdiff_t written = file_write(fp, "\n", 1);
+      const ptrdiff_t written = file_write(fp, S_LEN("\n"));
       if (written < 0) {
         error = (int)written;
         goto write_list_error;
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 666d46cdad..9a1ed7dea9 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -5095,7 +5095,7 @@ static void get_matches_in_str(const char *str, regmatch_T *rmp, list_T *mlist,
       // return a list with the submatches
       for (int i = 1; i < NSUBEXP; i++) {
         if (rmp->endp[i] == NULL) {
-          tv_list_append_string(sml, "", 0);
+          tv_list_append_string(sml, S_LEN(""));
         } else {
           tv_list_append_string(sml, rmp->startp[i], rmp->endp[i] - rmp->startp[i]);
         }
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 2f7673a6f4..234ab59844 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -1360,11 +1360,11 @@ char *make_filter_cmd(char *cmd, char *itmp, char *otmp)
 {
   bool is_fish_shell =
 #if defined(UNIX)
-    strncmp(invocation_path_tail(p_sh, NULL), "fish", 4) == 0;
+    strncmp(invocation_path_tail(p_sh, NULL), S_LEN("fish")) == 0;
 #else
     false;
 #endif
-  bool is_pwsh = strncmp(invocation_path_tail(p_sh, NULL), "pwsh", 4) == 0
+  bool is_pwsh = strncmp(invocation_path_tail(p_sh, NULL), S_LEN("pwsh")) == 0
                  || strncmp(invocation_path_tail(p_sh, NULL), "powershell",
                             10) == 0;
 
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 1e2c515195..a38ff6333a 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -4191,7 +4191,7 @@ static int getargopt(exarg_T *eap)
   // Note: Keep this in sync with get_argopt_name.
 
   // ":edit ++[no]bin[ary] file"
-  if (strncmp(arg, "bin", 3) == 0 || strncmp(arg, "nobin", 5) == 0) {
+  if (strncmp(arg, S_LEN("bin")) == 0 || strncmp(arg, S_LEN("nobin")) == 0) {
     if (*arg == 'n') {
       arg += 2;
       eap->force_bin = FORCE_NOBIN;
@@ -4206,33 +4206,33 @@ static int getargopt(exarg_T *eap)
   }
 
   // ":read ++edit file"
-  if (strncmp(arg, "edit", 4) == 0) {
+  if (strncmp(arg, S_LEN("edit")) == 0) {
     eap->read_edit = true;
     eap->arg = skipwhite(arg + 4);
     return OK;
   }
 
   // ":write ++p foo/bar/file
-  if (strncmp(arg, "p", 1) == 0) {
+  if (strncmp(arg, S_LEN("p")) == 0) {
     eap->mkdir_p = true;
     eap->arg = skipwhite(arg + 1);
     return OK;
   }
 
-  if (strncmp(arg, "ff", 2) == 0) {
+  if (strncmp(arg, S_LEN("ff")) == 0) {
     arg += 2;
     pp = &eap->force_ff;
-  } else if (strncmp(arg, "fileformat", 10) == 0) {
+  } else if (strncmp(arg, S_LEN("fileformat")) == 0) {
     arg += 10;
     pp = &eap->force_ff;
-  } else if (strncmp(arg, "enc", 3) == 0) {
-    if (strncmp(arg, "encoding", 8) == 0) {
+  } else if (strncmp(arg, S_LEN("enc")) == 0) {
+    if (strncmp(arg, S_LEN("encoding")) == 0) {
       arg += 8;
     } else {
       arg += 3;
     }
     pp = &eap->force_enc;
-  } else if (strncmp(arg, "bad", 3) == 0) {
+  } else if (strncmp(arg, S_LEN("bad")) == 0) {
     arg += 3;
     pp = &bad_char_idx;
   }
@@ -4296,19 +4296,19 @@ int expand_argopt(char *pat, expand_T *xp, regmatch_T *rmp, char ***matches, int
 
     char *name_end = xp->xp_pattern - 1;
     if (name_end - xp->xp_line >= 2
-        && strncmp(name_end - 2, "ff", 2) == 0) {
+        && strncmp(name_end - 2, S_LEN("ff")) == 0) {
       cb = get_fileformat_name;
     } else if (name_end - xp->xp_line >= 10
-               && strncmp(name_end - 10, "fileformat", 10) == 0) {
+               && strncmp(name_end - 10, S_LEN("fileformat")) == 0) {
       cb = get_fileformat_name;
     } else if (name_end - xp->xp_line >= 3
-               && strncmp(name_end - 3, "enc", 3) == 0) {
+               && strncmp(name_end - 3, S_LEN("enc")) == 0) {
       cb = get_encoding_name;
     } else if (name_end - xp->xp_line >= 8
-               && strncmp(name_end - 8, "encoding", 8) == 0) {
+               && strncmp(name_end - 8, S_LEN("encoding")) == 0) {
       cb = get_encoding_name;
     } else if (name_end - xp->xp_line >= 3
-               && strncmp(name_end - 3, "bad", 3) == 0) {
+               && strncmp(name_end - 3, S_LEN("bad")) == 0) {
       cb = get_bad_name;
     }
 
@@ -7213,7 +7213,7 @@ char *expand_sfile(char *arg)
   char *result = xstrdup(arg);
 
   for (char *p = result; *p;) {
-    if (strncmp(p, "<sfile>", 7) != 0) {
+    if (strncmp(p, S_LEN("<sfile>")) != 0) {
       p++;
     } else {
       // replace "<sfile>" with the sourced file name, and do ":" stuff
@@ -7300,12 +7300,12 @@ static void ex_filetype(exarg_T *eap)
 
   // Accept "plugin" and "indent" in any order.
   while (true) {
-    if (strncmp(arg, "plugin", 6) == 0) {
+    if (strncmp(arg, S_LEN("plugin")) == 0) {
       plugin = true;
       arg = skipwhite(arg + 6);
       continue;
     }
-    if (strncmp(arg, "indent", 6) == 0) {
+    if (strncmp(arg, S_LEN("indent")) == 0) {
       indent = true;
       arg = skipwhite(arg + 6);
       continue;
@@ -7384,7 +7384,7 @@ static void ex_setfiletype(exarg_T *eap)
   }
 
   char *arg = eap->arg;
-  if (strncmp(arg, "FALLBACK ", 9) == 0) {
+  if (strncmp(arg, S_LEN("FALLBACK ")) == 0) {
     arg += 9;
   }
 
diff --git a/src/nvim/ex_eval.c b/src/nvim/ex_eval.c
index 2681beb228..0b2e1f9294 100644
--- a/src/nvim/ex_eval.c
+++ b/src/nvim/ex_eval.c
@@ -254,7 +254,7 @@ bool cause_errthrow(const char *mesg, bool multiline, bool severe, bool *ignore)
       if (plist == msg_list || severe) {
         // Skip the extra "Vim " prefix for message "E458".
         char *tmsg = elem->msg;
-        if (strncmp(tmsg, "Vim E", 5) == 0
+        if (strncmp(tmsg, S_LEN("Vim E")) == 0
             && ascii_isdigit(tmsg[5])
             && ascii_isdigit(tmsg[6])
             && ascii_isdigit(tmsg[7])
@@ -443,7 +443,7 @@ static int throw_exception(void *value, except_type_T type, char *cmdname)
   // would be treated differently from real interrupt or error exceptions
   // when no active try block is found, see do_cmdline().
   if (type == ET_USER) {
-    if (strncmp(value, "Vim", 3) == 0
+    if (strncmp(value, S_LEN("Vim")) == 0
         && (((char *)value)[3] == NUL || ((char *)value)[3] == ':'
             || ((char *)value)[3] == '(')) {
       emsg(_("E608: Cannot :throw exceptions with 'Vim' prefix"));
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index cef1868fc8..74e6e3422e 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -2799,13 +2799,13 @@ int check_opt_wim(void)
     if (p[i] != NUL && p[i] != ',' && p[i] != ':') {
       return FAIL;
     }
-    if (i == 7 && strncmp(p, "longest", 7) == 0) {
+    if (i == 7 && strncmp(p, S_LEN("longest")) == 0) {
       new_wim_flags[idx] |= WIM_LONGEST;
-    } else if (i == 4 && strncmp(p, "full", 4) == 0) {
+    } else if (i == 4 && strncmp(p, S_LEN("full")) == 0) {
       new_wim_flags[idx] |= WIM_FULL;
-    } else if (i == 4 && strncmp(p, "list", 4) == 0) {
+    } else if (i == 4 && strncmp(p, S_LEN("list")) == 0) {
       new_wim_flags[idx] |= WIM_LIST;
-    } else if (i == 8 && strncmp(p, "lastused", 8) == 0) {
+    } else if (i == 8 && strncmp(p, S_LEN("lastused")) == 0) {
       new_wim_flags[idx] |= WIM_BUFLASTUSED;
     } else {
       return FAIL;
diff --git a/src/nvim/file_search.c b/src/nvim/file_search.c
index 30a80773e3..ef936abab5 100644
--- a/src/nvim/file_search.c
+++ b/src/nvim/file_search.c
@@ -399,7 +399,7 @@ void *vim_findfile_init(char *path, char *filename, char *stopdirs, int level, i
         emsg(_(e_path_too_long_for_completion));
         break;
       }
-      if (strncmp(wc_part, "**", 2) == 0) {
+      if (strncmp(wc_part, S_LEN("**")) == 0) {
         ff_expand_buffer[len++] = *wc_part++;
         ff_expand_buffer[len++] = *wc_part++;
 
@@