feat(env): remove VIM_VERSION_NODOT macro #34890

Problem:
- The VIM_VERSION_NODOT macro maintained support for legacy Vim
  version-specific runtime directories (e.g., "vim82") which I believe
  have never been relevant for Neovim

Solution:
- Remove it
- Rename `vim_version_dir()` to `vim_runtime_dir()`

runtime/doc/news.txt

@@ -303,6 +303,8 @@ These existing features changed their behavior.
 • 'spellfile' location defaults to `stdpath("data").."/site/spell/"` instead of
   the first writable directory in 'runtimepath'.
 • |vim.version.range()| doesn't exclude `to` if it is equal to `from`.
+• |$VIM| and |$VIMRUNTIME| no longer check for Vim version-specific runtime
+  directory `vim{number}` (e.g. `vim82`).
 • 'scrollback' maximum value increased from 100000 to 1000000
 
 ==============================================================================

runtime/doc/starting.txt

@@ -670,13 +670,11 @@ the main help file is normally "$VIMRUNTIME/doc/help.txt".
 Nvim will try to get the value for $VIMRUNTIME in this order:
 
 1. Environment variable $VIMRUNTIME, if it is set.
-2. Directory path "$VIM/vim{version}", if it exists, where {version} is the
+2. Directory path "$VIM/runtime", if it exists.
-   Vim version number without '-' or '.'.  For example: "$VIM/vim82".
+3. Value of $VIM environment variable.  This is for backwards compatibility
-3. Directory path "$VIM/runtime", if it exists.
-4. Value of $VIM environment variable.  This is for backwards compatibility
    with older Vim versions.
-5. If "../share/nvim/runtime" exists relative to |v:progpath|, it is used.
+4. If "../share/nvim/runtime" exists relative to |v:progpath|, it is used.
-6. Path derived from the 'helpfile' option (if it doesn't contain '$') with
+5. Path derived from the 'helpfile' option (if it doesn't contain '$') with
    "doc/help.txt" removed from the end.
 
 After doing this once, Nvim sets the $VIMRUNTIME environment variable.

src/nvim/os/env.c

@@ -781,20 +781,15 @@ size_t expand_env_esc(const char *restrict srcp, char *restrict dst, int dstlen,
   return (size_t)(dst - dst_start);
 }
 
-/// Check if the directory "vimdir/<version>" or "vimdir/runtime" exists.
+/// Check if the directory "vimdir/runtime" exists.
 /// Return NULL if not, return its name in allocated memory otherwise.
 /// @param vimdir directory to test
-static char *vim_version_dir(const char *vimdir)
+static char *vim_runtime_dir(const char *vimdir)
 {
   if (vimdir == NULL || *vimdir == NUL) {
     return NULL;
   }
-  char *p = concat_fnames(vimdir, VIM_VERSION_NODOT, true);
+  char *p = concat_fnames(vimdir, RUNTIME_DIRNAME, true);
-  if (os_isdir(p)) {
-    return p;
-  }
-  xfree(p);
-  p = concat_fnames(vimdir, RUNTIME_DIRNAME, true);
   if (os_isdir(p)) {
     return p;
   }
@@ -946,7 +941,7 @@ char *vim_getenv(const char *name)
       && *default_vimruntime_dir == NUL) {
     kos_env_path = os_getenv("VIM");    // kos_env_path was NULL.
     if (kos_env_path != NULL) {
-      vim_path = vim_version_dir(kos_env_path);
+      vim_path = vim_runtime_dir(kos_env_path);
       if (vim_path == NULL) {
         vim_path = kos_env_path;
       } else {
@@ -981,10 +976,9 @@ char *vim_getenv(const char *name)
         vim_path_end = remove_tail(vim_path, vim_path_end, "doc");
       }
 
-      // for $VIM, remove "runtime/" or "vim54/", if present
+      // for $VIM, remove "runtime/", if present
       if (!vimruntime) {
         vim_path_end = remove_tail(vim_path, vim_path_end, RUNTIME_DIRNAME);
-        vim_path_end = remove_tail(vim_path, vim_path_end, VIM_VERSION_NODOT);
       }
 
       // remove trailing path separator
@@ -1012,7 +1006,7 @@ char *vim_getenv(const char *name)
       vim_path = xstrdup(default_vimruntime_dir);
     } else if (*default_vim_dir != NUL) {
       if (vimruntime
-          && (vim_path = vim_version_dir(default_vim_dir)) == NULL) {
+          && (vim_path = vim_runtime_dir(default_vim_dir)) == NULL) {
         vim_path = xstrdup(default_vim_dir);
       }
     }

src/nvim/version.h

@@ -24,8 +24,6 @@ extern char *version_cflags;
 #define VIM_VERSION_MINOR_STR STR(VIM_VERSION_MINOR)
 #define VIM_VERSION_100     (VIM_VERSION_MAJOR * 100 + VIM_VERSION_MINOR)
 
-// used for the runtime directory name
-#define VIM_VERSION_NODOT "vim" VIM_VERSION_MAJOR_STR VIM_VERSION_MINOR_STR
 // swap file compatibility (max. length is 6 chars)
 #define VIM_VERSION_SHORT VIM_VERSION_MAJOR_STR "." VIM_VERSION_MINOR_STR