Should nvm_auto not prefer current and .nvmrc versions of node to default alias?

[zeorin]

Currently, sourcing $NVM_DIR/nvm.sh after running nvm use will change the current version of node to the default alias, if set.
Sourcing $NVM_DIR/nvm.sh in a directory containing an .nvmrc will set the default alias, which I thought was surprising, since it will select the .nvmrc version if there's no default alias set.

The relevant code is:

#nvm.sh (lines 3539-3562)
nvm_auto() {
  nvm_echo "debug: nvm_auto"
  local NVM_MODE
  NVM_MODE="${1-}"
  local VERSION
  if [ "_$NVM_MODE" = '_install' ]; then
    VERSION="$(nvm_alias default 2>/dev/null || nvm_echo)"
    if [ -n "$VERSION" ]; then
      nvm install "$VERSION" >/dev/null
    elif nvm_rc_version >/dev/null 2>&1; then
      nvm install >/dev/null
    fi
  elif [ "_$NVM_MODE" = '_use' ]; then
    VERSION="$(nvm_resolve_local_alias default 2>/dev/null || nvm_echo)"
    if [ -n "$VERSION" ]; then
      nvm use --silent "$VERSION" >/dev/null
    elif nvm_rc_version >/dev/null 2>&1; then
      nvm use --silent >/dev/null
    fi
  elif [ "_$NVM_MODE" != '_none' ]; then
    nvm_err 'Invalid auto mode supplied.'
    return 1
  fi
}

I would expect the auto mode to prefer the current version (if any), then .nvmrc version to the default alias:

 nvm_auto() {
   local NVM_MODE
   NVM_MODE="${1-}"
-  local VERSION
+  local DEFAULT
+  local NVM_CURRENT
   if [ "_$NVM_MODE" = '_install' ]; then
-    VERSION="$(nvm_alias default 2>/dev/null || nvm_echo)"
-    if [ -n "$VERSION" ]; then
-      nvm install "$VERSION" >/dev/null
+    NVM_CURRENT="$(nvm_ls_current 2>/dev/null || nvm_echo)"
+    DEFAULT="$(nvm_alias default 2>/dev/null || nvm_echo)"
+    if [ "_$NVM_CURRENT" != "_$DEFAULT" ] && [ "_$NVM_CURRENT" != "_system" ]; then
+      nvm install "$NVM_CURRENT" >/dev/null
     elif nvm_rc_version >/dev/null 2>&1; then
       nvm install >/dev/null
+    elif [ -n "$DEFAULT" ]; then
+        nvm install "$DEFAULT" >/dev/null
     fi
   elif [ "_$NVM_MODE" = '_use' ]; then
-    VERSION="$(nvm_resolve_local_alias default 2>/dev/null || nvm_echo)"
-    if [ -n "$VERSION" ]; then
-      nvm use --silent "$VERSION" >/dev/null
+    NVM_CURRENT="$(nvm_ls_current 2>/dev/null || nvm_echo)"
+    DEFAULT="$(nvm_resolve_local_alias default 2>/dev/null || nvm_echo)"
+    if [ "_$NVM_CURRENT" != "_$DEFAULT" ] && [ "_$NVM_CURRENT" != "_system" ]; then
+      nvm use --silent "$NVM_CURRENT" >/dev/null
     elif nvm_rc_version >/dev/null 2>&1; then
       nvm use --silent >/dev/null
+    elif [ -n "$DEFAULT" ]; then
+      nvm use --silent "$DEFAULT" >/dev/null
     fi
   elif [ "_$NVM_MODE" != '_none' ]; then
     nvm_err 'Invalid auto mode supplied.'

This way, re-sourcing nvm will prefer the current version (if not system) or the .nvmrc version, or the default alias version.

[ljharb]

.nvmrc is a newer feature; at one point, auto-using selected the default only.

When .nvmrc was added, to avoid breaking auto-use behavior, default remained as the "winner" when both were set.

The current version is never preferred in a new shell - it'd always either be default, or nvmrc.

[zeorin]

Could we consider enabling the more intuitive (IMO) behaviour I'm suggesting if a flag (new env variable) were set? This would keep backwards compatibility.

[ljharb]

That would definitely be back compat - we could also use a sourcing flag - but I’m not sure the complexity is warranted, since you can unset the default and add a ~/.nvmrc containing the version you want as a fallback.

[zeorin]

It wouldn't solve a pain point for me that I haven't already solved in another way. The behaviour just surprised me, thanks for explaining!