scripts/vim-patch.sh: lazily update Vim source (#11207)

This gets done only initially, for `-l`, and when a commit cannot be found.

Also provide more compact instructions with `-l` / `show_vimpatches`.

scripts/vim-patch.sh

@@ -89,7 +89,7 @@ get_vim_sources() {
     echo "Cloning Vim into: ${VIM_SOURCE_DIR}"
     git clone https://github.com/vim/vim.git "${VIM_SOURCE_DIR}"
     cd "${VIM_SOURCE_DIR}"
-  else
+  elif [[ "${1-}" == update ]]; then
     cd "${VIM_SOURCE_DIR}"
     if ! [ -d ".git" ] \
         && ! [ "$(git rev-parse --show-toplevel)" = "${VIM_SOURCE_DIR}" ]; then
@@ -103,6 +103,8 @@ get_vim_sources() {
     else
       msg_err "Could not update Vim sources; ignoring error."
     fi
+  else
+    cd "${VIM_SOURCE_DIR}"
   fi
 }
 
@@ -124,7 +126,7 @@ find_git_remote() {
 }
 
 # Assign variables for a given Vim tag, patch version, or commit.
-# Might exit in case it cannot be found.
+# Might exit in case it cannot be found, after updating Vim sources.
 assign_commit_details() {
   local vim_commit_ref
   if [[ ${1} =~ v?[0-9]\.[0-9]\.[0-9]{3,4} ]]; then
@@ -146,9 +148,14 @@ assign_commit_details() {
     local munge_commit_line=false
   fi
 
-  vim_commit=$(git -C "${VIM_SOURCE_DIR}" log -1 --format="%H" "${vim_commit_ref}" --) || {
+  local get_vim_commit_cmd="git -C ${VIM_SOURCE_DIR} log -1 --format=%H ${vim_commit_ref} --"
-    >&2 msg_err "Couldn't find Vim revision '${vim_commit_ref}'."
+  vim_commit=$($get_vim_commit_cmd 2>&1) || {
-    exit 3
+    # Update Vim sources.
+    get_vim_sources update
+    vim_commit=$($get_vim_commit_cmd 2>&1) || {
+      >&2 msg_err "Couldn't find Vim revision '${vim_commit_ref}': git error: ${vim_commit}."
+      exit 3
+    }
   }
 
   vim_commit_url="https://github.com/vim/vim/commit/${vim_commit}"
@@ -478,8 +485,8 @@ list_missing_vimpatches() {
 # Prints a human-formatted list of Vim commits, with instructional messages.
 # Passes "$@" onto list_missing_vimpatches (args for git-log).
 show_vimpatches() {
-  get_vim_sources
+  get_vim_sources update
-  printf "\nVim patches missing from Neovim:\n"
+  printf "Vim patches missing from Neovim:\n"
 
   local -A runtime_commits
   for commit in $(git -C "${VIM_SOURCE_DIR}" log --format="%H %D" -- runtime | sed 's/,\? tag: / /g'); do
@@ -494,17 +501,12 @@ show_vimpatches() {
     fi
   done
 
-  printf "Instructions:
+  printf "\nInstructions:
-
+  To port one of the above patches to Neovim, execute this script with the patch revision as argument and follow the instructions, e.g.
-  To port one of the above patches to Neovim, execute
+  '%s -p v8.0.1234', or '%s -P v8.0.1234'
-  this script with the patch revision as argument and
-  follow the instructions.
-
-  Examples: '%s -p 7.4.487'
-            '%s -p 1e8ebf870720e7b671f98f22d653009826304c4f'
 
   NOTE: Please port the _oldest_ patch if you possibly can.
-        Out-of-order patches increase the possibility of bugs.
+        You can use '%s -l path/to/file' to see what patches are missing for a file.
 " "${BASENAME}" "${BASENAME}"
 }
 
@@ -646,7 +648,7 @@ while getopts "hlLMVp:P:g:r:s" opt; do
       exit 0
       ;;
     V)
-      get_vim_sources
+      get_vim_sources update
       exit 0
       ;;
     *)