chore: add ./script/rebase-stage0.sh (#3984)

heavily based on an script by Kim.

doc/dev/bootstrap.md

@@ -84,10 +84,12 @@ gh workflow run update-stage0.yml
 Leaving stage0 updates to the CI automation is preferable, but should you need
 to do it locally, you can use `make update-stage0-commit` in `build/release` to
 update `stage0` from `stage1` or `make -C stageN update-stage0-commit` to
-update from another stage.
+update from another stage. This command will automatically stage the updated files
+and introduce a commit,so make sure to commit your work before that.
 
-This command will automatically stage the updated files and introduce a commit,
-so make sure to commit your work before that.
+If you rebased the branch (either onto a newer version of `master`, or fixing
+up some commits prior to the stage0 update, recreate the stage0 update commits.
+The script `script/rebase-stage0.sh` can be used for that.
 
 The CI should prevent PRs with changes to stage0 (besides `stdlib_flags.h`)
 from entering `master` through the (squashing!) merge queue, and label such PRs
@@ -95,6 +97,7 @@ with the `changes-stage0` label. Such PRs should have a cleaned up history,
 with separate stage0 update commits; then coordinate with the admins to merge
 your PR using rebase merge, bypassing the merge queue.
 
+
 ## Further Bootstrapping Complications
 
 As written above, changes in meta code in the current stage usually will only

nix/bootstrap.nix

@@ -180,7 +180,7 @@ rec {
       update-stage0 =
         let cTree = symlinkJoin { name = "cs"; paths = [ Init.cTree Lean.cTree ]; }; in
         writeShellScriptBin "update-stage0" ''
-          CSRCS=${cTree} CP_C_PARAMS="--dereference --no-preserve=all" ${src + "/script/update-stage0"}
+          CSRCS=${cTree} CP_C_PARAMS="--dereference --no-preserve=all" ${src + "/script/lib/update-stage0"}
         '';
       update-stage0-commit = writeShellScriptBin "update-stage0-commit" ''
         set -euo pipefail

script/lib/README.md

@@ -0,0 +1,2 @@
+This directory contains various scripts that are *not* meant to be called
+directly, but through other scripts or makefiles.

script/lib/rebase-editor.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+
+# Script internal to `./script/rebase-stage0.sh`
+
+# Determine OS type for sed in-place editing
+SED_CMD=("sed" "-i")
+if [[ "$OSTYPE" == "darwin"* ]]
+then
+    # macOS requires an empty string argument with -i for in-place editing
+    SED_CMD=("sed" "-i" "")
+fi
+
+if [ "$STAGE0_WITH_NIX" = true ]
+then
+  "${SED_CMD[@]}" '/chore: update stage0/ s,.*,x nix run .#update-stage0-commit,' "$1"
+else
+  "${SED_CMD[@]}" '/chore: update stage0/ s,.*,x make -j32 -C build/release update-stage0 \&\& git commit -m "chore: update stage0",' "$1"
+fi

script/rebase-stage0.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# This script rebases onto the given branch/commit, and updates
+# all `chore: update stage0` commits along the way.
+
+# Whether to use nix or make to update stage0
+if [ "$1" = "-nix" ]
+then
+   export STAGE0_WITH_NIX=true
+   shift
+fi
+
+# Check if an argument is provided
+if [ "$#" -eq 0 ]; then
+    echo "Usage: $0 [-nix] <options to git rebase -i>"
+    exit 1
+fi
+
+REPO_ROOT=$(git rev-parse --show-toplevel)
+
+# Run git rebase in interactive mode, but automatically edit the todo list
+# using the defined GIT_SEQUENCE_EDITOR command
+GIT_SEQUENCE_EDITOR="$REPO_ROOT/script/lib/rebase-editor.sh" git rebase -i "$@"
+

src/CMakeLists.txt

@@ -591,7 +591,7 @@ endif()
 
 if(PREV_STAGE)
   add_custom_target(update-stage0
-    COMMAND bash -c 'CSRCS=${CMAKE_BINARY_DIR}/lib/temp script/update-stage0'
+    COMMAND bash -c 'CSRCS=${CMAKE_BINARY_DIR}/lib/temp script/lib/update-stage0'
     DEPENDS make_stdlib
     WORKING_DIRECTORY "${LEAN_SOURCE_DIR}/..")