Make it easier to review Julia manifest updates (#2069)

This should put the output of `] update` and `status --outdated` in the
PR body, so we can easily see what changed and what is stuck.

Without this it looks like #1990.
With this it looks like
[#2070](#2070).

.github/workflows/julia_auto_update.yml

@@ -19,11 +19,13 @@ jobs:
         run: |
           pixi run install-julia
           pixi run update-manifest-julia
+        env:
+          JULIA_PKG_PRECOMPILE_AUTO: "0"
       - uses: peter-evans/create-pull-request@v7
         with:
           token: ${{ secrets.CI_PR_PAT }}
           branch: update/julia-manifest
           title: Update Julia manifest
           commit-message: "Update Julia manifest"
-          body: Update Julia dependencies to the latest version.
+          body-path: .pixi/update-manifest-julia.md
           author: "GitHub <noreply@github.com>"

pixi.toml

@@ -31,7 +31,7 @@ install = { depends-on = [
 # Julia
 # Clear SSL_CERT_DIR to avoid Julia warnings, see https://github.com/JuliaLang/Downloads.jl/issues/244
 update-registry-julia = { cmd = "julia --eval='using Pkg; Registry.update()'", env = { SSL_CERT_DIR = "" } }
-update-manifest-julia = { cmd = "julia --project --eval='using Pkg; Pkg.update()'", env = { SSL_CERT_DIR = "" } }
+update-manifest-julia = { cmd = "julia --project utils/update-manifest.jl", env = { SSL_CERT_DIR = "", JULIA_SSL_CA_ROOTS_PATH = "" } }
 instantiate-julia = { cmd = "julia --project --eval='using Pkg; Pkg.instantiate()'", env = { SSL_CERT_DIR = "", JULIA_SSL_CA_ROOTS_PATH = "" } }
 initialize-julia = { depends-on = [
     "update-registry-julia",

utils/update-manifest.jl

@@ -0,0 +1,47 @@
+import Pkg
+
+const IS_INSTALLED = r"\s*Installed (.+)"
+const DETAILS_BEGIN = """
+<details>
+<summary>
+All package versions
+</summary>
+
+```
+"""
+
+"""
+Update the Julia Manifest.toml and show the changes as well as outdated packages.
+The output is written to a file that can be used as the body of a pull request.
+"""
+function (@main)(_)
+    path = normpath(@__DIR__, "../.pixi/update-manifest-julia.md")
+    redirect_stdio(; stdout = path, stderr = path) do
+        println("Update the Julia Manifest.toml to get the latest dependencies.\n")
+        println("__Changed packages__\n```")
+        Pkg.update()
+        println("```\n\n__Packages still outdated after update__\n```")
+        Pkg.status(; outdated = true)
+        println("```")
+    end
+
+    # The Pkg.update output first prints all installed package versions.
+    # This is a lot, strip it out, sort it, and put it in a details tag at the end.
+    installed_lines = String[]
+    lines = readlines(path)
+    open(path, "w") do io
+        for line in lines
+            m = match(IS_INSTALLED, line)
+            if m === nothing
+                println(io, line)
+            else
+                push!(installed_lines, only(m.captures))
+            end
+        end
+
+        println(io, DETAILS_BEGIN)
+        sort!(installed_lines)
+        foreach(line -> println(io, line), installed_lines)
+        println("```\n\n</details>")
+    end
+end