[3.14] gh-124111: Update Windows build to use Tcl/Tk 9.0.4 (GH-150102) (GH-149477) (GH-151562) (GH-153901)

[zware]

(cherry picked from commit c62c371)

Keep tests passing for Tcl prior to 9.0 (GH-150102)

(cherry picked from commit ec9ce3e)

Co-Authored-By: Steve Dower steve.dower@python.org

• Issue: Update tkinter to use Tk 8.6.15 or (better) Tk 9.0 #124111

[zware]

To be kept in draft until declared ready to merge by @zooba and @hugovk. I'd like it to make the next patch release but it's not critical to do so, setting 'deferred blocker' just to keep it on the radar.

[hugovk]

Let's resolve #150836 first :)

[zware]

gh-150836 was resolved by GH-151562, which is now included here.

[ned-deily]

As of 2026-06-26, Tcl/Tk 9.0.4 is current.

[zware]

I'll start the process of getting main and 3.15 updated to that on the Windows side.

[encukou]

What's the plan with 9.0.4 on Python 3.14?

[hugovk]

To be kept in draft until declared ready to merge by @zooba and @hugovk. I'd like it to make the next patch release but it's not critical to do so, setting 'deferred blocker' just to keep it on the radar.

Let's resolve #150836 first :)

We've had it in 3.15 since b2. That issue was a bug in b2, fixed in b3, and b4 has since also come out, and it seems fine.

We already use Tck/Tk 9 in the macOS installer for both 3.14 and 3.15.

So I think we're ready to merge this for 3.14 as well.

[sethmlarson]

SBOM changes LGTM

[hugovk]

Just found this from the b4 logs:

WARNING  Failed to find TCL_LIBRARY

https://dev.azure.com/Python/cpython/_build/results?buildId=172790&view=results

Under:

"Generate layouts" > "Make layouts amd64 / amd64_t / etc" > "Generate full layout"

• https://dev.azure.com/Python/cpython/_build/results?buildId=172790&view=logs&j=0c103224-8ee8-5325-5df0-c5aaffd27de2&t=da04cdca-f3ae-566e-3a4e-e886757e530b
• etc

and:

"Generate layouts" > "Make PyManager layouts amd64 / amd64_t / etc" > "Generate PyManager layout"

• https://dev.azure.com/Python/cpython/_build/results?buildId=172790&view=logs&j=21b48d19-2bb7-580a-8430-2d680b69c0e0&t=c42b2406-2bbc-5122-71b8-53aee01081fb
• etc

---

Claude summary:

Windows release layouts silently ship without tcl\ under Tcl/Tk 9

The problem

The Windows release pipelines in python/release-tools hardcode
TCL_LIBRARY=<tcltk_lib artifact>\tcl8 before generating package layouts.
CPython's PC/layout script checks that path is a real directory, then copies
its parent (the whole Tcl/Tk lib artifact) into the package as tcl\.

• A Tcl 8.6 artifact contains a tcl8 directory, so this worked.
• A Tcl 9 artifact does not (its lib holds dde1.4, registry1.3, tk9.0,
  nmake, and the embedded-library zips libtcl9.0.4.zip/libtk9.0.4.zip),
  so the check fails, the layout script logs a non-fatal
  WARNING Failed to find TCL_LIBRARY, and silently ships without tcl\.

Evidence

• 3.15 is already affected — it has been on Tcl 9.0.4 since before b1.
  In build Release_v3.15.0b4_20260718.01
  (https://dev.azure.com/Python/cpython/_build/results?buildId=172790),
  stage "Generate layouts", the warning appears in all 15 tcltk-including
  layout jobs:

  • "Make layouts {amd64,arm64,win32}{,_t}" → step "Generate full layout"
  • "Make PyManager layouts {amd64,arm64,win32}{,_t,_test}" → step
    "Generate PyManager layout"

  Example log line ("Make PyManager layouts arm64"):

  2026-07-18T09:28:28.7088959Z WARNING  Failed to find TCL_LIBRARY
  

  The nuget/embeddable/*_embed jobs are unaffected because their layout
  presets don't include tcltk (PC/layout/support/options.py).

• Shipped packages confirm it: python-3.15.0b4-amd64.zip has zero
  tcl/ entries, vs. 1027 in python-3.14.2-amd64.zip (Tcl 8.6, same
  pipeline). Practical impact is modest — tkinter/IDLE still work because
  Tcl 9 embeds its script libraries in the DLLs (Tkinter not installed correctly on Windows 3.15.0b2 #150836) and
  tcl90.dll/tcl9tk90.dll/libtommath.dll are all present in DLLs/ —
  but the optional dde and registry Tcl packages are missing
  (package require dde/registry fails), diverging from the MSI installer,
  which is unaffected (msi-steps.yml passes the artifact root as
  TclTkLibraryDir and tcltk.wixproj harvests **\*).

• 3.14 will hit this too once this PR (the Tcl/Tk 9.0.4
  backport of gh-124111) merges and a release is cut. The tcltk build
  pipeline (tcltk-build.yml) was already updated for Tcl 9 in
  release-tools#378; only the layout stages were missed.

The fix

In windows-release/stage-layout-full.yml, stage-layout-msix.yml, and
stage-layout-pymanager.yml, the "Update TCL_LIBRARY" step now picks
whichever tcl*/tk* directory actually exists in the artifact and fails
the build loudly if none is found, so this can never silently regress again:

# PC\layout copies the *parent* of TCL_LIBRARY into the layout, so it only
# needs to name a directory that exists inside the artifact: tcl8 for
# Tcl 8.6, tk9.0 for Tcl 9 (which embeds its scripts in the DLL).
$tcl = Get-ChildItem "$(Pipeline.Workspace)\$(TclLibrary)" -Directory |
    Where-Object { $_.Name -match '^t(cl|k)\d' } | Select-Object -First 1
if (-not $tcl) {
    Write-Host "##[error]No Tcl/Tk library directory found in $(Pipeline.Workspace)\$(TclLibrary)"
    exit 1
}
Write-Host "##vso[task.setvariable variable=TCL_LIBRARY]$($tcl.FullName)"

Verified selection: tcl8 for an 8.6 artifact, tk9.0 for 9.0 — either
works since only the parent directory is used.

Also removed two per-step env: TCL_LIBRARY: $(TclLibrary) overrides in the
msix stage — a pre-existing bug that clobbered the correct path with the
artifact name (e.g. tcltk_lib_amd64) for the APPX layout steps.

[hugovk]

Possible fix at python/release-tools#424.