From 845306393697b2ba3c9db7b2b388a9402586f629 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 26 Feb 2026 16:41:43 +0100
Subject: [PATCH 1/8] support optionally building AMD64 with tailcalling

---
 windows-release/azure-pipelines.yml | 6 +++++-
 windows-release/stage-build.yml     | 9 +++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/windows-release/azure-pipelines.yml b/windows-release/azure-pipelines.yml
index 20335a9f..be133b49 100644
--- a/windows-release/azure-pipelines.yml
+++ b/windows-release/azure-pipelines.yml
@@ -42,6 +42,10 @@ parameters:
   displayName: "Signature description"
   type: string
   default: '(default)'
+- name: DoTailcalling
+  displayName: "Build AMD64 with tailcalling support (3.15 and later)"
+  type: boolean
+  default: false
 - name: DoJIT
   displayName: "Build the JIT compiler (3.14 and later)"
   type: boolean
@@ -161,7 +165,7 @@ stages:
   - stage: Build
     displayName: Build binaries
     pool:
-      vmImage: ${{ parameters.vmImage }}
+      vmImage: ${{ if eq(parameters.DoTailcalling, 'true') }} 'windows-2025-vs2026' ${{ else }} ${{ parameters.vmImage }}
     jobs:
     - template: start-arm64vm.yml
       parameters:
diff --git a/windows-release/stage-build.yml b/windows-release/stage-build.yml
index 350a30a1..f3bb0aa3 100644
--- a/windows-release/stage-build.yml
+++ b/windows-release/stage-build.yml
@@ -4,6 +4,7 @@ parameters:
   DoPGOARM64: true
   DoFreethreaded: false
   ToBeSigned: false
+  DoTailcalling: false
   ExtraOptions: ''
   ExtraOptionsFreethreaded: '--disable-gil'
 
@@ -71,7 +72,7 @@ jobs:
           Platform: x64
           Configuration: Release
           _HostPython: .\python
-          ExtraOptions: ${{ parameters.ExtraOptions }}
+          ExtraOptions: ${{ parameters.ExtraOptions }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -131,7 +132,7 @@ jobs:
             Platform: x64
             Configuration: Release
             _HostPython: .\python
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:
@@ -185,7 +186,7 @@ jobs:
           Platform: x64
           _HostPython: .\python
           PythonExePattern: python.exe
-          ExtraOptions: ${{ parameters.ExtraOptions }}
+          ExtraOptions: ${{ parameters.ExtraOptions }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -197,7 +198,7 @@ jobs:
             Platform: x64
             _HostPython: .\python
             PythonExePattern: python3*t.exe
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:

From c49abd88ee1e0ae4495fdafe109aa90539fee1ff Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 26 Feb 2026 18:53:45 +0100
Subject: [PATCH 2/8] apply Steve's fix

---
 windows-release/azure-pipelines.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/windows-release/azure-pipelines.yml b/windows-release/azure-pipelines.yml
index be133b49..efad271b 100644
--- a/windows-release/azure-pipelines.yml
+++ b/windows-release/azure-pipelines.yml
@@ -165,7 +165,7 @@ stages:
   - stage: Build
     displayName: Build binaries
     pool:
-      vmImage: ${{ if eq(parameters.DoTailcalling, 'true') }} 'windows-2025-vs2026' ${{ else }} ${{ parameters.vmImage }}
+      vmImage: ${{ if(eq(parameters.DoTailcalling, 'true'), 'windows-2025-vs2026', parameters.vmImage) }}
     jobs:
     - template: start-arm64vm.yml
       parameters:

From 7abd79b0e78bc2911dfc6773b6d8f3f010de5391 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 26 Feb 2026 19:11:57 +0100
Subject: [PATCH 3/8] Different approach. Does this work out?

---
 windows-release/azure-pipelines.yml |  5 ++++-
 windows-release/build-steps-pgo.yml |  4 ++--
 windows-release/build-steps.yml     |  4 ++--
 windows-release/stage-build.yml     | 24 +++++++++++++++++++-----
 4 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/windows-release/azure-pipelines.yml b/windows-release/azure-pipelines.yml
index efad271b..b58a2b8a 100644
--- a/windows-release/azure-pipelines.yml
+++ b/windows-release/azure-pipelines.yml
@@ -190,7 +190,10 @@ stages:
           ExtraOptionsFreethreaded: '--disable-gil --experimental-jit-off'
         ${{ else }}:
           ExtraOptionsFreethreaded: '--disable-gil --experimental-jit'
-
+        ${{ if ne(parameters.DoTailcalling, 'true') }}:
+          TailcallingOption: ''
+        ${{ else }}:
+          TailcallingOption: '--tail-call-interp'
   - stage: Sign
     displayName: Sign binaries
     dependsOn: Build
diff --git a/windows-release/build-steps-pgo.yml b/windows-release/build-steps-pgo.yml
index f55ec42c..2195285a 100644
--- a/windows-release/build-steps-pgo.yml
+++ b/windows-release/build-steps-pgo.yml
@@ -22,7 +22,7 @@ steps:
 - ${{ if eq(parameters.PGInstrument, 'true') }}:
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) -c PGInstrument $(ExtraOptions)
+      .\PCbuild\build.bat -v -p $(Platform) -c PGInstrument $(ExtraOptions) $(TailcallingOption)
     displayName: 'Run build'
     env:
       IncludeUwp: true
@@ -100,7 +100,7 @@ steps:
 
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) -c PGUpdate $(ExtraOptions)
+      .\PCbuild\build.bat -v -p $(Platform) -c PGUpdate $(ExtraOptions) $(TailcallingOption)
     displayName: 'Run build with PGO'
     env:
       IncludeUwp: true
diff --git a/windows-release/build-steps.yml b/windows-release/build-steps.yml
index 300d7e79..a62f3a22 100644
--- a/windows-release/build-steps.yml
+++ b/windows-release/build-steps.yml
@@ -18,7 +18,7 @@ steps:
 - ${{ if eq(parameters.ShouldPGO, 'false') }}:
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) -c $(Configuration) $(ExtraOptions)
+      .\PCbuild\build.bat -v -p $(Platform) -c $(Configuration) $(ExtraOptions) $(TailcallingOption)
     displayName: 'Run build'
     env:
       IncludeUwp: true
@@ -27,7 +27,7 @@ steps:
 - ${{ else }}:
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) --pgo $(ExtraOptions)
+      .\PCbuild\build.bat -v -p $(Platform) --pgo $(ExtraOptions) $(TailcallingOption)
     displayName: 'Run build with PGO'
     env:
       IncludeUwp: true
diff --git a/windows-release/stage-build.yml b/windows-release/stage-build.yml
index f3bb0aa3..82fa5368 100644
--- a/windows-release/stage-build.yml
+++ b/windows-release/stage-build.yml
@@ -4,9 +4,9 @@ parameters:
   DoPGOARM64: true
   DoFreethreaded: false
   ToBeSigned: false
-  DoTailcalling: false
   ExtraOptions: ''
   ExtraOptionsFreethreaded: '--disable-gil'
+  TailcallingOption: ''
 
 jobs:
 - job: Build_Docs
@@ -53,6 +53,7 @@ jobs:
         Configuration: Release
         _HostPython: .\python
         ExtraOptions: ${{ parameters.ExtraOptions }}
+        TailcallingOption: ''
         ${{ if eq(parameters.ToBeSigned, 'true') }}:
           Artifact: unsigned_win32
         ${{ else }}:
@@ -64,6 +65,7 @@ jobs:
         Configuration: Debug
         _HostPython: .\python
         ExtraOptions: ${{ parameters.ExtraOptions }}
+        TailcallingOption: ''
         Artifact: bin_win32_d
       ${{ if ne(parameters.DoPGO, 'true') }}:
         amd64:
@@ -72,7 +74,8 @@ jobs:
           Platform: x64
           Configuration: Release
           _HostPython: .\python
-          ExtraOptions: ${{ parameters.ExtraOptions }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
+          ExtraOptions: ${{ parameters.ExtraOptions }}
+          TailcallingOption: ${{ parameters.TailcallingOption }}
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -84,6 +87,7 @@ jobs:
         Configuration: Debug
         _HostPython: .\python
         ExtraOptions: ${{ parameters.ExtraOptions }}
+        TailcallingOption: ''
         Artifact: bin_amd64_d
       ${{ if or(ne(parameters.DoPGO, 'true'), ne(parameters.DoPGOARM64, 'true')) }}:
         arm64:
@@ -93,6 +97,7 @@ jobs:
           Configuration: Release
           _HostPython: python
           ExtraOptions: ${{ parameters.ExtraOptions }}
+          TailcallingOption: ''
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_arm64
           ${{ else }}:
@@ -104,6 +109,7 @@ jobs:
         Configuration: Debug
         _HostPython: python
         ExtraOptions: ${{ parameters.ExtraOptions }}
+        TailcallingOption: ''
         Artifact: bin_arm64_d
       ${{ if eq(parameters.DoFreethreaded, 'true') }}:
         win32_t:
@@ -113,6 +119,7 @@ jobs:
           Configuration: Release
           _HostPython: .\python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+          TailcallingOption: ''
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_win32_t
           ${{ else }}:
@@ -124,6 +131,7 @@ jobs:
           Configuration: Debug
           _HostPython: .\python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+          TailcallingOption: ''
           Artifact: bin_win32_td
         ${{ if ne(parameters.DoPGO, 'true') }}:
           amd64_t:
@@ -132,7 +140,8 @@ jobs:
             Platform: x64
             Configuration: Release
             _HostPython: .\python
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+            TailcallingOption: ${{ parameters.TailcallingOption }}
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:
@@ -144,6 +153,7 @@ jobs:
           Configuration: Debug
           _HostPython: .\python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+          TailcallingOption: ''
           Artifact: bin_amd64_td
         ${{ if or(ne(parameters.DoPGO, 'true'), ne(parameters.DoPGOARM64, 'true')) }}:
           arm64_t:
@@ -153,6 +163,7 @@ jobs:
             Configuration: Release
             _HostPython: python
             ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+            TailcallingOption: ''
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_arm64_t
             ${{ else }}:
@@ -164,6 +175,7 @@ jobs:
           Configuration: Debug
           _HostPython: python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+          TailcallingOption: ''
           Artifact: bin_arm64_td
 
   steps:
@@ -186,7 +198,8 @@ jobs:
           Platform: x64
           _HostPython: .\python
           PythonExePattern: python.exe
-          ExtraOptions: ${{ parameters.ExtraOptions }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
+          ExtraOptions: ${{ parameters.ExtraOptions }}
+          TailcallingOption: ${{ parameters.TailcallingOption }}
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -198,7 +211,8 @@ jobs:
             Platform: x64
             _HostPython: .\python
             PythonExePattern: python3*t.exe
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}${{ if eq(parameters.DoTailcalling, 'true') }} ' --tail-call-interp'
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
+            TailcallingOption: ${{ parameters.TailcallingOption }}
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:

From 6aa18d505ed2f2bfade3c82c89d703c0d7e47c9f Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 26 Feb 2026 22:11:55 +0100
Subject: [PATCH 4/8] Update windows-release/azure-pipelines.yml

Co-authored-by: Steve Dower <steve.dower@microsoft.com>
---
 windows-release/azure-pipelines.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/windows-release/azure-pipelines.yml b/windows-release/azure-pipelines.yml
index b58a2b8a..f72ce9e8 100644
--- a/windows-release/azure-pipelines.yml
+++ b/windows-release/azure-pipelines.yml
@@ -165,7 +165,7 @@ stages:
   - stage: Build
     displayName: Build binaries
     pool:
-      vmImage: ${{ if(eq(parameters.DoTailcalling, 'true'), 'windows-2025-vs2026', parameters.vmImage) }}
+      vmImage: ${{ iif(eq(parameters.DoTailcalling, 'true'), 'windows-2025-vs2026', parameters.vmImage) }}
     jobs:
     - template: start-arm64vm.yml
       parameters:

From 33a030b9f8f25301c26b11d334a3e0cd5f32f3f2 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 26 Feb 2026 22:12:10 +0100
Subject: [PATCH 5/8] Update windows-release/stage-build.yml

Co-authored-by: Steve Dower <steve.dower@microsoft.com>
---
 windows-release/stage-build.yml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/windows-release/stage-build.yml b/windows-release/stage-build.yml
index 82fa5368..6e97052f 100644
--- a/windows-release/stage-build.yml
+++ b/windows-release/stage-build.yml
@@ -74,8 +74,7 @@ jobs:
           Platform: x64
           Configuration: Release
           _HostPython: .\python
-          ExtraOptions: ${{ parameters.ExtraOptions }}
-          TailcallingOption: ${{ parameters.TailcallingOption }}
+          ExtraOptions: ${{ parameters.ExtraOptions }} ${{ parameters.TailcallingOption }}
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:

From 6db61cb63682801471b35eb2ed4226f2343f1637 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 26 Feb 2026 22:36:24 +0100
Subject: [PATCH 6/8] $(TailcallingOption) not needed anymore

add missing ${{ parameters.TailcallingOption }}

remove unneeded TailcallingOption: ''
---
 windows-release/build-steps-pgo.yml |  4 ++--
 windows-release/build-steps.yml     |  4 ++--
 windows-release/stage-build.yml     | 19 +++----------------
 3 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/windows-release/build-steps-pgo.yml b/windows-release/build-steps-pgo.yml
index 2195285a..f55ec42c 100644
--- a/windows-release/build-steps-pgo.yml
+++ b/windows-release/build-steps-pgo.yml
@@ -22,7 +22,7 @@ steps:
 - ${{ if eq(parameters.PGInstrument, 'true') }}:
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) -c PGInstrument $(ExtraOptions) $(TailcallingOption)
+      .\PCbuild\build.bat -v -p $(Platform) -c PGInstrument $(ExtraOptions)
     displayName: 'Run build'
     env:
       IncludeUwp: true
@@ -100,7 +100,7 @@ steps:
 
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) -c PGUpdate $(ExtraOptions) $(TailcallingOption)
+      .\PCbuild\build.bat -v -p $(Platform) -c PGUpdate $(ExtraOptions)
     displayName: 'Run build with PGO'
     env:
       IncludeUwp: true
diff --git a/windows-release/build-steps.yml b/windows-release/build-steps.yml
index a62f3a22..300d7e79 100644
--- a/windows-release/build-steps.yml
+++ b/windows-release/build-steps.yml
@@ -18,7 +18,7 @@ steps:
 - ${{ if eq(parameters.ShouldPGO, 'false') }}:
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) -c $(Configuration) $(ExtraOptions) $(TailcallingOption)
+      .\PCbuild\build.bat -v -p $(Platform) -c $(Configuration) $(ExtraOptions)
     displayName: 'Run build'
     env:
       IncludeUwp: true
@@ -27,7 +27,7 @@ steps:
 - ${{ else }}:
   - powershell: |
       $env:SigningCertificate = $null
-      .\PCbuild\build.bat -v -p $(Platform) --pgo $(ExtraOptions) $(TailcallingOption)
+      .\PCbuild\build.bat -v -p $(Platform) --pgo $(ExtraOptions)
     displayName: 'Run build with PGO'
     env:
       IncludeUwp: true
diff --git a/windows-release/stage-build.yml b/windows-release/stage-build.yml
index 6e97052f..97f85d8d 100644
--- a/windows-release/stage-build.yml
+++ b/windows-release/stage-build.yml
@@ -53,7 +53,6 @@ jobs:
         Configuration: Release
         _HostPython: .\python
         ExtraOptions: ${{ parameters.ExtraOptions }}
-        TailcallingOption: ''
         ${{ if eq(parameters.ToBeSigned, 'true') }}:
           Artifact: unsigned_win32
         ${{ else }}:
@@ -65,7 +64,6 @@ jobs:
         Configuration: Debug
         _HostPython: .\python
         ExtraOptions: ${{ parameters.ExtraOptions }}
-        TailcallingOption: ''
         Artifact: bin_win32_d
       ${{ if ne(parameters.DoPGO, 'true') }}:
         amd64:
@@ -86,7 +84,6 @@ jobs:
         Configuration: Debug
         _HostPython: .\python
         ExtraOptions: ${{ parameters.ExtraOptions }}
-        TailcallingOption: ''
         Artifact: bin_amd64_d
       ${{ if or(ne(parameters.DoPGO, 'true'), ne(parameters.DoPGOARM64, 'true')) }}:
         arm64:
@@ -96,7 +93,6 @@ jobs:
           Configuration: Release
           _HostPython: python
           ExtraOptions: ${{ parameters.ExtraOptions }}
-          TailcallingOption: ''
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_arm64
           ${{ else }}:
@@ -108,7 +104,6 @@ jobs:
         Configuration: Debug
         _HostPython: python
         ExtraOptions: ${{ parameters.ExtraOptions }}
-        TailcallingOption: ''
         Artifact: bin_arm64_d
       ${{ if eq(parameters.DoFreethreaded, 'true') }}:
         win32_t:
@@ -118,7 +113,6 @@ jobs:
           Configuration: Release
           _HostPython: .\python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-          TailcallingOption: ''
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_win32_t
           ${{ else }}:
@@ -130,7 +124,6 @@ jobs:
           Configuration: Debug
           _HostPython: .\python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-          TailcallingOption: ''
           Artifact: bin_win32_td
         ${{ if ne(parameters.DoPGO, 'true') }}:
           amd64_t:
@@ -139,8 +132,7 @@ jobs:
             Platform: x64
             Configuration: Release
             _HostPython: .\python
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-            TailcallingOption: ${{ parameters.TailcallingOption }}
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }} ${{ parameters.TailcallingOption }}
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:
@@ -152,7 +144,6 @@ jobs:
           Configuration: Debug
           _HostPython: .\python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-          TailcallingOption: ''
           Artifact: bin_amd64_td
         ${{ if or(ne(parameters.DoPGO, 'true'), ne(parameters.DoPGOARM64, 'true')) }}:
           arm64_t:
@@ -162,7 +153,6 @@ jobs:
             Configuration: Release
             _HostPython: python
             ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-            TailcallingOption: ''
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_arm64_t
             ${{ else }}:
@@ -174,7 +164,6 @@ jobs:
           Configuration: Debug
           _HostPython: python
           ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-          TailcallingOption: ''
           Artifact: bin_arm64_td
 
   steps:
@@ -197,8 +186,7 @@ jobs:
           Platform: x64
           _HostPython: .\python
           PythonExePattern: python.exe
-          ExtraOptions: ${{ parameters.ExtraOptions }}
-          TailcallingOption: ${{ parameters.TailcallingOption }}
+          ExtraOptions: ${{ parameters.ExtraOptions }} ${{ parameters.TailcallingOption }}
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -210,8 +198,7 @@ jobs:
             Platform: x64
             _HostPython: .\python
             PythonExePattern: python3*t.exe
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }}
-            TailcallingOption: ${{ parameters.TailcallingOption }}
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }} ${{ parameters.TailcallingOption }}
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:

From 873ebb7d9fe9b339ba8d0f862df7114aba08ae34 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Fri, 27 Feb 2026 11:50:32 +0100
Subject: [PATCH 7/8] Update windows-release/azure-pipelines.yml

Co-authored-by: Steve Dower <steve.dower@microsoft.com>
---
 windows-release/azure-pipelines.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/windows-release/azure-pipelines.yml b/windows-release/azure-pipelines.yml
index f72ce9e8..04a1fa81 100644
--- a/windows-release/azure-pipelines.yml
+++ b/windows-release/azure-pipelines.yml
@@ -43,7 +43,7 @@ parameters:
   type: string
   default: '(default)'
 - name: DoTailcalling
-  displayName: "Build AMD64 with tailcalling support (3.15 and later)"
+  displayName: "Build with tail-calling support (3.15 and later)"
   type: boolean
   default: false
 - name: DoJIT

From 0f5d98a953187f00553d45217783be1d2f9e2d13 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Fri, 27 Feb 2026 12:26:28 +0100
Subject: [PATCH 8/8] Tailcalling -> TailCalling

---
 windows-release/azure-pipelines.yml | 10 +++++-----
 windows-release/stage-build.yml     | 10 +++++-----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/windows-release/azure-pipelines.yml b/windows-release/azure-pipelines.yml
index 04a1fa81..f4e08765 100644
--- a/windows-release/azure-pipelines.yml
+++ b/windows-release/azure-pipelines.yml
@@ -42,7 +42,7 @@ parameters:
   displayName: "Signature description"
   type: string
   default: '(default)'
-- name: DoTailcalling
+- name: DoTailCalling
   displayName: "Build with tail-calling support (3.15 and later)"
   type: boolean
   default: false
@@ -165,7 +165,7 @@ stages:
   - stage: Build
     displayName: Build binaries
     pool:
-      vmImage: ${{ iif(eq(parameters.DoTailcalling, 'true'), 'windows-2025-vs2026', parameters.vmImage) }}
+      vmImage: ${{ iif(eq(parameters.DoTailCalling, 'true'), 'windows-2025-vs2026', parameters.vmImage) }}
     jobs:
     - template: start-arm64vm.yml
       parameters:
@@ -190,10 +190,10 @@ stages:
           ExtraOptionsFreethreaded: '--disable-gil --experimental-jit-off'
         ${{ else }}:
           ExtraOptionsFreethreaded: '--disable-gil --experimental-jit'
-        ${{ if ne(parameters.DoTailcalling, 'true') }}:
-          TailcallingOption: ''
+        ${{ if ne(parameters.DoTailCalling, 'true') }}:
+          TailCallingOption: ''
         ${{ else }}:
-          TailcallingOption: '--tail-call-interp'
+          TailCallingOption: '--tail-call-interp'
   - stage: Sign
     displayName: Sign binaries
     dependsOn: Build
diff --git a/windows-release/stage-build.yml b/windows-release/stage-build.yml
index 97f85d8d..12d8076e 100644
--- a/windows-release/stage-build.yml
+++ b/windows-release/stage-build.yml
@@ -6,7 +6,7 @@ parameters:
   ToBeSigned: false
   ExtraOptions: ''
   ExtraOptionsFreethreaded: '--disable-gil'
-  TailcallingOption: ''
+  TailCallingOption: ''
 
 jobs:
 - job: Build_Docs
@@ -72,7 +72,7 @@ jobs:
           Platform: x64
           Configuration: Release
           _HostPython: .\python
-          ExtraOptions: ${{ parameters.ExtraOptions }} ${{ parameters.TailcallingOption }}
+          ExtraOptions: ${{ parameters.ExtraOptions }} ${{ parameters.TailCallingOption }}
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -132,7 +132,7 @@ jobs:
             Platform: x64
             Configuration: Release
             _HostPython: .\python
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }} ${{ parameters.TailcallingOption }}
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }} ${{ parameters.TailCallingOption }}
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}:
@@ -186,7 +186,7 @@ jobs:
           Platform: x64
           _HostPython: .\python
           PythonExePattern: python.exe
-          ExtraOptions: ${{ parameters.ExtraOptions }} ${{ parameters.TailcallingOption }}
+          ExtraOptions: ${{ parameters.ExtraOptions }} ${{ parameters.TailCallingOption }}
           ${{ if eq(parameters.ToBeSigned, 'true') }}:
             Artifact: unsigned_amd64
           ${{ else }}:
@@ -198,7 +198,7 @@ jobs:
             Platform: x64
             _HostPython: .\python
             PythonExePattern: python3*t.exe
-            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }} ${{ parameters.TailcallingOption }}
+            ExtraOptions: ${{ parameters.ExtraOptionsFreethreaded }} ${{ parameters.TailCallingOption }}
             ${{ if eq(parameters.ToBeSigned, 'true') }}:
               Artifact: unsigned_amd64_t
             ${{ else }}: