From c09ac2fafdd438e94f19f25a59bb473819b8a3e3 Mon Sep 17 00:00:00 2001
From: Omair Majid <omajid@redhat.com>
Date: Tue, 2 Jun 2026 16:42:35 -0400
Subject: [PATCH 1/2] Use deterministic values for _BuildNumber

Use `DeterministicTimestamp` and `SOURCE_BUILD_EPOCH` to set a
deterministic date for `_BuildNumber` instead of the wall-clock-time
(`DateTime.Now`).

`DeterministicTimetsamp` is defined and documented in this NuGet spec:
https://github.com/NuGet/Home/blob/dev/accepted/2026/deterministic-pack-revisited.md

`SOURCE_DATE_EPOCH` is defined and documented in
https://reproducible-builds.org/specs/source-date-epoch/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .../tools/Version.BeforeCommonTargets.targets            | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets b/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets
index 697e4189673..b5a179f3e56 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets
@@ -24,6 +24,10 @@
     <IsShippingVsix Condition="'$(IsShippingVsix)' == ''">$(IsShipping)</IsShippingVsix>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <DeterministicTimestamp Condition="'$(DeterministicTimestamp)' == '' and '$(SOURCE_DATE_EPOCH)' != ''">$(SOURCE_DATE_EPOCH)</DeterministicTimestamp>
+  </PropertyGroup>
+
   <!--
     Specification: https://github.com/dotnet/arcade/blob/master/Documentation/CorePackages/Versioning.md
 
@@ -44,7 +48,10 @@
       and should only be enabled when it's necessary to test-install the MSIs produced by the build.
     -->
     <_BuildNumber>$(OfficialBuildId)</_BuildNumber>
-    <_BuildNumber Condition="'$(OfficialBuildId)' == ''">$([System.DateTime]::Now.ToString(yyyyMMdd)).1</_BuildNumber>
+    <!-- Use DeterministicTimestamp before falling back to wall-clock -->
+    <_BuildNumber Condition="'$(_BuildNumber)' == '' and '$(DeterministicTimestamp)' != '' and '$(DeterministicTimestamp)' != 'true' and '$(DeterministicTimestamp)' != 'false' and !$(DeterministicTimestamp.Contains('-'))">$([System.DateTimeOffset]::FromUnixTimeSeconds($(DeterministicTimestamp)).UtcDateTime.ToString(yyyyMMdd)).1</_BuildNumber>
+    <_BuildNumber Condition="'$(_BuildNumber)' == '' and $(DeterministicTimestamp.Contains('-'))">$([System.DateTimeOffset]::Parse($(DeterministicTimestamp)).UtcDateTime.ToString(yyyyMMdd)).1</_BuildNumber>
+    <_BuildNumber Condition="'$(_BuildNumber)' == ''">$([System.DateTime]::Now.ToString(yyyyMMdd)).1</_BuildNumber>
 
     <!--
       OfficialBuildId is assumed to have format "20yymmdd.r" (the assumption is checked later in a target).

From 3fb9055d531cae2eb07ef944737d6a9df15a1f27 Mon Sep 17 00:00:00 2001
From: Omair Majid <omajid@redhat.com>
Date: Thu, 4 Jun 2026 11:15:12 -0400
Subject: [PATCH 2/2] Use DateTime.UtcNow instead of Now for _BuildNumber

---
 .../tools/Version.BeforeCommonTargets.targets                   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets b/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets
index b5a179f3e56..873b7bde22e 100644
--- a/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets
+++ b/src/Microsoft.DotNet.Arcade.Sdk/tools/Version.BeforeCommonTargets.targets
@@ -51,7 +51,7 @@
     <!-- Use DeterministicTimestamp before falling back to wall-clock -->
     <_BuildNumber Condition="'$(_BuildNumber)' == '' and '$(DeterministicTimestamp)' != '' and '$(DeterministicTimestamp)' != 'true' and '$(DeterministicTimestamp)' != 'false' and !$(DeterministicTimestamp.Contains('-'))">$([System.DateTimeOffset]::FromUnixTimeSeconds($(DeterministicTimestamp)).UtcDateTime.ToString(yyyyMMdd)).1</_BuildNumber>
     <_BuildNumber Condition="'$(_BuildNumber)' == '' and $(DeterministicTimestamp.Contains('-'))">$([System.DateTimeOffset]::Parse($(DeterministicTimestamp)).UtcDateTime.ToString(yyyyMMdd)).1</_BuildNumber>
-    <_BuildNumber Condition="'$(_BuildNumber)' == ''">$([System.DateTime]::Now.ToString(yyyyMMdd)).1</_BuildNumber>
+    <_BuildNumber Condition="'$(_BuildNumber)' == ''">$([System.DateTime]::UtcNow.ToString(yyyyMMdd)).1</_BuildNumber>
 
     <!--
       OfficialBuildId is assumed to have format "20yymmdd.r" (the assumption is checked later in a target).