Conditionally set SYSTEM PATH in host install (#118092)

* Conditionally set SYSTEM PATH in host install

* Address ICE18 error

Author: joeloff

src/installer/pkg/sfx/installers/dotnet-host.proj

@@ -12,7 +12,11 @@
     <!-- Contributes to DependencyKey which ensures stable provider key - do not change -->
     <WixDependencyKeyName>Dotnet_CLI_SharedHost</WixDependencyKeyName>
     <OutputFilesCandleVariable>HostSrc</OutputFilesCandleVariable>
-    <MajorUpgradeSchedule>afterInstallExecute</MajorUpgradeSchedule>
+
+    <!-- Scheduling RemoveExistingProducts after InstallInitialize will remove the previous install first
+         before installing the new version. This allows compositional changes in major upgrades
+         and supports rollback, provided it is not turned off using machine policies (DisableRollback is not set to 1). -->
+    <MajorUpgradeSchedule>afterInstallInitialize</MajorUpgradeSchedule>
     <VersionInstallerName>false</VersionInstallerName>
     <UseBrandingNameInLinuxPackageDescription>true</UseBrandingNameInLinuxPackageDescription>
     <MacOSComponentNamePackType>sharedhost</MacOSComponentNamePackType>
@@ -26,7 +30,7 @@
   <ItemGroup>
     <WixSrcFile Include="host.wxs" />
     <WixExtraComponentGroupRefId Include="InstallSharedHostandDetectionKeys" />
-    <CandleVariables Include="ExtraPropertyRefIds" Value="ProductCPU;RTM_ProductVersion" />
+    <CandleVariables Include="ExtraPropertyRefIds" Value="ProductCPU;RTM_ProductVersion;DISABLE_SETTING_HOST_PATH" />
     <!-- Enables stable provider key - do not change -->
     <CandleVariables Include="DependencyKey" Value="$(WixDependencyKeyName)_$(MajorVersion).$(MinorVersion)_$(TargetArchitecture)" />
   </ItemGroup>

src/installer/pkg/sfx/installers/host.wxs

@@ -38,20 +38,19 @@
         </RegistryKey>
       </Component>
 
-      <Component Id="cmdPath" Directory="DOTNETHOME" Guid="*">
+      <Component Id="cmpPath" Directory="DOTNETHOME" Guid="*">
         <?if $(var.Platform)~=x64 ?>
-        <!-- For x64 installer, only add to PATH when actually on native architecture -->
+        <!-- For x64 installer, only add the sharedhost key when actually on native architecture. -->
         <Condition>NOT NON_NATIVE_ARCHITECTURE</Condition>
         <?elseif $(var.Platform)~=x86 ?>
-        <!-- For x86 installer, only add to PATH when not on 64-bit platform -->
+        <!-- For x86 installer, only add the key when not on 64-bit platform. -->
         <Condition>NOT VersionNT64</Condition>
         <?endif?>
 
         <!-- A stable keypath with the right SxS characteristics for our PATH entry-->
         <RegistryKey Root="HKLM" Key="SOFTWARE\dotnet\Setup\InstalledVersions\$(var.Platform)\sharedhost">
           <RegistryValue KeyPath="yes" Action="write" Name="Path" Type="string" Value="[DOTNETHOME]"/>
         </RegistryKey>
-        <Environment Id="E_PATH" Name="PATH" Value="[DOTNETHOME]" Part="last" Action="set" System="yes" />
       </Component>
 
       <Component Id="cmpLicenseFiles" Directory="DOTNETHOME" Guid="{A61CBE5B-1282-4F29-90AD-63597AA2372E}">
@@ -63,6 +62,7 @@
         </File>
       </Component>
 
+      <ComponentRef Id="cmpSetPath" />
     </ComponentGroup>
 
     <Property Id="ProductCPU" Value="$(var.Platform)" />
@@ -76,6 +76,32 @@
     <CustomActionRef Id="Set_PROGRAMFILES_DOTNET_NON_NATIVE_ARCHITECTURE" />
     <?endif?>
   </Fragment>
+
+  <Fragment>
+    <Property Id="DISABLE_SETTING_HOST_PATH" Secure="yes">
+      <RegistrySearch Id="DisableSettingHostPathSearch" Root="HKLM" Key="SOFTWARE\Microsoft\.NET" Type="raw" Name="DisableSettingHostPath"/>
+    </Property>
+
+    <Component Id="cmpSetPath" Guid="{0B910ED8-0877-473D-8658-647382324433}" Directory="DOTNETHOME">
+      <CreateFolder />
+      <!-- Always set the SYSTEM PATH, unless DisableSettingHostPath is 1. -->
+      <?if $(var.Platform)~=x64 ?>
+      <!-- For x64 installer, only add to PATH when actually on native architecture. -->
+      <Condition><![CDATA[DISABLE_SETTING_HOST_PATH <> "#1" AND NOT NON_NATIVE_ARCHITECTURE]]></Condition>
+      <?elseif $(var.Platform)~=x86 ?>
+      <!-- For x86 installer, only add to PATH when not on 64-bit platform. -->
+      <Condition><![CDATA[DISABLE_SETTING_HOST_PATH <> "#1" AND NOT VersionNT64]]></Condition>
+      <?endif?>
+      <Environment Id="E_PATH" Name="PATH" Value="[DOTNETHOME]" Part="last" Action="set" System="yes" />
+    </Component>
+
+    <InstallExecuteSequence>
+      <!-- Only broadcast the change if the component is enabled. -->
+      <Custom Action="WixBroadcastEnvironmentChange" After="InstallFinalize">
+        <![CDATA[DISABLE_SETTING_HOST_PATH <> "#1"]]>
+      </Custom>
+    </InstallExecuteSequence>
+  </Fragment>
 
   <Fragment>
     <!-- Unlike DOTNETHOME which gives precedence to a user specified value over an x64 suffix, here we always want the suffixed path -->