Switch from IsRidAgnostic metadata to AcceptsRuntimeIdentifier property

Also always treat SelfContained the same as RuntimeIdentifier as far as whether the properties should be allowed to flow across project references

src/Tasks/Microsoft.Common.CrossTargeting.targets

@@ -43,9 +43,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         <TargetPlatformMonikers>@(_TargetFrameworkInfo->'%(TargetPlatformMonikers)')</TargetPlatformMonikers>
         <AdditionalPropertiesFromProject>$(_AdditionalPropertiesFromProject)</AdditionalPropertiesFromProject>
         <HasSingleTargetFramework>false</HasSingleTargetFramework>
-        <!-- indicate to caller that project is RID agnostic so that a global property RuntimeIdentifier value can be removed -->
-        <IsRidAgnostic>false</IsRidAgnostic>
-        <IsRidAgnostic Condition=" '$(RuntimeIdentifier)' == '' and '$(RuntimeIdentifiers)' == '' ">true</IsRidAgnostic>
+        <AcceptsRuntimeIdentifier>@(_TargetFrameworkInfo->'%(AcceptsRuntimeIdentifier)')</AcceptsRuntimeIdentifier>
         <!-- Extract necessary information for SetPlatform negotiation -->
         <!-- This target does not run for cpp projects. -->
         <IsVcxOrNativeProj>false</IsVcxOrNativeProj>

src/Tasks/Microsoft.Common.CurrentVersion.targets

@@ -1844,17 +1844,12 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         <UndefineProperties>%(AnnotatedProjects.UndefineProperties);TargetFramework</UndefineProperties>
       </AnnotatedProjects>
 
-      <!-- If the project is RID agnostic, undefine the RuntimeIdentifier property to avoid another evaluation. -->
-      <AnnotatedProjects Condition="'@(AnnotatedProjects)' == '%(Identity)' and '%(AnnotatedProjects.IsRidAgnostic)' == 'true'">
-        <UndefineProperties>%(AnnotatedProjects.UndefineProperties);RuntimeIdentifier</UndefineProperties>
-
-        <!-- Also undefine SelfContained property if it was defined on the command line.  Otherwise a command such as
-             "dotnet build -r win-x64 -/-self-contained" would fail to build referenced projects, as they would have
-             SelfContained defined but no RuntimeIdentifier.
-             We only undefine this if the specific command-line option was used, in order to avoid breaking projects
-             that were passing /p:SelfContained=true on the command-line and relying on it flowing acress projects
-             (they were then setting the RuntimeIdentifier if SelfContained was true in their props files) -->
-        <UndefineProperties Condition="'$(_CommandLineDefinedSelfContained)' == 'true'">%(AnnotatedProjects.UndefineProperties);SelfContained</UndefineProperties>
+      <!-- Add RuntimeIdentifier and SelfContained to the list of global properties that should not flow to the referenced project,
+           unless the project is expecting those properties to flow.
+           We include SelfContained together with RuntimeIdentifier, because otherwise a referenced project could try to build with
+           SelfContained set to true but no RuntimeIdentifier set, which causes an error (for Exe projects). -->
+      <AnnotatedProjects Condition="'@(AnnotatedProjects)' == '%(Identity)' and '%(AnnotatedProjects.AcceptsRuntimeIdentifier)' != 'true'">
+        <UndefineProperties>%(AnnotatedProjects.UndefineProperties);RuntimeIdentifier;SelfContained</UndefineProperties>
       </AnnotatedProjects>
 
       <!--
@@ -1887,9 +1882,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         <TargetPlatformMonikers>@(_TargetFrameworkInfo->'%(TargetPlatformMonikers)')</TargetPlatformMonikers>
         <AdditionalPropertiesFromProject>$(_AdditionalPropertiesFromProject)</AdditionalPropertiesFromProject>
         <HasSingleTargetFramework>true</HasSingleTargetFramework>
-        <!-- indicate to caller that project is RID agnostic so that a global property RuntimeIdentifier value can be removed -->
-        <IsRidAgnostic>false</IsRidAgnostic>
-        <IsRidAgnostic Condition=" '$(RuntimeIdentifier)' == '' and '$(RuntimeIdentifiers)' == '' ">true</IsRidAgnostic>
+        <AcceptsRuntimeIdentifier>@(_TargetFrameworkInfo->'%(AcceptsRuntimeIdentifier)')</AcceptsRuntimeIdentifier>
         <!-- Extract necessary information for SetPlatform negotiation -->
         <IsVcxOrNativeProj Condition="'$(MSBuildProjectExtension)' == '.vcxproj' or '$(MSBuildProjectExtension)' == '.nativeproj'">true</IsVcxOrNativeProj>
         <Platforms>$(Platforms)</Platforms>
@@ -1929,6 +1922,17 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         <TargetPlatformMonikers>$(TargetPlatformMoniker)</TargetPlatformMonikers>
         <TargetPlatformMonikers Condition="'$(TargetPlatformMoniker)' == ''">None</TargetPlatformMonikers>
         <AdditionalPropertiesFromProject>$(_AdditionalTargetFrameworkInfoProperties)</AdditionalPropertiesFromProject>
+
+        <!-- Determine whether a global RuntimeIdentifier property should flow to this project across project references.
+             We will let the property flow if any of the following are true:
+             - The AcceptsRuntimeIdentifier property is set to true (or really, any non-empty value except "false")
+             - The RuntimeIdentifier is set
+             - The RuntimeIdentifiers property is set
+             Otherwise, we will include RuntimeIdentifier (and SelfContained) in the list of global properties to remove across project references-->
+        <AcceptsRuntimeIdentifier>$(AcceptsRuntimeIdentifier)</AcceptsRuntimeIdentifier>
+        <AcceptsRuntimeIdentifier Condition=" '$(AcceptsRuntimeIdentifier)' == ''">true</AcceptsRuntimeIdentifier>
+        <AcceptsRuntimeIdentifier Condition=" '$(AcceptsRuntimeIdentifier)' == '' and '$(RuntimeIdentifier)' == '' and '$(RuntimeIdentifiers)' == '' ">false</AcceptsRuntimeIdentifier>
+
       </_TargetFrameworkInfo>
     </ItemGroup>