new trimmer feature System.TimeZoneInfo.Invariant

docs/design/features/timezone-invariant-mode.md

@@ -8,9 +8,28 @@ Therefore dotnet bundles the timezone database as binary as part of the runtime.
 That makes download size larger and application startup slower.
 If your application doesn't need to work with time zone information, you could use this feature to make the runtime about 200KB smaller.
 
-You enable it in project file:
+## Enabling the invariant mode
+
+Applications can enable the invariant mode by either of the following:
+
+1. in project file:
+
     ```xml
     <PropertyGroup>
         <InvariantTimezone>true</InvariantTimezone>
     </PropertyGroup>
     ```
+
+2. in `runtimeconfig.json` file:
+
+    ```json
+    {
+        "runtimeOptions": {
+            "configProperties": {
+                "System.TimeZoneInfo.Invariant": true
+            }
+        }
+    }
+    ```
+
+3. setting environment variable value `DOTNET_SYSTEM_TIMEZONE_INVARIANT` to `true` or `1`.

src/coreclr/tools/aot/ILCompiler.Trimming.Tests/TestCasesRunner/TrimmingArgumentBuilder.cs

@@ -48,6 +48,7 @@ public TrimmingArgumentBuilder (TestCaseMetadataProvider metadataProvider)
 			Options.FeatureSwitches.Add ("System.Text.Encoding.EnableUnsafeUTF7Encoding", false);
 			Options.FeatureSwitches.Add ("System.Diagnostics.Tracing.EventSource.IsSupported", false);
 			Options.FeatureSwitches.Add ("System.Globalization.Invariant", true);
+			Options.FeatureSwitches.Add ("System.TimeZoneInfo.Invariant", true);
 			Options.FeatureSwitches.Add ("System.Resources.UseSystemResourceKeys", true);
 
 			Options.FrameworkCompilation = false;

src/coreclr/tools/aot/ILCompiler/repro/repro.csproj

@@ -40,6 +40,7 @@
       <ReproResponseLines Include="--feature:System.Linq.Expressions.CanEmitObjectArrayDelegate=false" />
       <ReproResponseLines Include="--feature:System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeSupported=false" />
       <ReproResponseLines Include="--feature:System.Globalization.Invariant=true" />
+      <ReproResponseLines Include="--feature:System.TimeZoneInfo.Invariant=true" />
       <ReproResponseLines Include="--feature:System.Diagnostics.Debugger.IsSupported=false" />
       <ReproResponseLines Include="--feature:System.StartupHookProvider.IsSupported=false" />
     </ItemGroup>

src/installer/pkg/sfx/Microsoft.NETCore.App/Directory.Build.props

@@ -253,7 +253,6 @@
     <PlatformManifestFileEntry Include="wasi-link.rsp" IsNative="true" />
     <PlatformManifestFileEntry Include="ILLink.Substitutions.WasmIntrinsics.xml" IsNative="true" />
     <PlatformManifestFileEntry Include="ILLink.Substitutions.NoWasmIntrinsics.xml" IsNative="true" />
-    <PlatformManifestFileEntry Include="ILLink.Substitutions.LegacyJsInterop.xml" IsNative="true" />
     <!-- wasi specific -->
     <PlatformManifestFileEntry Include="main.c" IsNative="true" />
     <PlatformManifestFileEntry Include="driver.h" IsNative="true" />

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Substitutions.Shared.xml

@@ -16,6 +16,9 @@
     <type fullname="System.Globalization.GlobalizationMode/Settings">
       <method signature="System.Boolean get_Invariant()" body="stub" value="false" feature="System.Globalization.Invariant" featurevalue="false" />
     </type>
+    <type fullname="System.TimeZoneInfo">
+      <method signature="System.Boolean get_Invariant()" body="stub" value="true" feature="System.TimeZoneInfo.Invariant" featurevalue="true" />
+    </type>
     <type fullname="System.Resources.ResourceReader">
       <method signature="System.Boolean InitializeBinaryFormatter()" body="stub" value="false" feature="System.Runtime.Serialization.EnableUnsafeBinaryFormatterSerialization" featurevalue="false" />
     </type>

src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.NonAndroid.cs

@@ -147,6 +147,11 @@ private static TimeZoneInfoResult TryGetTimeZoneFromLocalMachineCore(string id,
         /// </remarks>
         private static IEnumerable<string> GetTimeZoneIds()
         {
+            if (Invariant)
+            {
+                return Array.Empty<string>();
+            }
+
             try
             {
                 var fileName = Path.Combine(GetTimeZoneDirectory(), TimeZoneFileName);
@@ -469,6 +474,11 @@ private static bool TryLoadTzFile(string tzFilePath, [NotNullWhen(true)] ref byt
 #if TARGET_WASI || TARGET_BROWSER
         private static bool TryLoadEmbeddedTzFile(string name, [NotNullWhen(true)] out byte[]? rawData)
         {
+            if (Invariant)
+            {
+                rawData = null;
+                return false;
+            }
             IntPtr bytes = Interop.Sys.GetTimeZoneData(name, out int length);
             if (bytes == IntPtr.Zero)
             {
@@ -504,6 +514,10 @@ private static bool TryGetLocalTzFile([NotNullWhen(true)] out byte[]? rawData, [
         {
             rawData = null;
             id = null;
+            if (Invariant)
+            {
+                return false;
+            }
             string? tzVariable = GetTzEnvironmentVariable();
 
             // If the env var is null, on iOS/tvOS, grab the default tz from the device.
@@ -573,6 +587,11 @@ private static bool TryGetLocalTzFile([NotNullWhen(true)] out byte[]? rawData, [
         /// </summary>
         private static TimeZoneInfo GetLocalTimeZoneFromTzFile()
         {
+            if (Invariant)
+            {
+                return Utc;
+            }
+
             byte[]? rawData;
             string? id;
             if (TryGetLocalTzFile(out rawData, out id))

src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.cs

@@ -60,6 +60,8 @@ private enum TimeZoneInfoResult
         private static readonly TimeZoneInfo s_utcTimeZone = CreateUtcTimeZone();
         private static CachedData s_cachedData = new CachedData();
 
+        internal static bool Invariant { get; } = AppContextConfigHelper.GetBooleanConfig("System.TimeZoneInfo.Invariant", "DOTNET_SYSTEM_TIMEZONE_INVARIANT");
+
         //
         // All cached data are encapsulated in a helper class to allow consistent view even when the data are refreshed using ClearCachedData()
         //

src/mono/browser/runtime/driver.c

@@ -222,7 +222,9 @@ mono_wasm_load_runtime (int debug_level)
 	monovm_initialize (2, appctx_keys, appctx_values);
 
 #ifndef INVARIANT_TIMEZONE
-	mono_register_timezones_bundle ();
+	char* invariant_timezone = monoeg_g_getenv ("DOTNET_SYSTEM_TIMEZONE_INVARIANT");
+	if (strcmp(invariant_timezone, "true") != 0 && strcmp(invariant_timezone, "1") != 0)
+		mono_register_timezones_bundle ();
 #endif /* INVARIANT_TIMEZONE */
 
 	root_domain = mono_wasm_load_runtime_common (debug_level, wasm_trace_logger, interp_opts);

src/mono/wasi/runtime/driver.c

@@ -266,7 +266,9 @@ mono_wasm_load_runtime (int debug_level)
 	monovm_initialize (2, appctx_keys, appctx_values);
 
 #ifndef INVARIANT_TIMEZONE
-	mono_register_timezones_bundle ();
+	char* invariant_timezone = monoeg_g_getenv ("DOTNET_SYSTEM_TIMEZONE_INVARIANT");
+	if (strcmp(invariant_timezone, "true") != 0 && strcmp(invariant_timezone, "1") != 0)
+		mono_register_timezones_bundle ();
 #endif /* INVARIANT_TIMEZONE */
 #ifdef WASM_SINGLE_FILE
 	mono_register_assemblies_bundle ();