loc: replace reflection-based args with tuple-params + IDictionary overloads by codemonkeychris · Pull Request #354 · microsoft/microsoft-ui-reactor

codemonkeychris · 2026-05-20T15:39:43Z

Why

PR #353 skipped Localization_LocaleSwitching under AOT because
t.Message(key, new { name = "World" }) reflects over the anonymous type
to build the ICU args dictionary, and the trimmer drops the property
getters under NativeAOT (ctor + backing fields are statically reachable
from the new { ... } site, but property getters aren't, since the only
reader was a reflective GetProperties() call). GetProperties()
returned empty, MessageFormat.FormatMessage threw on {name}, the
catch swallowed, and the raw ICU pattern leaked through to the UI.

We don't want a reflection-based dispatcher in this code path anyway —
it forces every [UnconditionalSuppressMessage] we''ve written on the
type, and the security model (refuse arbitrary DTOs via
IsAcceptableArgsContainer) is doing nothing the type system couldn''t
do statically.

What

Replace the object?-typed args parameter with two AOT-safe overloads:

// 1. Explicit dict — for shared/programmatic args
public string Message(MessageKey key, IDictionary<string, object>? args = null);

// 2. Tuple-params — for the compact inline case
public string Message(MessageKey key,
    (string Name, object Value) arg1,
    params (string Name, object Value)[] more);

Callers go from this:

t.Message(Greeting, new { name = "World" })
t.Message(SearchResults, new { count = 0, query = "test" })

to this:

t.Message(Greeting, ("name", "World"))
t.Message(SearchResults, ("count", 0), ("query", "test"))

Same shape for RichMessage. The tagged variant uses the dict overload
because params must be last:

t.RichMessage(Loc.Profile.Welcome,
    args: new Dictionary<string, object> { ["name"] = "Alice" },
    tags: new() { ["bold"] = text => Text(text).Bold() })

ValueTuple is a nominal type with concrete fields — building a
Dictionary<string,object> from tuple values needs zero reflection,
so the whole IL2026/IL2070 surface for this method disappears.

Deleted

ToArgsDictionary, IsAcceptableArgsContainer, _propertyCache
The [UnconditionalSuppressMessage("Trimming", "IL2026"/"IL2070")] attrs
using System.Reflection, System.Collections.Concurrent,
System.Diagnostics.CodeAnalysis (now unused)
The [LocArgs] soft opt-in marker (string-name match in
IsAcceptableArgsContainer)

Migrated callers

Selftest + AppTests localization fixtures (two files)
IntlAccessorTests, RichMessageTests
Reactor.Cli/Loc/SourceRewriter: emits tuple syntax now. CLI codegen
for interpolated strings now writes t.Message(key, ("name", expr))
instead of t.Message(key, new { name = expr }). Updated
SourceRewriterTests assertions.
Docs: _pipeline/templates/localization.md.dt narrative and
_pipeline/apps/localization/App.cs snippets (the compiled
docs/guide/localization.md regenerates from these). Plus the
hand-edited docs/reference/localization-howto.md example.

AOT skip list

Localization_LocaleSwitching removed from DefaultAotSkipPatterns
in SelfTestRunner.cs.
"Localization with anonymous-type args" row removed from
docs/aot-support.md — there''s no anonymous-type path left to break.

Verified

dotnet build src/Reactor — clean (AOT warnings remain as errors).
dotnet test tests/Reactor.Tests --filter "FullyQualifiedName~Localization" — 282/282 pass.
dotnet run --project tests/Reactor.AppTests.Host -- --self-test
(JIT, full suite) — 0 failures.
AOT republish + selftest pending verification on this PR; will report
back with numbers.

Breaking change

t.Message(key, new { name = "..." }) no longer compiles. The compiler
error is reasonably clear ("cannot convert anonymous type to
IDictionary<string, object>"); no analyzer needed. Migration is a
mechanical new { name = X } → ("name", X).

Base

This PR is based on codemonkeychris/aot-selftest-skips-round3
(PR #353). When that merges, GitHub will retarget this PR to main.

Localization_LocaleSwitching now runs under AOT (PR #354), so: 193 skipped -> 192 skipped ~542 passed -> ~543 passed Total fixture count stays at 735. Also drops "anonymous-type localization args" from the documented skip-cluster list since that subsystem is now AOT-clean. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

codemonkeychris · 2026-05-20T15:46:09Z

AOT verification complete.

Full AOT selftest run against the published binary on this branch:

Metric	Before (PR #353)	After this PR
`ok` sub-assertions	2184	2224
`not ok`	0	0
`# SKIP`	193	192
`Localization_LocaleSwitching`	skipped	runs, 40/40 pass

The 40 newly-passing sub-assertions cover Greeting / Plural_Zero / Plural_Five / Search_Zero / Search_One / Search_Many / Direction across en-US, ko-KR, ar-SA, ja-JP, de-DE, plus en-US round-trip. Tuple-params overload behaves identically under AOT and JIT.

Pushed CONTRIBUTING.md count refresh to match (192 skipped, ~543 passed, 0 failed).

Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR removes reflection-based localization argument handling (which breaks under NativeAOT trimming) and replaces it with AOT-safe argument passing via IDictionary<string, object> and tuple-params overloads for Message/RichMessage.

Changes:

Updated IntlAccessor to accept explicit dictionaries and added tuple-params overloads that build args without reflection.
Migrated call sites (tests, fixtures, CLI source rewriter) from anonymous objects to tuple args / dictionaries.
Updated documentation and AOT skip list to reflect the new, AOT-safe localization args model.

Show a summary per file

File	Description
tests/Reactor.Tests/Localization/SourceRewriterTests.cs	Updates assertions to match tuple-arg codegen output.
tests/Reactor.Tests/Localization/RichMessageTests.cs	Switches rich-message args to explicit dictionary.
tests/Reactor.Tests/Localization/IntlAccessorTests.cs	Migrates tests from anonymous args objects to tuple args.
tests/Reactor.AppTests.Host/SelfTest/SelfTestRunner.cs	Removes localization fixture from AOT skip list and updates rationale.
tests/Reactor.AppTests.Host/SelfTest/Fixtures/LocalizationFixtures.cs	Migrates localization fixture calls to tuple args.
tests/Reactor.AppTests.Host/Fixtures/LocalizationFixtures.cs	Migrates app-test fixture calls to tuple args.
src/Reactor/Core/Localization/IntlAccessor.cs	Core API change: dictionary-based args + tuple overloads; removes reflection helpers.
src/Reactor.Cli/Loc/SourceRewriter.cs	Emits tuple-arg syntax instead of anonymous objects.
docs/reference/localization-howto.md	Updates example to use tuple args.
docs/aot-support.md	Removes anonymous-type localization args as an AOT limitation.
docs/_pipeline/templates/localization.md.dt	Updates narrative to describe tuple args as the primary interpolation shape.
docs/_pipeline/apps/localization/App.cs	Updates code snippets to use tuple args.
CONTRIBUTING.md	Updates expected AOT skip/pass counts after removing the localization skip.

Copilot's findings

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Files reviewed: 13/13 changed files
Comments generated: 5

Five inline findings from copilot-pull-request-reviewer: 1. BuildArgs null-skip semantics. Behavior parity with the removed ToArgsDictionary, which dropped null-valued properties so the formatter saw the placeholder as missing rather than substituting "null". Tuple value type is now object?, nulls are skipped before insertion, and a unit test pins the behavior. 2. cref XML doc warnings. The RichMessage <see cref=...> referenced a method signature with C# keyword generics and nullable annotations, which can fail to resolve. Replaced with a prose reference and a <c>RichMessage</c> code element. 3. SourceRewriter param-name escaping (x2). The generator emitted $"(\"{param}\", ...)" without escaping the placeholder name. ICU spec doesn't forbid " or \ in param names — if one slipped through, the emitted source became invalid C#. Now uses SymbolDisplay.FormatLiteral to produce a valid C# string literal. 4. Docs template phrasing. (name, value) reads like a positional tuple with an identifier first item; readers might try .Message(key, (name, value)). Tightened to ("name", value) and added a sentence explaining the first item is the placeholder name as a string literal. Also: ran mur docs compile --skip-screenshots, which regenerated docs/guide/localization.md (template change) and docs/guide/navigation.md (picked up an unrelated drift from the navigation doc app that an earlier commit forgot to regen). Both checked in so docs/guide stays authoritative. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

codemonkeychris · 2026-05-20T16:12:41Z

Addressed all 5 reviewer findings in 615b10f:

BuildArgs null semantics — switched the tuple value type to object?, drop null-valued tuples before they hit the dict (matches the removed ToArgsDictionary''s skip-nulls behavior), added an IntlAccessorTests case pinning it.
cref XML warnings on RichMessage doc — the cref referenced a signature with C# keyword generics + nullability, which doesn''t resolve. Replaced with a prose reference + <c>RichMessage</c>.
SourceRewriter ICU param-name escaping (two comments, same finding) — now uses SymbolDisplay.FormatLiteral(param, quote: true) to produce a valid C# string literal so a placeholder with \" or \\ can''t corrupt the emitted source.
Template phrasing — tightened (name, value) to (\"name\", value) with an explicit sentence that the first item is the placeholder name as a string literal. Regenerated docs/guide/localization.md from the template.

JIT localization tests: 283/283 (the +1 is the new null-skip case).

Localization_LocaleSwitching now runs under AOT (PR #354), so: 193 skipped -> 192 skipped ~542 passed -> ~543 passed Total fixture count stays at 735. Also drops "anonymous-type localization args" from the documented skip-cluster list since that subsystem is now AOT-clean. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Five inline findings from copilot-pull-request-reviewer: 1. BuildArgs null-skip semantics. Behavior parity with the removed ToArgsDictionary, which dropped null-valued properties so the formatter saw the placeholder as missing rather than substituting "null". Tuple value type is now object?, nulls are skipped before insertion, and a unit test pins the behavior. 2. cref XML doc warnings. The RichMessage <see cref=...> referenced a method signature with C# keyword generics and nullable annotations, which can fail to resolve. Replaced with a prose reference and a <c>RichMessage</c> code element. 3. SourceRewriter param-name escaping (x2). The generator emitted $"(\"{param}\", ...)" without escaping the placeholder name. ICU spec doesn't forbid " or \ in param names — if one slipped through, the emitted source became invalid C#. Now uses SymbolDisplay.FormatLiteral to produce a valid C# string literal. 4. Docs template phrasing. (name, value) reads like a positional tuple with an identifier first item; readers might try .Message(key, (name, value)). Tightened to ("name", value) and added a sentence explaining the first item is the placeholder name as a string literal. Also: ran mur docs compile --skip-screenshots, which regenerated docs/guide/localization.md (template change) and docs/guide/navigation.md (picked up an unrelated drift from the navigation doc app that an earlier commit forgot to regen). Both checked in so docs/guide stays authoritative. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…erloads The Message(MessageKey, object?) and RichMessage(MessageKey, object?, ...) overloads built an args dictionary by reflecting over public properties of the passed object — anonymous types or [LocArgs]-marked records. Under NativeAOT the trimmer keeps the ctor + backing fields of the anonymous type (both reachable from the ew { … } call site) but drops the property getters, because nothing statically reads them. GetProperties() then returned an empty array, MessageFormat threw on {name}, the catch swallowed the exception, and the raw ICU pattern leaked through to the UI. This change removes the reflection path entirely and gives callers two AOT-safe shapes: - Message(MessageKey, IDictionary<string, object>?) — explicit dict for cases that already have one (or want to share/build one programmatically). - Message(MessageKey, (string Name, object Value) arg1, params (string Name, object Value)[] more) — compact tuple syntax for the common inline case. ValueTuple is a nominal type with concrete fields; building a Dictionary<string,object> from tuple values needs zero reflection. Same shape for RichMessage. (RichMessage with tags uses the dict overload — params must come last, so the tuple variant can't carry the optional ags argument.) Deleted: - ToArgsDictionary + IsAcceptableArgsContainer + _propertyCache - The IL2026/IL2070 unconditional-suppression attributes those needed - System.Reflection + System.Collections.Concurrent + System.Diagnostics.CodeAnalysis usings (now unused) Migrated callers: - Selftest + AppTests localization fixtures (two files) - IntlAccessorTests, RichMessageTests - SourceRewriter CLI codegen: .Message(key, new { name = expr }) → .Message(key, ("name", expr)). Updated SourceRewriterTests. - Docs: _pipeline/templates/localization.md.dt narrative and _pipeline/apps/localization/App.cs snippets, plus the hand-edited docs/reference/localization-howto.md example. Removed from AOT skip list / docs: - Localization_LocaleSwitching no longer needs to be skipped under AOT ( ests/Reactor.AppTests.Host/SelfTest/SelfTestRunner.cs). - The "Localization with anonymous-type args" row in docs/aot-support.md is gone — there's no anonymous-type path left. Verified: - dotnet build src/Reactor clean (AOT warnings as errors). - 282 localization unit tests pass. - Full JIT selftest: 0 failures. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Localization_LocaleSwitching now runs under AOT (PR #354), so: 193 skipped -> 192 skipped ~542 passed -> ~543 passed Total fixture count stays at 735. Also drops "anonymous-type localization args" from the documented skip-cluster list since that subsystem is now AOT-clean. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Five inline findings from copilot-pull-request-reviewer: 1. BuildArgs null-skip semantics. Behavior parity with the removed ToArgsDictionary, which dropped null-valued properties so the formatter saw the placeholder as missing rather than substituting "null". Tuple value type is now object?, nulls are skipped before insertion, and a unit test pins the behavior. 2. cref XML doc warnings. The RichMessage <see cref=...> referenced a method signature with C# keyword generics and nullable annotations, which can fail to resolve. Replaced with a prose reference and a <c>RichMessage</c> code element. 3. SourceRewriter param-name escaping (x2). The generator emitted $"(\"{param}\", ...)" without escaping the placeholder name. ICU spec doesn't forbid " or \ in param names — if one slipped through, the emitted source became invalid C#. Now uses SymbolDisplay.FormatLiteral to produce a valid C# string literal. 4. Docs template phrasing. (name, value) reads like a positional tuple with an identifier first item; readers might try .Message(key, (name, value)). Tightened to ("name", value) and added a sentence explaining the first item is the placeholder name as a string literal. Also: ran mur docs compile --skip-screenshots, which regenerated docs/guide/localization.md (template change) and docs/guide/navigation.md (picked up an unrelated drift from the navigation doc app that an earlier commit forgot to regen). Both checked in so docs/guide stays authoritative. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

codemonkeychris requested a review from Copilot May 20, 2026 15:47

Copilot AI reviewed May 20, 2026

View reviewed changes

Base automatically changed from codemonkeychris/aot-selftest-skips-round3 to main May 20, 2026 16:23

codemonkeychris force-pushed the codemonkeychris/loc-tuple-args branch from 615b10f to 3cb6a07 Compare May 20, 2026 16:25

codemonkeychris and others added 3 commits May 20, 2026 09:39

codemonkeychris force-pushed the codemonkeychris/loc-tuple-args branch from 3cb6a07 to 290eca6 Compare May 20, 2026 16:43

Copilot started reviewing on behalf of codemonkeychris May 20, 2026 16:43 View session

codemonkeychris merged commit 3c3bed9 into main May 20, 2026
9 checks passed

codemonkeychris deleted the codemonkeychris/loc-tuple-args branch May 20, 2026 17:46

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loc: replace reflection-based args with tuple-params + IDictionary overloads#354

loc: replace reflection-based args with tuple-params + IDictionary overloads#354
codemonkeychris merged 3 commits into
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codemonkeychris commented May 20, 2026

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Pull request overview

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