From 4f8caae8fc59816163178b8c786792acbd5bef11 Mon Sep 17 00:00:00 2001
From: Timothee Guerin <timothee.guerin@outlook.com>
Date: Mon, 29 Apr 2024 13:29:55 -0700
Subject: [PATCH] Allow @pattern to be provided on a scalar (#751)

fix [#732](https://github.com/Azure/typespec-azure/issues/732)
---
 .../fix-allow-scalars-2024-3-26-23-13-19.md   |  8 +++++++
 .../src/rules/arm-resource-name-pattern.ts    | 19 +++++++++++++--
 .../rules/arm-resource-name-pattern.test.ts   | 23 ++++++++++++++++++-
 3 files changed, 47 insertions(+), 3 deletions(-)
 create mode 100644 .chronus/changes/fix-allow-scalars-2024-3-26-23-13-19.md

diff --git a/.chronus/changes/fix-allow-scalars-2024-3-26-23-13-19.md b/.chronus/changes/fix-allow-scalars-2024-3-26-23-13-19.md
new file mode 100644
index 0000000000..d963bf1ba4
--- /dev/null
+++ b/.chronus/changes/fix-allow-scalars-2024-3-26-23-13-19.md
@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@azure-tools/typespec-azure-resource-manager"
+---
+
+Allow `@pattern` to be provided on a scalar
diff --git a/packages/typespec-azure-resource-manager/src/rules/arm-resource-name-pattern.ts b/packages/typespec-azure-resource-manager/src/rules/arm-resource-name-pattern.ts
index 804a2e221d..4db6f20be1 100644
--- a/packages/typespec-azure-resource-manager/src/rules/arm-resource-name-pattern.ts
+++ b/packages/typespec-azure-resource-manager/src/rules/arm-resource-name-pattern.ts
@@ -1,5 +1,6 @@
 import {
   DiagnosticTarget,
+  ModelProperty,
   Program,
   SourceLocation,
   createRule,
@@ -59,8 +60,7 @@ export const armResourceNamePatternRule = createRule({
           // find the name property
           const nameProperty = resource.typespecType.properties.get("name");
           if (nameProperty !== undefined) {
-            const pattern = getPattern(program, nameProperty);
-            if (pattern === undefined) {
+            if (!hasPattern(program, nameProperty)) {
               context.reportDiagnostic({
                 target: nameProperty,
                 codefixes: [createPatternCodeFix(nameProperty)],
@@ -72,3 +72,18 @@ export const armResourceNamePatternRule = createRule({
     };
   },
 });
+
+function hasPattern(program: Program, property: ModelProperty): boolean {
+  const pattern = getPattern(program, property);
+  if (pattern !== undefined) {
+    return true;
+  }
+
+  if (property.type.kind === "Scalar") {
+    const pattern = getPattern(program, property.type);
+    if (pattern !== undefined) {
+      return true;
+    }
+  }
+  return false;
+}
diff --git a/packages/typespec-azure-resource-manager/test/rules/arm-resource-name-pattern.test.ts b/packages/typespec-azure-resource-manager/test/rules/arm-resource-name-pattern.test.ts
index f5a96a860c..bbd416ce78 100644
--- a/packages/typespec-azure-resource-manager/test/rules/arm-resource-name-pattern.test.ts
+++ b/packages/typespec-azure-resource-manager/test/rules/arm-resource-name-pattern.test.ts
@@ -94,7 +94,6 @@ it("Does not emit a warning for an ARM resource that specifies `@pattern` on the
     namespace Microsoft.Contoso;
     
     model Employee is ProxyResource<{}> {
-      @doc("Name of employee")
       @pattern("^[a-zA-Z0-9-]{3,24}$")
       @key("employeeName")
       @path
@@ -114,3 +113,25 @@ it("Does not emit a warning for an ARM resource that specifies `@pattern` on the
     )
     .toBeValid();
 });
+
+it("Does not emit a warning for an ARM resource that specifies `@pattern` on the on the scalar used", async () => {
+  await tester
+    .expect(
+      `
+    @armProviderNamespace
+    @useDependency(Azure.ResourceManager.Versions.v1_0_Preview_1)
+    namespace Microsoft.Contoso;
+
+    @pattern("^[a-zA-Z0-9][a-zA-Z0-9-]{1,58}[a-zA-Z0-9]$")
+    scalar stringResourceName extends string;
+
+    model Employee is ProxyResource<{}> {
+      @key("employeeName")
+      @path
+      @segment("employees")
+      name: stringResourceName;
+    }
+    `
+    )
+    .toBeValid();
+});