versioning - fixes crash when spreading incompatible versioned model …

…as parameter to operation (microsoft#3951)

Fixes microsoft#3648

Co-authored-by: Christopher Radek <Christopher.Radek@microsoft.com>

.chronus/changes/fix-crash-spread-versioning-2024-6-23-14-37-28.md

@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/versioning"
+---
+
+Fixes issue where spreading a versioned model as a parameter to an incompatible versioned operation would cause the compiler to crash.

packages/versioning/src/validate.ts

@@ -104,6 +104,11 @@ export function $onValidate(program: Program) {
           validateTargetVersionCompatible(program, op.interface, op, { isTargetADependent: true });
         }
         validateReference(program, op, op.returnType);
+
+        // Check that any spread/is/aliased models are valid for this operation
+        for (const sourceModel of op.parameters.sourceModels) {
+          validateReference(program, op, sourceModel.model);
+        }
       },
       interface: (iface) => {
         for (const source of iface.sourceInterfaces) {

packages/versioning/test/incompatible-versioning.test.ts

@@ -131,6 +131,24 @@ describe("versioning: validate incompatible references", () => {
       );
     });
 
+    it("emit diagnostic when versioned op has a newer versioned spread parameter", async () => {
+      const diagnostics = await runner.diagnose(`
+        @added(Versions.v2)
+        model MyOptions {
+          prop: string;
+        }
+        
+        @added(Versions.v1)
+        op foo(...MyOptions,): void;
+        `);
+
+      expectDiagnostics(diagnostics, {
+        code: "@typespec/versioning/incompatible-versioned-reference",
+        message:
+          "'TestService.foo' was added in version 'v1' but referencing type 'TestService.MyOptions' added in version 'v2'.",
+      });
+    });
+
     // TODO See: https://github.com/microsoft/typespec/issues/2695
     it.skip("emit diagnostic when unversioned op based on a template has a versioned model as a parameter", async () => {
       const diagnostics = await runner.diagnose(`