Validate that model and model are not model expression (#1004)

common/changes/@cadl-lang/compiler/validate-model-is-extends-expr_2022-09-08-16-09.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@cadl-lang/compiler",
+      "comment": "**Breaking** Model `extends` or `is` canot reference a model expression.",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@cadl-lang/compiler"
+}

packages/compiler/core/checker.ts

@@ -2191,6 +2191,14 @@ export function createChecker(program: Program): Checker {
     heritageRef: Expression,
     mapper: TypeMapper | undefined
   ): Model | undefined {
+    if (heritageRef.kind === SyntaxKind.ModelExpression) {
+      reportDiagnostic(program, {
+        code: "extend-model",
+        messageId: "modelExpression",
+        target: heritageRef,
+      });
+      return undefined;
+    }
     if (heritageRef.kind !== SyntaxKind.TypeReference) {
       reportDiagnostic(program, {
         code: "extend-model",
@@ -2228,6 +2236,14 @@ export function createChecker(program: Program): Checker {
       return undefined;
     }
 
+    if (heritageType.name === "") {
+      reportDiagnostic(program, {
+        code: "extend-model",
+        messageId: "modelExpression",
+        target: heritageRef,
+      });
+    }
+
     if (isIntrinsic(program, heritageType)) {
       program.reportDiagnostic(
         createDiagnostic({
@@ -2254,7 +2270,14 @@ export function createChecker(program: Program): Checker {
     const modelSymId = getNodeSymId(model);
     pendingResolutions.add(modelSymId);
     let isType;
-    if (isExpr.kind === SyntaxKind.ArrayExpression) {
+    if (isExpr.kind === SyntaxKind.ModelExpression) {
+      reportDiagnostic(program, {
+        code: "is-model",
+        messageId: "modelExpression",
+        target: isExpr,
+      });
+      return undefined;
+    } else if (isExpr.kind === SyntaxKind.ArrayExpression) {
       isType = checkArrayExpression(isExpr, mapper);
     } else if (isExpr.kind === SyntaxKind.TypeReference) {
       const target = resolveTypeReference(isExpr, mapper);
@@ -2284,6 +2307,10 @@ export function createChecker(program: Program): Checker {
       return;
     }
 
+    if (isType.name === "") {
+      reportDiagnostic(program, { code: "is-model", messageId: "modelExpression", target: isExpr });
+    }
+
     return isType;
   }
 

packages/compiler/core/messages.ts

@@ -282,6 +282,7 @@ const diagnostics = {
     severity: "error",
     messages: {
       default: "Models must extend other models.",
+      modelExpression: "Models cannot extend model expressions.",
     },
   },
   "extend-primitive": {
@@ -294,6 +295,7 @@ const diagnostics = {
     severity: "error",
     messages: {
       default: "Model `is` must specify another model.",
+      modelExpression: "Model `is` cannot specify a model expression.",
     },
   },
   "is-operation": {

packages/compiler/test/checker/model.test.ts

@@ -318,6 +318,35 @@ describe("compiler: models", () => {
       });
     });
 
+    it("emit error when extend model expression", async () => {
+      testHost.addCadlFile(
+        "main.cadl",
+        `
+        model A extends {name: string} {}
+        `
+      );
+      const diagnostics = await testHost.diagnose("main.cadl");
+      expectDiagnostics(diagnostics, {
+        code: "extend-model",
+        message: "Models cannot extend model expressions.",
+      });
+    });
+
+    it("emit error when extend model expression via alias", async () => {
+      testHost.addCadlFile(
+        "main.cadl",
+        `
+        alias B = {name: string};
+        model A extends B {}
+        `
+      );
+      const diagnostics = await testHost.diagnose("main.cadl");
+      expectDiagnostics(diagnostics, {
+        code: "extend-model",
+        message: "Models cannot extend model expressions.",
+      });
+    });
+
     it("emit error when extends itself", async () => {
       testHost.addCadlFile(
         "main.cadl",
@@ -475,6 +504,35 @@ describe("compiler: models", () => {
       });
     });
 
+    it("emit error when is model expression", async () => {
+      testHost.addCadlFile(
+        "main.cadl",
+        `
+        model A is {name: string} {}
+        `
+      );
+      const diagnostics = await testHost.diagnose("main.cadl");
+      expectDiagnostics(diagnostics, {
+        code: "is-model",
+        message: "Model `is` cannot specify a model expression.",
+      });
+    });
+
+    it("emit error when is model expression via alias", async () => {
+      testHost.addCadlFile(
+        "main.cadl",
+        `
+        alias B = {name: string};
+        model A is B {}
+        `
+      );
+      const diagnostics = await testHost.diagnose("main.cadl");
+      expectDiagnostics(diagnostics, {
+        code: "is-model",
+        message: "Model `is` cannot specify a model expression.",
+      });
+    });
+
     it("emit error when is itself", async () => {
       testHost.addCadlFile(
         "main.cadl",