Fix #221: improve diagnostics when dereference fails

In some cases, when a type could not be referenced, the diagnostic message doesn't indicate that (the undefined return value will still cause an error, but we also want to know that we couldn't deref the type)
aws · Sep 12, 2018 · fc805f9 · fc805f9
1 parent e80a889
commit fc805f9
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Showing 2 changed files with 31 additions and 12 deletions.
diff --git a/packages/jsii/lib/assembler.ts b/packages/jsii/lib/assembler.ts
@@ -162,14 +162,21 @@ export class Assembler implements Emitter {
      *
      * @returns the de-referenced type, if it was found, otherwise ``undefined``.
      */
-    private _dereference(ref: spec.NamedTypeReference): spec.Type | undefined {
+    private _dereference(ref: spec.NamedTypeReference, referencingNode: ts.Node): spec.Type | undefined {
         const [assm, ] = ref.fqn.split('.');
+        let type;
         if (assm === this.projectInfo.name) {
-            return this._types[ref.fqn];
+            type = this._types[ref.fqn];
         } else {
             const assembly = this.projectInfo.transitiveDependencies.find(dep => dep.name === assm);
-            return assembly && assembly.types && assembly.types[ref.fqn];
+            type = assembly && assembly.types && assembly.types[ref.fqn];
         }
+
+        if (!type) {
+            this._diagnostic(referencingNode, ts.DiagnosticCategory.Error, `Unable to resolve referenced type '${ref.fqn}'. Missing export?`);
+        }
+
+        return type;
     }
 
     private _diagnostic(node: ts.Node | null, category: ts.DiagnosticCategory, messageText: string) {
@@ -206,7 +213,7 @@ export class Assembler implements Emitter {
             return `unknown.${typeName}`;
         }
         const fqn = `${pkg.name}.${typeName}`;
-        if (pkg.name !== this.projectInfo.name && !this._dereference({ fqn })) {
+        if (pkg.name !== this.projectInfo.name && !this._dereference({ fqn }, type.symbol.valueDeclaration)) {
             this._diagnostic(type.symbol.valueDeclaration,
                              ts.DiagnosticCategory.Error,
                              `Use of foreign type not present in the ${pkg.name}'s assembly: ${fqn}`);
@@ -314,10 +321,10 @@ export class Assembler implements Emitter {
                 continue;
             }
             this._defer(() => {
-                if (!spec.isClassType(this._dereference(ref))) {
+                if (!spec.isClassType(this._dereference(ref, base.symbol.valueDeclaration))) {
                     this._diagnostic(base.symbol.valueDeclaration,
                                     ts.DiagnosticCategory.Error,
-                                    `Base type of ${jsiiType.fqn} is not a class (${spec.describeTypeReference(ref)})`);
+                                    `Base type of ${jsiiType.fqn} is not a class or cannot be dereferenced (${spec.describeTypeReference(ref)})`);
                 }
             });
             jsiiType.base = ref;
@@ -340,7 +347,7 @@ export class Assembler implements Emitter {
                     continue;
                 }
                 this._defer(() => {
-                    if (!spec.isInterfaceType(this._dereference(typeRef))) {
+                    if (!spec.isInterfaceType(this._dereference(typeRef, expression))) {
                         this._diagnostic(expression,
                                         ts.DiagnosticCategory.Error,
                                         `Implements clause of ${jsiiType.fqn} uses ${spec.describeTypeReference(typeRef)} as an interface`);
@@ -393,7 +400,7 @@ export class Assembler implements Emitter {
             }
         } else if (jsiiType.base) {
             this._defer(() => {
-                const baseType = this._dereference(jsiiType.base!);
+                const baseType = this._dereference(jsiiType.base!, type.symbol.valueDeclaration);
                 if (!baseType) {
                     this._diagnostic(type.symbol.valueDeclaration,
                                     ts.DiagnosticCategory.Error,
@@ -403,7 +410,7 @@ export class Assembler implements Emitter {
                 } else {
                     this._diagnostic(type.symbol.valueDeclaration,
                         ts.DiagnosticCategory.Error,
-                        `Base type of ${jsiiType.fqn} (${jsiiType.base!.fqn}) is not a class`);
+                        `Base type of ${jsiiType.fqn} (${jsiiType.base!.fqn}) is not a class or cannot be dereferenced`);
                 }
             });
         } else {
@@ -499,12 +506,14 @@ export class Assembler implements Emitter {
                 continue;
             }
             this._defer(() => {
-                if (!spec.isInterfaceType(this._dereference(ref))) {
-                    const baseType = this._dereference(ref);
+                const baseType = this._dereference(ref, base.symbol.valueDeclaration);
+                if (!spec.isInterfaceType(baseType)) {
                     if (baseType) {
+                        // tslint:disable:max-line-length
                         this._diagnostic(base.symbol.valueDeclaration,
                                         ts.DiagnosticCategory.Error,
-                                        `Base type of ${jsiiType.fqn} is not an interface (${baseType.kind} ${spec.describeTypeReference(ref)})`);
+                                        `Base type of ${jsiiType.fqn} is not an interface or cannot be dereferenced (${baseType.kind} ${spec.describeTypeReference(ref)})`);
+                        // tslint:enable:max-line-length
                     } else {
                         this._diagnostic(base.symbol.valueDeclaration,
                             ts.DiagnosticCategory.Error,

diff --git a/packages/jsii/test/negatives/neg.deref-error.ts b/packages/jsii/test/negatives/neg.deref-error.ts
@@ -0,0 +1,10 @@
+///!MATCH_ERROR: Unable to resolve referenced type 'Base'. Missing export?
+///!MATCH_ERROR: Base type of jsii.Derived is not a class or cannot be dereferenced (Base)
+
+class Base {
+
+}
+
+export class Derived extends Base {
+
+}