From 7b137bea061178d799d110ebdb501ebc9e4c81c6 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Wed, 8 Dec 2021 14:29:28 +0100
Subject: [PATCH] At least *propagate* unhandlable-binder-guard errors

---
 packages/compiler/src/compiler/codegen.ts | 20 +++++++++++++-------
 packages/syndicatec/src/cli.ts            | 10 ++++++++++
 packages/ts-plugin/src/index.ts           |  4 ++++
 packages/tsc/src/tsc.ts                   |  4 ++++
 4 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/packages/compiler/src/compiler/codegen.ts b/packages/compiler/src/compiler/codegen.ts
index 82537fc..fc7f9d1 100644
--- a/packages/compiler/src/compiler/codegen.ts
+++ b/packages/compiler/src/compiler/codegen.ts
@@ -29,6 +29,8 @@ export function stripShebang(items: Items): Items {
 
 export type ModuleType ='es6' | 'require' | 'global';
 
+export type ErrorSink = (message: string) => void;
+
 export interface CompileOptions {
     source: string,
     name?: string,
@@ -36,6 +38,7 @@ export interface CompileOptions {
     module?: ModuleType,
     global?: string,
     typescript?: boolean,
+    emitError: ErrorSink,
 }
 
 export interface CompilerOutput {
@@ -49,14 +52,17 @@ export class ExpansionContext {
     readonly parser: SyndicateParser;
     readonly moduleType: ModuleType;
     readonly typescript: boolean;
+    readonly emitError: (message: string) => void;
     nextIdNumber = 0;
 
     constructor(moduleType: ModuleType,
-                typescript: boolean)
+                typescript: boolean,
+                emitError: ErrorSink)
     {
         this.parser = typescript ? new SyndicateTypedParser : new SyndicateParser();
         this.moduleType = moduleType;
         this.typescript = typescript;
+        this.emitError = emitError;
     }
 
     quasiRandomId(): string {
@@ -72,7 +78,7 @@ function stringifyId(i: Identifier): Items {
     return [ { ... i, type: TokenType.STRING, text: JSON.stringify(i.text) } ];
 }
 
-function binderTypeGuard(t: TemplateFunction): (binder: Binder, index: number) => Items {
+function binderTypeGuard(ctx: ExpansionContext, t: TemplateFunction): (binder: Binder, index: number) => Items {
     return (binder, index) => {
         if (binder.id.text[0] === '_') {
             return t`${`/* Ignoring underscore-prefixed binder ${binder.id.text} */`}`;
@@ -93,8 +99,8 @@ function binderTypeGuard(t: TemplateFunction): (binder: Binder, index: number) =
                 case 'any':
                     return bind;
                 default:
-                    // TODO: something better than this!!
-                    throw new Error(`Unhandled binding type: ${JSON.stringify(typeText)}`);
+                    ctx.emitError(`Cannot emit guard for binding of type: ${JSON.stringify(typeText)}`);
+                    return bind; /* act as if "any", for now */
             }
         }
     };
@@ -136,7 +142,7 @@ export function expand(tree: Items, ctx: ExpansionContext): Items {
                 observer: __SYNDICATE__.Turn.ref(__SYNDICATE__.assertionFacetObserver(
                     (${ctx.argDecl(t, '__vs', '__SYNDICATE__.AnyValue')}) => {
                         if (Array.isArray(__vs)) {
-${joinItems(sa.captureBinders.map(binderTypeGuard(t)), '\n')}
+${joinItems(sa.captureBinders.map(binderTypeGuard(ctx, t)), '\n')}
                             ${walk(s.body)}
                         }
                     }
@@ -202,7 +208,7 @@ ${joinItems(sa.captureBinders.map(binderTypeGuard(t)), '\n')}
 
         const sa = compilePattern(s.pattern);
         const guardBody = (body: Statement) => t`if (Array.isArray(__vs)) {
-${joinItems(sa.captureBinders.map(binderTypeGuard(t)), '\n')}
+${joinItems(sa.captureBinders.map(binderTypeGuard(ctx, t)), '\n')}
             ${body}
         }`;
 
@@ -281,7 +287,7 @@ export function compile(options: CompileOptions): CompilerOutput {
 
     const macro = new Templates(undefined, { extraDelimiters: ':' });
 
-    const ctx = new ExpansionContext(moduleType, typescript);
+    const ctx = new ExpansionContext(moduleType, typescript, options.emitError);
 
     tree = expand(tree, ctx);
 
diff --git a/packages/syndicatec/src/cli.ts b/packages/syndicatec/src/cli.ts
index 9a02bd9..ea17ecc 100644
--- a/packages/syndicatec/src/cli.ts
+++ b/packages/syndicatec/src/cli.ts
@@ -117,6 +117,8 @@ export function main(argv: string[]) {
                  argv => argv)
         .argv);
 
+    const collectedErrors: Array<string> = [];
+
     const rename = makeRenamer(options.outputDirectory ?? '',
                                options.rootDirectory ?? '.',
                                options.rename);
@@ -144,6 +146,10 @@ export function main(argv: string[]) {
             runtime: options.runtime,
             module: options.module,
             typescript: options.typed,
+            emitError: m => {
+                console.error(m);
+                collectedErrors.push(m);
+            }
         });
         map.sourcesContent = [source];
 
@@ -161,4 +167,8 @@ export function main(argv: string[]) {
             fs.writeFileSync(outputFilename, text + sourceMappingComment(dataURL(JSON.stringify(map))));
         }
     }
+
+    if (collectedErrors.length > 0) {
+        throw new Error(`Compilation failed with ${collectedErrors.length} error(s).`);
+    }
 }
diff --git a/packages/ts-plugin/src/index.ts b/packages/ts-plugin/src/index.ts
index 1e30192..bc35117 100644
--- a/packages/ts-plugin/src/index.ts
+++ b/packages/ts-plugin/src/index.ts
@@ -164,6 +164,10 @@ const boot: tslib.server.PluginModuleFactory = ({ typescript: ts }) => {
                             source: inputText,
                             name: fileName,
                             typescript: true,
+                            emitError: m => {
+                                console.error(m);
+                                onError?.(m);
+                            },
                         });
                         const sf = ts.createSourceFile(fileName, expandedText, languageVersion, true);
                         syndicateInfo.set(fileName, {
diff --git a/packages/tsc/src/tsc.ts b/packages/tsc/src/tsc.ts
index c93ca4c..729f17b 100644
--- a/packages/tsc/src/tsc.ts
+++ b/packages/tsc/src/tsc.ts
@@ -150,6 +150,10 @@ function runBuildOnce(options: CommandLineArguments, toWatch = new ToWatch()) {
                             source: inputText,
                             name: fileName,
                             typescript: true,
+                            emitError: m => {
+                                console.error(m);
+                                onError?.(m);
+                            },
                         });
                         writeIntermediate(fileName, expandedText);
                         syndicateInfo.set(fileName, {