suppress "unknown x" errors from productions defined in external biblios (#434)

Author: bakkot

src/lint/collect-grammar-diagnostics.ts

@@ -73,9 +73,18 @@ export async function collectGrammarDiagnostics(
           }
           const paramToError = unusedParameterErrors.get(nodeName)!;
           paramToError.set(paramName, error);
-        } else {
-          report(error);
+          return;
         }
+        if (
+          m.code === Diagnostics.Cannot_find_name_0_.code &&
+          spec.biblio.byProductionName(m.messageArguments?.[0]) != null
+        ) {
+          // grammarkdown assumes it has the whole grammar in scope
+          // but some productions might be defined in an external biblio
+          // TODO: thread the actual grammar through to grammarkdown so it has appropriate context, instead of surpressing this error
+          return;
+        }
+        report(error);
       });
   }
 
@@ -118,6 +127,12 @@ export async function collectGrammarDiagnostics(
     for (const [name, { production, rhses }] of productions) {
       const originalRhses = actualGrammarProductions.get(name)?.rhses;
       if (originalRhses === undefined) {
+        if (spec.biblio.byProductionName(name) != null) {
+          // in an ideal world we'd keep the full grammar in the biblio so we could check for a matching RHS, not just a matching LHS
+          // but, we're not in that world
+          // https://github.com/tc39/ecmarkup/issues/431
+          continue;
+        }
         const { line, column } = getLocationInGrammar(grammar, production.pos);
         report({
           type: 'contents',

test/errors.js

@@ -3,7 +3,13 @@
 let assert = require('assert');
 let emu = require('../lib/ecmarkup');
 
-let { lintLocationMarker: M, positioned, assertError, assertErrorFree } = require('./utils.js');
+let {
+  lintLocationMarker: M,
+  positioned,
+  assertError,
+  assertErrorFree,
+  getBiblio,
+} = require('./utils.js');
 
 describe('errors', () => {
   it('no contributors', async () => {
@@ -1002,23 +1008,11 @@ ${M}      </pre>
     });
 
     it('negative: external biblio', async () => {
-      let upstream = await emu.build(
-        'root.html',
-        () => `
-          <emu-grammar type="definition">
-            Foo : \`a\`
-          </emu-grammar>
-        `,
-        {
-          copyright: false,
-          location: 'https://example.com/spec/',
-          warn: e => {
-            console.error('Error:', e);
-            throw new Error(e.message);
-          },
-        }
-      );
-      let upstreamBiblio = upstream.exportBiblio();
+      let upstream = await getBiblio(`
+        <emu-grammar type="definition">
+          Foo : \`a\`
+        </emu-grammar>
+      `);
 
       await assertErrorFree(
         `
@@ -1034,7 +1028,7 @@ ${M}      </pre>
           </emu-clause>
         `,
         {
-          extraBiblios: [upstreamBiblio],
+          extraBiblios: [upstream],
         }
       );
     });

test/lint.js

@@ -1,6 +1,12 @@
 'use strict';
 
-let { assertLint, assertLintFree, positioned, lintLocationMarker: M } = require('./utils.js');
+let {
+  assertLint,
+  assertLintFree,
+  positioned,
+  lintLocationMarker: M,
+  getBiblio,
+} = require('./utils.js');
 
 describe('linting whole program', () => {
   describe('grammar validity', () => {
@@ -67,6 +73,40 @@ describe('linting whole program', () => {
         }
       );
     });
+
+    it('unknown nonterminal', async () => {
+      await assertLint(
+        positioned`
+          <emu-grammar type="definition">
+            Foo: ${M}Bar
+          </emu-grammar>
+        `,
+        {
+          ruleId: 'grammarkdown:2000',
+          nodeType: 'emu-grammar',
+          message: "Cannot find name: 'Bar'.",
+        }
+      );
+    });
+
+    it('negative: nonterminal defined upstream', async () => {
+      let upstream = await getBiblio(`
+        <emu-grammar type="definition">
+          Bar: \`a\`
+        </emu-grammar>
+      `);
+
+      await assertLintFree(
+        `
+          <emu-grammar type="definition">
+            Foo: Bar
+          </emu-grammar>
+        `,
+        {
+          extraBiblios: [upstream],
+        }
+      );
+    });
   });
 
   describe('early error shape', () => {
@@ -210,6 +250,28 @@ describe('linting whole program', () => {
         }
       );
     });
+
+    it('negative: productions defined in biblio', async () => {
+      let upstream = await getBiblio(`
+        <emu-grammar type="definition">
+          Statement: EmptyStatement
+        </emu-grammar>
+      `);
+
+      await assertLintFree(
+        `
+          <emu-grammar>
+            Statement: EmptyStatement
+          </emu-grammar>
+          <emu-alg>
+            1. Return Foo.
+          </emu-alg>
+        `,
+        {
+          extraBiblios: [upstream],
+        }
+      );
+    });
   });
 
   describe('header format', () => {

test/utils.js

@@ -105,6 +105,11 @@ async function assertError(obj, { ruleId, nodeType, message }, opts) {
 }
 
 async function assertErrorFree(html, opts) {
+  if (typeof html !== 'string') {
+    throw new Error(
+      "assertErrorFree expects a string; did you forget to remove the 'positioned' tag?"
+    );
+  }
   let warnings = [];
 
   await emu.build('test-example.emu', async () => html, {
@@ -121,8 +126,15 @@ async function assertLint(a, b) {
   await assertError(a, b, { lintSpec: true });
 }
 
-async function assertLintFree(html) {
-  await assertErrorFree(html, { lintSpec: true });
+async function assertLintFree(html, opts = {}) {
+  await assertErrorFree(html, { lintSpec: true, ...opts });
+}
+
+async function getBiblio(html) {
+  let upstream = await emu.build('root.html', () => html, {
+    location: 'https://example.com/spec/',
+  });
+  return upstream.exportBiblio();
 }
 
 module.exports = {
@@ -132,4 +144,5 @@ module.exports = {
   assertErrorFree,
   assertLint,
   assertLintFree,
+  getBiblio,
 };