From 40993195b8da0d042161a7b7bb0f6831dcfb4da1 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Wed, 13 May 2020 15:14:43 -0700
Subject: [PATCH] Fix wasm tests on CI (#616)

* wasm: Improve error message on missing language symbol

* Fix source file existence checks in build-wasm command
---
 cli/src/wasm.rs            | 6 +++---
 lib/binding_web/binding.js | 6 +++++-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/cli/src/wasm.rs b/cli/src/wasm.rs
index 8c123e3b..47cea90a 100644
--- a/cli/src/wasm.rs
+++ b/cli/src/wasm.rs
@@ -89,11 +89,11 @@ pub fn compile_language_to_wasm(language_dir: &Path, force_docker: bool) -> Resu
     let scanner_cc_path = src.join("scanner.cc");
     let scanner_cpp_path = src.join("scanner.cpp");
 
-    if scanner_cc_path.exists() {
+    if language_dir.join(&scanner_cc_path).exists() {
         command.arg("-xc++").arg(&scanner_cc_path);
-    } else if scanner_cpp_path.exists() {
+    } else if language_dir.join(&scanner_cpp_path).exists() {
         command.arg("-xc++").arg(&scanner_cpp_path);
-    } else if scanner_c_path.exists() {
+    } else if language_dir.join(&scanner_c_path).exists() {
         command.arg(&scanner_c_path);
     }
 
diff --git a/lib/binding_web/binding.js b/lib/binding_web/binding.js
index feedb37f..eb6d4d8a 100644
--- a/lib/binding_web/binding.js
+++ b/lib/binding_web/binding.js
@@ -872,10 +872,14 @@ class Language {
     return bytes
       .then(bytes => loadWebAssemblyModule(bytes, {loadAsync: true}))
       .then(mod => {
-        const functionName = Object.keys(mod).find(key =>
+        const symbolNames = Object.keys(mod)
+        const functionName = symbolNames.find(key =>
           LANGUAGE_FUNCTION_REGEX.test(key) &&
           !key.includes("external_scanner_")
         );
+        if (!functionName) {
+          console.log(`Couldn't find language function in WASM file. Symbols:\n${JSON.stringify(symbolNames, null, 2)}`)
+        }
         const languageAddress = mod[functionName]();
         return new Language(INTERNAL, languageAddress);
       });