Provide a better error message when language is not recognised

lib/config-utils.js

@@ -23,6 +23,13 @@ const QUERIES_PROPERTY = 'queries';
 const QUERIES_USES_PROPERTY = 'uses';
 const PATHS_IGNORE_PROPERTY = 'paths-ignore';
 const PATHS_PROPERTY = 'paths';
+// All the languages supported by CodeQL
+const ALL_LANGUAGES = ['csharp', 'cpp', 'go', 'java', 'javascript', 'python'];
+// Some alternate names for languages
+const LANGUAGE_ALIASES = {
+    'c': 'cpp',
+    'typescript': 'javascript',
+};
 /**
  * A list of queries from https://github.com/github/codeql that
  * we don't want to run. Disabling them here is a quicker alternative to
@@ -350,7 +357,28 @@ async function getLanguages() {
         throw new Error("Did not detect any languages to analyze. " +
             "Please update input in workflow or check that GitHub detects the correct languages in your repository.");
     }
-    return languages;
+    // Make sure they are supported
+    const checkedLanguages = [];
+    const unknownLanguages = [];
+    for (let language of languages) {
+        // Normalise to lower case
+        language = language.toLowerCase();
+        // Resolve any known aliases
+        if (language in LANGUAGE_ALIASES) {
+            language = LANGUAGE_ALIASES[language];
+        }
+        const checkedLanguage = ALL_LANGUAGES.find(l => l === language);
+        if (checkedLanguage === undefined) {
+            unknownLanguages.push(language);
+        }
+        else if (checkedLanguages.indexOf(checkedLanguage) === -1) {
+            checkedLanguages.push(checkedLanguage);
+        }
+    }
+    if (unknownLanguages.length > 0) {
+        throw new Error("Did not recognise the following languages: " + unknownLanguages.join(', '));
+    }
+    return checkedLanguages;
 }
 /**
  * Get the default config for when the user has not supplied one.

src/config-utils.ts

@@ -17,6 +17,16 @@ const QUERIES_USES_PROPERTY = 'uses';
 const PATHS_IGNORE_PROPERTY = 'paths-ignore';
 const PATHS_PROPERTY = 'paths';
 
+// All the languages supported by CodeQL
+const ALL_LANGUAGES = ['csharp', 'cpp', 'go', 'java', 'javascript', 'python'] as const;
+type Language = (typeof ALL_LANGUAGES)[number];
+
+// Some alternate names for languages
+const LANGUAGE_ALIASES: {[name: string]: Language} = {
+  'c': 'cpp',
+  'typescript': 'javascript',
+};
+
 /**
  * Format of the config file supplied by the user.
  */
@@ -38,7 +48,7 @@ export interface Config {
   /**
    * Set of languages to run analysis for.
    */
-  languages: string[];
+  languages: Language[];
   /**
    * Map from language to query files.
    * Will only contain .ql files and not other kinds of files,
@@ -405,9 +415,9 @@ function getConfigFilePropertyError(configFile: string, property: string, error:
 /**
  * Gets the set of languages in the current repository
  */
-async function getLanguagesInRepo(): Promise<string[]> {
+async function getLanguagesInRepo(): Promise<Language[]> {
   // Translate between GitHub's API names for languages and ours
-  const codeqlLanguages = {
+  const codeqlLanguages: {[lang: string]: Language} = {
     'C': 'cpp',
     'C++': 'cpp',
     'C#': 'csharp',
@@ -434,7 +444,7 @@ async function getLanguagesInRepo(): Promise<string[]> {
     // When we pick a language to autobuild we want to pick the most popular traced language
     // Since sets in javascript maintain insertion order, using a set here and then splatting it
     // into an array gives us an array of languages ordered by popularity
-    let languages: Set<string> = new Set();
+    let languages: Set<Language> = new Set();
     for (let lang in response.data) {
       if (lang in codeqlLanguages) {
         languages.add(codeqlLanguages[lang]);
@@ -456,7 +466,7 @@ async function getLanguagesInRepo(): Promise<string[]> {
  * If no languages could be detected from either the workflow or the repository
  * then throw an error.
  */
-async function getLanguages(): Promise<string[]> {
+async function getLanguages(): Promise<Language[]> {
 
   // Obtain from action input 'languages' if set
   let languages = core.getInput('languages', { required: false })
@@ -478,7 +488,29 @@ async function getLanguages(): Promise<string[]> {
         "Please update input in workflow or check that GitHub detects the correct languages in your repository.");
   }
 
-  return languages;
+  // Make sure they are supported
+  const checkedLanguages: Language[] = [];
+  const unknownLanguages: string[] = [];
+  for (let language of languages) {
+    // Normalise to lower case
+    language = language.toLowerCase();
+    // Resolve any known aliases
+    if (language in LANGUAGE_ALIASES) {
+      language = LANGUAGE_ALIASES[language];
+    }
+
+    const checkedLanguage = ALL_LANGUAGES.find(l => l === language);
+    if (checkedLanguage === undefined) {
+      unknownLanguages.push(language);
+    } else if (checkedLanguages.indexOf(checkedLanguage) === -1) {
+      checkedLanguages.push(checkedLanguage);
+    }
+  }
+  if (unknownLanguages.length > 0) {
+    throw new Error("Did not recognise the following languages: " + unknownLanguages.join(', '));
+  }
+
+  return checkedLanguages;
 }
 
 /**