Allow specifying external-sources=true in shellcheckrc (fixes #1818)

src/ShellCheck/Parser.hs

@@ -987,9 +987,9 @@ prop_readAnnotation7 = isOk readAnnotation "# shellcheck disable=SC1000,SC2000-S
 readAnnotation = called "shellcheck directive" $ do
     try readAnnotationPrefix
     many1 linewhitespace
-    readAnnotationWithoutPrefix
+    readAnnotationWithoutPrefix True
 
-readAnnotationWithoutPrefix = do
+readAnnotationWithoutPrefix sandboxed = do
     values <- many1 readKey
     optional readAnyComment
     void linefeed <|> eof <|> do
@@ -1035,6 +1035,21 @@ readAnnotationWithoutPrefix = do
                         "This shell type is unknown. Use e.g. sh or bash."
                 return [ShellOverride shell]
 
+            "external-sources" -> do
+                pos <- getPosition
+                value <- many1 letter
+                case value of
+                    "true" ->
+                        if sandboxed
+                        then do
+                            parseNoteAt pos ErrorC 1144 "external-sources can only be enabled in .shellcheckrc, not in individual files."
+                            return []
+                        else return [ExternalSources True]
+                    "false" -> return [ExternalSources False]
+                    _ -> do
+                        parseNoteAt pos ErrorC 1145 "Unknown external-sources value. Expected true/false."
+                        return []
+
             _ -> do
                 parseNoteAt keyPos WarningC 1107 "This directive is unknown. It will be ignored."
                 anyChar `reluctantlyTill` whitespace
@@ -2176,10 +2191,12 @@ readSource t@(T_Redirecting _ _ (T_SimpleCommand cmdId _ (cmd:file':rest'))) = d
                     if filename == "/dev/null" -- always allow /dev/null
                     then return (Right "", filename)
                     else do
+                        allAnnotations <- getCurrentAnnotations True
                         currentScript <- Mr.asks currentFilename
-                        paths <- mapMaybe getSourcePath <$> getCurrentAnnotations True
-                        resolved <- system $ siFindSource sys currentScript paths filename
-                        contents <- system $ siReadFile sys resolved
+                        let paths = mapMaybe getSourcePath allAnnotations
+                        let externalSources = listToMaybe $ mapMaybe getExternalSources allAnnotations
+                        resolved <- system $ siFindSource sys currentScript externalSources paths filename
+                        contents <- system $ siReadFile sys externalSources resolved
                         return (contents, resolved)
                 case input of
                     Left err -> do
@@ -2213,6 +2230,11 @@ readSource t@(T_Redirecting _ _ (T_SimpleCommand cmdId _ (cmd:file':rest'))) = d
             SourcePath x -> Just x
             _ -> Nothing
 
+    getExternalSources t =
+        case t of
+            ExternalSources b -> Just b
+            _ -> Nothing
+
     -- If the word has a single expansion as the directory, try stripping it
     -- This affects `$foo/bar` but not `${foo}-dir/bar` or `/foo/$file`
     stripDynamicPrefix word =
@@ -3202,7 +3224,7 @@ prop_readConfigKVs4 = isOk readConfigKVs "\n\n\n\n\t \n"
 prop_readConfigKVs5 = isOk readConfigKVs "# shellcheck accepts annotation-like comments in rc files\ndisable=1234"
 readConfigKVs = do
     anySpacingOrComment
-    annotations <- many (readAnnotationWithoutPrefix <* anySpacingOrComment)
+    annotations <- many (readAnnotationWithoutPrefix False <* anySpacingOrComment)
     eof
     return $ concat annotations
 anySpacingOrComment =