update statement completion for fasta scanner

pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart

Index: pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart b/pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart
index 1a6945a65b9cbdd2c7e6630e68090282c2e89db2..44754d63e85b7a43f0ff3e4cfce667ffa25c851e 100644
--- a/pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart
+++ b/pkg/analysis_server/lib/src/services/completion/statement/statement_completion.dart
@@ -329,6 +329,10 @@ class StatementCompletionProcessor {
       _addInsertEdit(loc, delimiter);
     }
     expr = errorMatching(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "']'");
+    if (expr == null) {

[Brian Wilkerson, 2017/06/14 04:14:31]

You could also use `??` to avoid the extra weight of an `if` statement.

[danrubel, 2017/06/14 06:05:41]

Good point. Done.

+      expr =
+          errorMatching(ScannerErrorCode.EXPECTED_TOKEN, partialMatch: "']'");
+    }
     if (expr != null) {
       expr = expr.getAncestor((n) => n is ListLiteral);
       if (expr != null) {
@@ -343,6 +347,7 @@ class StatementCompletionProcessor {
             _addInsertEdit(loc, ']');
           }
           _removeError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "']'");
+          _removeError(ScannerErrorCode.EXPECTED_TOKEN, partialMatch: "']'");
           var ms =
               _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
           if (ms != null) {
@@ -425,7 +430,10 @@ class StatementCompletionProcessor {
           _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "';'");
       if (error != null) {
         int insertOffset;
-        if (expr == null || expr.isSynthetic) {
+        // Fasta scanner reports unterminated string literal errors
+        // and generates a synthetic string token with non-zero length.
+        // Because of this, check for length == 0 rather than isSynthetic.

[Brian Wilkerson, 2017/06/14 04:14:31]

If `isSynthetic` doesn't always return a valid result, then can we either (a)
fix it so that it does (my preference), or (b) remove / deprecate it so that
people won't use it incorrectly?

+        if (expr == null || expr.length == 0) {
           if (node is ReturnStatement) {
             insertOffset = (node as ReturnStatement).returnKeyword.end;
           } else if (node is ExpressionStatement) {
@@ -829,6 +837,10 @@ class StatementCompletionProcessor {
   bool _complete_methodCall() {
     var parenError =
         _findError(ParserErrorCode.EXPECTED_TOKEN, partialMatch: "')'");
+    if (parenError == null) {
+      parenError =
+          _findError(ScannerErrorCode.EXPECTED_TOKEN, partialMatch: "')'");
+    }
     if (parenError == null) {
       return false;
     }