From a0ebdbc089aa9a1c88077abc37e62c74ac30160b Mon Sep 17 00:00:00 2001
From: Rintaro Ishizaki <rishizaki@apple.com>
Date: Sat, 22 Sep 2018 02:09:19 +0900
Subject: [PATCH] [Lexer] Fix assertion failure for unterminated string literal

in string interpolation in multiline string literal.

    """
    \("<-this is unterminated.
    """

In this case, the outer multiline literal should form 'tok::unknown'
along with a error message.
---
 lib/Parse/Lexer.cpp                  | 6 ++++++
 test/Parse/multiline_errors.swift    | 7 +++++++
 test/Parse/string_literal_eof4.swift | 6 ++++++
 test/Parse/string_literal_eof5.swift | 7 +++++++
 test/Parse/string_literal_eof6.swift | 7 +++++++
 test/Parse/string_literal_eof7.swift | 9 +++++++++
 6 files changed, 42 insertions(+)
 create mode 100644 test/Parse/string_literal_eof4.swift
 create mode 100644 test/Parse/string_literal_eof5.swift
 create mode 100644 test/Parse/string_literal_eof6.swift
 create mode 100644 test/Parse/string_literal_eof7.swift

diff --git a/lib/Parse/Lexer.cpp b/lib/Parse/Lexer.cpp
index b614aa01c5c6e..c09b28847d363 100644
--- a/lib/Parse/Lexer.cpp
+++ b/lib/Parse/Lexer.cpp
@@ -1817,6 +1817,12 @@ void Lexer::lexStringLiteral(unsigned CustomDelimiterLen) {
         // Successfully scanned the body of the expression literal.
         ++CurPtr;
         continue;
+      } else if ((*CurPtr == '\r' || *CurPtr == '\n') && IsMultilineString) {
+        // The only case we reach here is unterminated single line string in the
+        // interpolation. For better recovery, go on after emitting an error.
+        diagnose(CurPtr, diag::lex_unterminated_string);
+        wasErroneous = true;
+        continue;
       }
 
       // Being diagnosed below.
diff --git a/test/Parse/multiline_errors.swift b/test/Parse/multiline_errors.swift
index 4fa56d09cc8d3..de5c3cdaaa38c 100644
--- a/test/Parse/multiline_errors.swift
+++ b/test/Parse/multiline_errors.swift
@@ -184,3 +184,10 @@ _ = """\
   // FIXME: Bad diagnostics
   // expected-error@-3 {{multi-line string literal content must begin on a new line}}
   // expected-error@-4 {{escaped newline at the last line is not allowed}} {{8-9=}}
+
+let _ = """
+  foo
+  \("bar
+  baz
+  """
+  // expected-error@-3 {{unterminated string literal}}
diff --git a/test/Parse/string_literal_eof4.swift b/test/Parse/string_literal_eof4.swift
new file mode 100644
index 0000000000000..2f8f45139ee06
--- /dev/null
+++ b/test/Parse/string_literal_eof4.swift
@@ -0,0 +1,6 @@
+// RUN: %target-typecheck-verify-swift
+
+// NOTE: DO NOT add a newline at EOF.
+// expected-error@+1 {{unterminated string literal}}
+_ = """
+    foo
\ No newline at end of file
diff --git a/test/Parse/string_literal_eof5.swift b/test/Parse/string_literal_eof5.swift
new file mode 100644
index 0000000000000..04c359abab47e
--- /dev/null
+++ b/test/Parse/string_literal_eof5.swift
@@ -0,0 +1,7 @@
+// RUN: %target-typecheck-verify-swift
+
+// NOTE: DO NOT add a newline at EOF.
+// expected-error@+1 {{unterminated string literal}}
+_ = """
+    foo
+    \(
diff --git a/test/Parse/string_literal_eof6.swift b/test/Parse/string_literal_eof6.swift
new file mode 100644
index 0000000000000..43611f4f6ffa9
--- /dev/null
+++ b/test/Parse/string_literal_eof6.swift
@@ -0,0 +1,7 @@
+// RUN: %target-typecheck-verify-swift
+
+// NOTE: DO NOT add a newline at EOF.
+// expected-error@+1 {{unterminated string literal}}
+_ = """
+    foo
+    \("bar
\ No newline at end of file
diff --git a/test/Parse/string_literal_eof7.swift b/test/Parse/string_literal_eof7.swift
new file mode 100644
index 0000000000000..8525270a45c7c
--- /dev/null
+++ b/test/Parse/string_literal_eof7.swift
@@ -0,0 +1,9 @@
+// RUN: %target-typecheck-verify-swift
+
+// expected-error@+4 {{unterminated string literal}}
+// expected-error@+1 {{unterminated string literal}}
+_ = """
+    foo
+    \("bar
+    baz
+