Disallow trailing dots that are not followed by a number

6 files changed, 46 insertions, 1 deletions

diff --git a/Changelog.md b/Changelog.md
index 3c4e5a7e..708d1b8a 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -6,6 +6,7 @@ Breaking Changes:
  * Commandline interface: Require ``-`` if standard input is used as source.
  * General: ``continue`` in a ``do...while`` loop jumps to the condition (it used to jump to the loop body). Warning: this may silently change the semantics of existing code.
  * Type Checker: Disallow arithmetic operations for Boolean variables.
+ * Disallow trailing dots that are not followed by a number.
 
 Language Features:
  * General: Allow appending ``calldata`` keyword to types, to explicitly specify data location for arguments of external functions.
diff --git a/libsolidity/parsing/Scanner.cpp b/libsolidity/parsing/Scanner.cpp
index 6541f6c2..801d2cc4 100644
--- a/libsolidity/parsing/Scanner.cpp
+++ b/libsolidity/parsing/Scanner.cpp
@@ -768,8 +768,14 @@ Token::Value Scanner::scanNumber(char _charSeen)
 			scanDecimalDigits();  // optional
 			if (m_char == '.')
 			{
+				// A '.' has to be followed by a number.
+				if (m_source.isPastEndOfInput() || !isDecimalDigit(m_source.get(1)))
+				{
+					literal.complete();
+					return Token::Number;
+				}
 				addLiteralCharAndAdvance();
-				scanDecimalDigits();  // optional
+				scanDecimalDigits();
 			}
 		}
 	}
diff --git a/test/libsolidity/SolidityScanner.cpp b/test/libsolidity/SolidityScanner.cpp
index 020bce7f..f455c5eb 100644
--- a/test/libsolidity/SolidityScanner.cpp
+++ b/test/libsolidity/SolidityScanner.cpp
@@ -127,6 +127,26 @@ BOOST_AUTO_TEST_CASE(scientific_notation)
 	BOOST_CHECK_EQUAL(scanner.next(), Token::EOS);
 }
 
+BOOST_AUTO_TEST_CASE(trailing_dot)
+{
+	Scanner scanner(CharStream("2.5"));
+	BOOST_CHECK_EQUAL(scanner.currentToken(), Token::Number);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::EOS);
+	scanner.reset(CharStream("2.5e10"), "");
+	BOOST_CHECK_EQUAL(scanner.currentToken(), Token::Number);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::EOS);
+	scanner.reset(CharStream(".5"), "");
+	BOOST_CHECK_EQUAL(scanner.currentToken(), Token::Number);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::EOS);
+	scanner.reset(CharStream(".5e10"), "");
+	BOOST_CHECK_EQUAL(scanner.currentToken(), Token::Number);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::EOS);
+	scanner.reset(CharStream("2."), "");
+	BOOST_CHECK_EQUAL(scanner.currentToken(), Token::Number);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::Period);
+	BOOST_CHECK_EQUAL(scanner.next(), Token::EOS);
+}
+
 BOOST_AUTO_TEST_CASE(negative_numbers)
 {
 	Scanner scanner(CharStream("var x = -.2 + -0x78 + -7.3 + 8.9 + 2e-2;"));
diff --git a/test/libsolidity/syntaxTests/parsing/trailing_dot1.sol b/test/libsolidity/syntaxTests/parsing/trailing_dot1.sol
new file mode 100644
index 00000000..7f26242c
--- /dev/null
+++ b/test/libsolidity/syntaxTests/parsing/trailing_dot1.sol
@@ -0,0 +1,7 @@
+contract test {
+	uint256 a = 2.2e10;
+	uint256 b = .5E10;
+	uint256 c = 4.e-2;
+}
+// ----
+// TypeError: (70-73): Member "e" not found or not visible after argument-dependent lookup in int_const 4
diff --git a/test/libsolidity/syntaxTests/parsing/trailing_dot2.sol b/test/libsolidity/syntaxTests/parsing/trailing_dot2.sol
new file mode 100644
index 00000000..38a7ab2d
--- /dev/null
+++ b/test/libsolidity/syntaxTests/parsing/trailing_dot2.sol
@@ -0,0 +1,7 @@
+contract test {
+	uint256 a = 2.2e10;
+	uint256 b = .5E10;
+	uint256 c = 2 + 2.;
+}
+// ----
+// ParserError: (76-77): Expected identifier but got ';'
diff --git a/test/libsolidity/syntaxTests/parsing/trailing_dot3.sol b/test/libsolidity/syntaxTests/parsing/trailing_dot3.sol
new file mode 100644
index 00000000..6a126cb3
--- /dev/null
+++ b/test/libsolidity/syntaxTests/parsing/trailing_dot3.sol
@@ -0,0 +1,4 @@
+contract test {
+	uint a = 2.
+// ----
+// ParserError: (29-29): Expected identifier but got end of source