From 9aafa32825f17f6e66c0fd6f6747c28b1402069f Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Fri, 25 Jan 2019 01:59:42 +0000
Subject: [PATCH] Disallow empty import statements

---
 Changelog.md                                          | 2 +-
 libsolidity/interface/CompilerStack.cpp               | 2 ++
 libsolidity/parsing/Parser.cpp                        | 2 ++
 test/libsolidity/syntaxTests/parsing/import_empty.sol | 3 +++
 4 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 test/libsolidity/syntaxTests/parsing/import_empty.sol

diff --git a/Changelog.md b/Changelog.md
index bc41fb810..ff635c208 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,10 +1,10 @@
 ### 0.5.4 (unreleased)
 
 Bugfixes:
+ * Parser: Disallow empty import statements.
  * Type system: Properly report packed encoded size for arrays and structs (mostly unused until now).
 
 
-
 Language Features:
 
 
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 9e4da62d8..0c140887c 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -681,6 +681,8 @@ StringMap CompilerStack::loadMissingSources(SourceUnit const& _ast, std::string
 	for (auto const& node: _ast.nodes())
 		if (ImportDirective const* import = dynamic_cast<ImportDirective*>(node.get()))
 		{
+			solAssert(!import->path().empty(), "Import path cannot be empty.");
+
 			string importPath = dev::absolutePath(import->path(), _sourcePath);
 			// The current value of `path` is the absolute path as seen from this source file.
 			// We first have to apply remappings before we can store the actual absolute path
diff --git a/libsolidity/parsing/Parser.cpp b/libsolidity/parsing/Parser.cpp
index 35476a76f..8cbac5a29 100644
--- a/libsolidity/parsing/Parser.cpp
+++ b/libsolidity/parsing/Parser.cpp
@@ -221,6 +221,8 @@ ASTPointer<ImportDirective> Parser::parseImportDirective()
 			fatalParserError("Expected import path.");
 		path = getLiteralAndAdvance();
 	}
+	if (path->empty())
+		fatalParserError("Import path cannot be empty.");
 	nodeFactory.markEndPosition();
 	expectToken(Token::Semicolon);
 	return nodeFactory.createNode<ImportDirective>(path, unitAlias, move(symbolAliases));
diff --git a/test/libsolidity/syntaxTests/parsing/import_empty.sol b/test/libsolidity/syntaxTests/parsing/import_empty.sol
new file mode 100644
index 000000000..1853f6ec3
--- /dev/null
+++ b/test/libsolidity/syntaxTests/parsing/import_empty.sol
@@ -0,0 +1,3 @@
+import "";
+// ----
+// ParserError: (9-10): Import path cannot be empty.