From 356b9a7904759c0763d566b5c8ba7a72707da64e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kamil=20=C5=9Aliwak?= <kamil.sliwak@codepoets.it>
Date: Thu, 2 Jul 2020 14:14:36 +0200
Subject: [PATCH] Restrict `linkersymbol` builtin to object dialect of Yul

---
 libyul/backends/evm/EVMDialect.cpp            | 21 +++++++++----------
 .../inlineAssembly/linkersymbol_builtin.sol   | 10 +++++++++
 .../inlineAssembly/linkersymbol_function.sol  | 10 +++++++++
 3 files changed, 30 insertions(+), 11 deletions(-)
 create mode 100644 test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_builtin.sol
 create mode 100644 test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_function.sol

diff --git a/libyul/backends/evm/EVMDialect.cpp b/libyul/backends/evm/EVMDialect.cpp
index b6a46043e..342c0e6ed 100644
--- a/libyul/backends/evm/EVMDialect.cpp
+++ b/libyul/backends/evm/EVMDialect.cpp
@@ -124,19 +124,18 @@ map<YulString, BuiltinFunctionForEVM> createBuiltins(langutil::EVMVersion _evmVe
 		)
 			builtins.emplace(createEVMFunction(instr.first, instr.second));
 
-	builtins.emplace(createFunction("linkersymbol", 1, 1, SideEffects{}, {true}, [](
-		FunctionCall const& _call,
-		AbstractAssembly& _assembly,
-		BuiltinContext&,
-		function<void(Expression const&)>
-	) {
-		yulAssert(_call.arguments.size() == 1, "");
-		Expression const& arg = _call.arguments.front();
-		_assembly.appendLinkerSymbol(std::get<Literal>(arg).value.str());
-	}));
-
 	if (_objectAccess)
 	{
+		builtins.emplace(createFunction("linkersymbol", 1, 1, SideEffects{}, {true}, [](
+			FunctionCall const& _call,
+			AbstractAssembly& _assembly,
+			BuiltinContext&,
+			function<void(Expression const&)>
+		) {
+			yulAssert(_call.arguments.size() == 1, "");
+			Expression const& arg = _call.arguments.front();
+			_assembly.appendLinkerSymbol(std::get<Literal>(arg).value.str());
+		}));
 		builtins.emplace(createFunction("datasize", 1, 1, SideEffects{}, {true}, [](
 			FunctionCall const& _call,
 			AbstractAssembly& _assembly,
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_builtin.sol b/test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_builtin.sol
new file mode 100644
index 000000000..9f761f187
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_builtin.sol
@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      pop(linkersymbol("contract/library.sol:L"))
+    }
+  }
+}
+// ----
+// DeclarationError 4619: (67-79): Function not found.
+// TypeError 3950: (67-105): Expected expression to evaluate to one value, but got 0 values instead.
diff --git a/test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_function.sol b/test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_function.sol
new file mode 100644
index 000000000..9d1d6c4f3
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_function.sol
@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      function linkersymbol(a) {}
+
+      linkersymbol("contract/library.sol:L")
+    }
+  }
+}
+// ----