From 840df80dac25cab6ef211a876fa6a44d991aa00e Mon Sep 17 00:00:00 2001
From: Djordje Mijovic <djordje.mijovic@gmail.com>
Date: Tue, 23 Feb 2021 11:05:07 +0100
Subject: [PATCH] Check if all types in bytes.concat are fixed bytes or byte
 array.

---
 libsolidity/analysis/TypeChecker.cpp | 32 ++++++++++++++++++++++++++++
 libsolidity/analysis/TypeChecker.h   |  6 ++++++
 2 files changed, 38 insertions(+)

diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 9cd6cb2f5..c3309600b 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -2027,6 +2027,32 @@ void TypeChecker::typeCheckABIEncodeFunctions(
 	}
 }
 
+void TypeChecker::typeCheckBytesConcatFunction(
+	FunctionCall const& _functionCall,
+	FunctionType const* _functionType
+)
+{
+	solAssert(_functionType, "");
+	solAssert(_functionType->kind() == FunctionType::Kind::BytesConcat, "");
+	solAssert(_functionCall.names().empty(), "");
+
+	typeCheckFunctionGeneralChecks(_functionCall, _functionType);
+
+	for (shared_ptr<Expression const> const& argument: _functionCall.arguments())
+		if (
+			Type const* argumentType = type(*argument);
+			!argumentType->isImplicitlyConvertibleTo(*TypeProvider::fixedBytes(32)) &&
+			!argumentType->isImplicitlyConvertibleTo(*TypeProvider::bytesMemory())
+		)
+			m_errorReporter.typeError(
+				8015_error,
+				argument->location(),
+				"Invalid type for argument in the bytes.concat function call. "
+				"bytes or fixed bytes type is required, but " +
+				argumentType->toString(true) + " provided."
+			);
+}
+
 void TypeChecker::typeCheckFunctionGeneralChecks(
 	FunctionCall const& _functionCall,
 	FunctionTypePointer _functionType
@@ -2433,6 +2459,12 @@ bool TypeChecker::visit(FunctionCall const& _functionCall)
 		case FunctionType::Kind::MetaType:
 			returnTypes = typeCheckMetaTypeFunctionAndRetrieveReturnType(_functionCall);
 			break;
+		case FunctionType::Kind::BytesConcat:
+		{
+			typeCheckBytesConcatFunction(_functionCall, functionType);
+			returnTypes = functionType->returnParameterTypes();
+			break;
+		}
 		default:
 		{
 			typeCheckFunctionCall(_functionCall, functionType);
diff --git a/libsolidity/analysis/TypeChecker.h b/libsolidity/analysis/TypeChecker.h
index e2e1fa2b2..cc8da6f7f 100644
--- a/libsolidity/analysis/TypeChecker.h
+++ b/libsolidity/analysis/TypeChecker.h
@@ -111,6 +111,12 @@ private:
 		FunctionTypePointer _functionType
 	);
 
+	/// Performs general checks and checks specific to bytes concat function call
+	void typeCheckBytesConcatFunction(
+		FunctionCall const& _functionCall,
+		FunctionType const* _functionType
+	);
+
 	void endVisit(InheritanceSpecifier const& _inheritance) override;
 	void endVisit(ModifierDefinition const& _modifier) override;
 	bool visit(FunctionDefinition const& _function) override;