Define CommandLineError and a few exceptions derived from it

solc/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(libsolcli_sources
 	CommandLineInterface.cpp CommandLineInterface.h
 	CommandLineParser.cpp CommandLineParser.h
+	Exceptions.h
 )
 
 add_library(solcli ${libsolcli_sources})

solc/Exceptions.h

@@ -0,0 +1,34 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+/**
+ * Exceptions used by the command-line interface.
+ */
+
+#pragma once
+
+#include <liblangutil/Exceptions.h>
+
+namespace solidity::frontend
+{
+
+struct CommandLineError: virtual util::Exception {};
+struct CommandLineExecutionError: virtual CommandLineError {};
+struct CommandLineValidationError: virtual CommandLineError {};
+struct CommandLineOutputError: virtual CommandLineError {};
+
+}