From 1f087ce15c20ef57d468bb6b94d6e5263aa812cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kamil=20=C5=9Aliwak?= <kamil.sliwak@codepoets.it>
Date: Thu, 23 Sep 2021 16:26:10 +0200
Subject: [PATCH] Define an assertThrow() variant that allows providing the
 default message

---
 libsolutil/Assertions.h | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/libsolutil/Assertions.h b/libsolutil/Assertions.h
index b143e6ed7..815a76290 100644
--- a/libsolutil/Assertions.h
+++ b/libsolutil/Assertions.h
@@ -27,6 +27,8 @@
 
 #include <libsolutil/Exceptions.h>
 
+#include <string>
+
 namespace solidity::util
 {
 
@@ -38,16 +40,32 @@ namespace solidity::util
 #define ETH_FUNC __func__
 #endif
 
-/// Assertion that throws an exception containing the given description if it is not met.
-/// Use it as assertThrow(1 == 1, ExceptionType, "Mathematics is wrong.");
-/// Do NOT supply an exception object as the second parameter.
-#define assertThrow(_condition, _exceptionType, _description) \
+namespace assertions
+{
+
+inline std::string stringOrDefault(std::string _string, std::string _defaultString)
+{
+	// NOTE: Putting this in a function rather than directly in a macro prevents the string from
+	// being evaluated multiple times if it's not just a literal.
+	return (!_string.empty() ? _string : _defaultString);
+}
+
+}
+
+/// Base macro that can be used to implement assertion macros.
+/// Throws an exception containing the given description if the condition is not met.
+/// Allows you to provide the default description for the case where the user of your macro does
+/// not provide any.
+/// The second parameter must be an exception class (rather than an instance).
+#define assertThrowWithDefaultDescription(_condition, _exceptionType, _description, _defaultDescription) \
 	do \
 	{ \
 		if (!(_condition)) \
 			::boost::throw_exception( \
 				_exceptionType() << \
-				::solidity::util::errinfo_comment(_description) << \
+				::solidity::util::errinfo_comment( \
+					::solidity::util::assertions::stringOrDefault(_description, _defaultDescription) \
+				) << \
 				::boost::throw_function(ETH_FUNC) << \
 				::boost::throw_file(__FILE__) << \
 				::boost::throw_line(__LINE__) \
@@ -55,4 +73,10 @@ namespace solidity::util
 	} \
 	while (false)
 
+/// Assertion that throws an exception containing the given description if it is not met.
+/// Use it as assertThrow(1 == 1, ExceptionType, "Mathematics is wrong.");
+/// The second parameter must be an exception class (rather than an instance).
+#define assertThrow(_condition, _exceptionType, _description) \
+	assertThrowWithDefaultDescription(_condition, _exceptionType, _description, "")
+
 }