Allow formatting of volatile variables. (#62)

Author: c42f

tinyformat.h

@@ -506,7 +506,9 @@ class FormatArg
 
         template<typename T>
         FormatArg(const T& value)
-            : m_value(static_cast<const void*>(&value)),
+            // C-style cast here allows us to also remove volatile; we put it
+            // back in the *Impl functions before dereferencing to avoid UB.
+            : m_value((const void*)(&value)),
             m_formatImpl(&formatImpl<T>),
             m_toIntImpl(&toIntImpl<T>)
         { }

tinyformat_test.cpp

@@ -286,6 +286,9 @@ int unitTests()
 
     //------------------------------------------------------------
     // Misc
+    volatile int i = 1234;
+    CHECK_EQUAL(tfm::format("%d", i), "1234");
+
 #ifdef TEST_WCHAR_T_COMPILE
     // Test wchar_t handling - should fail to compile!
     tfm::format("%ls", L"blah");