Use type_traits to test if copyable/assignable

Replace compile tests that check if types are copy constructible and copy assignable with normal tests that use type_traits (if available).

test/compile-test/CMakeLists.txt

@@ -22,14 +22,6 @@ function (expect_compile_error code)
   endif ()
 endfunction ()
 
-# Array is noncopyable.
-expect_compile_error("fmt::internal::Array<char, 5> a, b(a);")
-expect_compile_error("fmt::internal::Array<char, 5> a, b; b = a;")
-
-# Writer is noncopyable.
-expect_compile_error("const fmt::Writer a, b(a);")
-expect_compile_error("fmt::Writer a, b; b = a;")
-
 # MakeArg doesn't accept [const] volatile char *.
 expect_compile_error("volatile char s[] = \"test\"; (fmt::internal::MakeArg<char>)(s);")
 expect_compile_error("const volatile char s[] = \"test\"; (fmt::internal::MakeArg<char>)(s);")

test/format-test.cc

@@ -36,6 +36,10 @@
 #include <sstream>
 #include <stdint.h>
 
+#if FMT_USE_TYPE_TRAITS
+# include <type_traits>
+#endif
+
 #include "gmock/gmock.h"
 
 #include "format.h"
@@ -124,6 +128,16 @@ class TestString {
   }
 };
 
+#if FMT_USE_TYPE_TRAITS
+TEST(WriterTest, NotCopyConstructible) {
+  EXPECT_FALSE(std::is_copy_constructible<BasicWriter<char> >::value);
+}
+
+TEST(WriterTest, NotCopyAssignable) {
+  EXPECT_FALSE(std::is_copy_assignable<BasicWriter<char> >::value);
+}
+#endif
+
 TEST(WriterTest, Ctor) {
   MemoryWriter w;
   EXPECT_EQ(0u, w.size());