Fixed MSVC issues with variadic macros

src/mpack/mpack-platform.h

@@ -199,15 +199,24 @@ MPACK_HEADER_START
 #define MPACK_STRINGIFY_IMPL(arg) #arg
 #define MPACK_STRINGIFY(arg) MPACK_STRINGIFY_IMPL(arg)
 
+// This is a workaround for MSVC's incorrect expansion of __VA_ARGS__. It
+// treats __VA_ARGS__ as a single preprocessor token when passed in the
+// argument list of another macro unless we use an outer wrapper to expand it
+// lexically first. (For safety/consistency we use this in all variadic macros
+// that don't ignore the variadic arguments regardless of whether __VA_ARGS__
+// is passed to another macro.)
+//     https://stackoverflow.com/a/32400131
+#define MPACK_EXPAND(x) x
+
 // Extracts the first argument of a variadic macro list, where there might only
 // be one argument.
 #define MPACK_EXTRACT_ARG0_IMPL(first, ...) first
-#define MPACK_EXTRACT_ARG0(...) MPACK_EXTRACT_ARG0_IMPL( __VA_ARGS__ , ignored)
+#define MPACK_EXTRACT_ARG0(...) MPACK_EXPAND(MPACK_EXTRACT_ARG0_IMPL( __VA_ARGS__ , ignored))
 
 // Stringifies the first argument of a variadic macro list, where there might
 // only be one argument.
 #define MPACK_STRINGIFY_ARG0_impl(first, ...) #first
-#define MPACK_STRINGIFY_ARG0(...) MPACK_STRINGIFY_ARG0_impl( __VA_ARGS__ , ignored)
+#define MPACK_STRINGIFY_ARG0(...) MPACK_EXPAND(MPACK_STRINGIFY_ARG0_impl( __VA_ARGS__ , ignored))
 
 
 
@@ -648,14 +657,14 @@ MPACK_HEADER_START
     #if MPACK_STDIO
         MPACK_NORETURN(void mpack_assert_fail_format(const char* format, ...));
         #define mpack_assert_fail_at(line, file, exprstr, format, ...) \
-                mpack_assert_fail_format("mpack assertion failed at " file ":" #line "\n%s\n" format, exprstr, __VA_ARGS__)
+                MPACK_EXPAND(mpack_assert_fail_format("mpack assertion failed at " file ":" #line "\n%s\n" format, exprstr, __VA_ARGS__))
     #else
         #define mpack_assert_fail_at(line, file, exprstr, format, ...) \
                 mpack_assert_fail_wrapper("mpack assertion failed at " file ":" #line "\n" exprstr "\n")
     #endif
 
     #define mpack_assert_fail_pos(line, file, exprstr, expr, ...) \
-            mpack_assert_fail_at(line, file, exprstr, __VA_ARGS__)
+            MPACK_EXPAND(mpack_assert_fail_at(line, file, exprstr, __VA_ARGS__))
 
     // This contains a workaround to the pedantic C99 requirement of having at
     // least one argument to a variadic macro. The first argument is the
@@ -671,26 +680,26 @@ MPACK_HEADER_START
     // -Wformat and __attribute__((format)) on mpack_assert_fail_format() if we
     // ever bothered to implement it.
     #define mpack_assert(...) \
-            ((!(MPACK_EXTRACT_ARG0(__VA_ARGS__))) ? \
+            MPACK_EXPAND(((!(MPACK_EXTRACT_ARG0(__VA_ARGS__))) ? \
                 mpack_assert_fail_pos(__LINE__, __FILE__, MPACK_STRINGIFY_ARG0(__VA_ARGS__) , __VA_ARGS__ , "", NULL) : \
-                (void)0)
+                (void)0))
 
     void mpack_break_hit(const char* message);
     #if MPACK_STDIO
         void mpack_break_hit_format(const char* format, ...);
         #define mpack_break_hit_at(line, file, ...) \
-                mpack_break_hit_format("mpack breakpoint hit at " file ":" #line "\n" __VA_ARGS__)
+                MPACK_EXPAND(mpack_break_hit_format("mpack breakpoint hit at " file ":" #line "\n" __VA_ARGS__))
     #else
         #define mpack_break_hit_at(line, file, ...) \
                 mpack_break_hit("mpack breakpoint hit at " file ":" #line )
     #endif
-    #define mpack_break_hit_pos(line, file, ...) mpack_break_hit_at(line, file, __VA_ARGS__)
-    #define mpack_break(...) mpack_break_hit_pos(__LINE__, __FILE__, __VA_ARGS__)
+    #define mpack_break_hit_pos(line, file, ...) MPACK_EXPAND(mpack_break_hit_at(line, file, __VA_ARGS__))
+    #define mpack_break(...) MPACK_EXPAND(mpack_break_hit_pos(__LINE__, __FILE__, __VA_ARGS__))
 #else
     #define mpack_assert(...) \
-            ((!(MPACK_EXTRACT_ARG0(__VA_ARGS__))) ? \
+            (MPACK_EXPAND((!(MPACK_EXTRACT_ARG0(__VA_ARGS__))) ? \
                 (MPACK_UNREACHABLE, (void)0) : \
-                (void)0)
+                (void)0))
     #define mpack_break(...) ((void)0)
 #endif
 
@@ -780,7 +789,7 @@ size_t mpack_strlen(const char* s);
 /* Debug logging */
 #if 0
     #include <stdio.h>
-    #define mpack_log(...) (printf(__VA_ARGS__), fflush(stdout))
+    #define mpack_log(...) (MPACK_EXPAND(printf(__VA_ARGS__), fflush(stdout)))
 #else
     #define mpack_log(...) ((void)0)
 #endif

src/mpack/mpack-writer.c

@@ -742,7 +742,7 @@ MPACK_STATIC_INLINE void mpack_encode_timestamp_12(char* p, int64_t seconds, uin
 // it will flag an error so we don't have to do anything.
 #define MPACK_WRITE_ENCODED(encode_fn, size, ...) do {                                                 \
     if (MPACK_LIKELY(mpack_writer_buffer_left(writer) >= size) || mpack_writer_ensure(writer, size)) { \
-        encode_fn(writer->current, __VA_ARGS__);                                                       \
+        MPACK_EXPAND(encode_fn(writer->current, __VA_ARGS__));                                         \
         writer->current += size;                                                                       \
     }                                                                                                  \
 } while (0)

test/test.h

@@ -92,10 +92,10 @@ extern "C" {
 // runs the given expression, causing a unit test failure with the
 // given printf format string if the expression is not true.
 #define TEST_TRUE(...) \
-    TEST_TRUE_IMPL((MPACK_EXTRACT_ARG0(__VA_ARGS__)), __FILE__, __LINE__, __VA_ARGS__ , "" , NULL)
+    MPACK_EXPAND(TEST_TRUE_IMPL((MPACK_EXTRACT_ARG0(__VA_ARGS__)), __FILE__, __LINE__, __VA_ARGS__ , "" , NULL))
 
 #define TEST_TRUE_IMPL(result, file, line, ignored, ...) \
-    test_true_impl(result, file, line, __VA_ARGS__)
+    MPACK_EXPAND(test_true_impl(result, file, line, __VA_ARGS__))
 
 void test_true_impl(bool result, const char* file, int line, const char* format, ...);