Allow compiling and using as DLL in windows (#502)

* fix warnings and errors in test compiles with BUILD_SHARED_LIBS

* did requested changes and added one change to allow all tests to succeed
in windows DLL

(cherry picked from commit 79f11dbaa7)

fmt/format.h

@@ -699,7 +699,8 @@ class Buffer {
 template <typename T>
 template <typename U>
 void Buffer<T>::append(const U *begin, const U *end) {
-  std::size_t new_size = size_ + internal::to_unsigned(end - begin);
+  FMT_ASSERT(end >= begin, "negative value");
+  std::size_t new_size = size_ + (end - begin);
   if (new_size > capacity_)
     grow(new_size);
   std::uninitialized_copy(begin, end,

fmt/posix.h

@@ -110,7 +110,7 @@ class BufferedFile {
   BufferedFile() FMT_NOEXCEPT : file_(FMT_NULL) {}
 
   // Destroys the object closing the file it represents if any.
-  ~BufferedFile() FMT_NOEXCEPT;
+  FMT_API ~BufferedFile() FMT_NOEXCEPT;
 
 #if !FMT_USE_RVALUE_REFERENCES
   // Emulate a move constructor and a move assignment operator if rvalue
@@ -173,17 +173,17 @@ public:
 #endif
 
   // Opens a file.
-  BufferedFile(CStringRef filename, CStringRef mode);
+  FMT_API BufferedFile(CStringRef filename, CStringRef mode);
 
   // Closes the file.
-  void close();
+  FMT_API void close();
 
   // Returns the pointer to a FILE object representing this file.
   FILE *get() const FMT_NOEXCEPT { return file_; }
 
   // We place parentheses around fileno to workaround a bug in some versions
   // of MinGW that define fileno as a macro.
-  int (fileno)() const;
+  FMT_API int (fileno)() const;
 
   void print(CStringRef format_str, const ArgList &args) {
     fmt::print(file_, format_str, args);
@@ -216,7 +216,7 @@ class File {
   File() FMT_NOEXCEPT : fd_(-1) {}
 
   // Opens a file and constructs a File object representing this file.
-  File(CStringRef path, int oflag);
+  FMT_API File(CStringRef path, int oflag);
 
 #if !FMT_USE_RVALUE_REFERENCES
   // Emulate a move constructor and a move assignment operator if rvalue
@@ -279,43 +279,43 @@ class File {
 #endif
 
   // Destroys the object closing the file it represents if any.
-  ~File() FMT_NOEXCEPT;
+  FMT_API ~File() FMT_NOEXCEPT;
 
   // Returns the file descriptor.
   int descriptor() const FMT_NOEXCEPT { return fd_; }
 
   // Closes the file.
-  void close();
+  FMT_API void close();
 
   // Returns the file size. The size has signed type for consistency with
   // stat::st_size.
-  LongLong size() const;
+  FMT_API LongLong size() const;
 
   // Attempts to read count bytes from the file into the specified buffer.
-  std::size_t read(void *buffer, std::size_t count);
+  FMT_API std::size_t read(void *buffer, std::size_t count);
 
   // Attempts to write count bytes from the specified buffer to the file.
-  std::size_t write(const void *buffer, std::size_t count);
+  FMT_API std::size_t write(const void *buffer, std::size_t count);
 
   // Duplicates a file descriptor with the dup function and returns
   // the duplicate as a file object.
-  static File dup(int fd);
+  FMT_API static File dup(int fd);
 
   // Makes fd be the copy of this file descriptor, closing fd first if
   // necessary.
-  void dup2(int fd);
+  FMT_API void dup2(int fd);
 
   // Makes fd be the copy of this file descriptor, closing fd first if
   // necessary.
-  void dup2(int fd, ErrorCode &ec) FMT_NOEXCEPT;
+  FMT_API void dup2(int fd, ErrorCode &ec) FMT_NOEXCEPT;
 
   // Creates a pipe setting up read_end and write_end file objects for reading
   // and writing respectively.
-  static void pipe(File &read_end, File &write_end);
+  FMT_API static void pipe(File &read_end, File &write_end);
 
   // Creates a BufferedFile object associated with this file and detaches
   // this File object from the file.
-  BufferedFile fdopen(const char *mode);
+  FMT_API BufferedFile fdopen(const char *mode);
 };
 
 // Returns the memory page size.

test/format-impl-test.cc

@@ -26,6 +26,7 @@
  */
 
 #define FMT_NOEXCEPT
+#undef FMT_SHARED
 #include "test-assert.h"
 
 // Include format.cc instead of format.h to test implementation-specific stuff.

test/time-test.cc

@@ -6,6 +6,9 @@
 
  For the license information refer to format.h.
  */
+#ifdef WIN32
+#define _CRT_SECURE_NO_WARNINGS
+#endif
 
 #include "gmock/gmock.h"
 #include "fmt/time.h"