Optimize str_format(…, …, "%d", …) using templates

This would make the function `str_from_int` unnecessary, at least
user-facing.

Advantage: User doesn't have to care about `str_from_int`/`str_format`
distinction.

Disadvantage: We're adding some template programming to `system.h`,
potentially slowing all compilation.

CMakeLists.txt

@@ -319,7 +319,11 @@ if(NOT MSVC AND NOT HAIKU)
   add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wno-psabi) # parameter passing for argument of type ‘__gnu_cxx::__normal_iterator<CCommandProcessorFragment_Vulkan::SMemoryBlock<1>*, std::vector<CCommandProcessorFragment_Vulkan::SMemoryBlock<1>, std::allocator<CCommandProcessorFragment_Vulkan::SMemoryBlock<1> > > >’ changed in GCC 7.1
   add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wno-unused-parameter)
   add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wno-missing-field-initializers)
+  if(CMAKE_BUILD_TYPE STREQUAL DEBUG)
     add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wformat=2) # Warn about format strings.
+  else()
+    add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wno-format) # Don't warn about format strings in release mode since our `str_format` optimization is incompatible with it.
+  endif()
   add_c_compiler_flag_if_supported(OUR_FLAGS_DEP -Wno-implicit-function-declaration)
   add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wno-nullability-completeness) # Mac OS build on github
   add_cxx_compiler_flag_if_supported(OUR_FLAGS_OWN -Wduplicated-cond)

src/base/system.cpp

@@ -2784,6 +2784,15 @@ int str_format_v(char *buffer, int buffer_size, const char *format, va_list args
 	return str_utf8_fix_truncation(buffer);
 }
 
+int str_format_int(char *buffer, size_t buffer_size, int value)
+{
+	buffer[0] = '\0'; // Fix false positive clang-analyzer-core.UndefinedBinaryOperatorResult when using result
+	auto result = std::to_chars(buffer, buffer + buffer_size - 1, value);
+	result.ptr[0] = '\0';
+	return result.ptr - buffer;
+}
+
+#undef str_format
 int str_format(char *buffer, int buffer_size, const char *format, ...)
 {
 	va_list args;
@@ -2792,6 +2801,9 @@ int str_format(char *buffer, int buffer_size, const char *format, ...)
 	va_end(args);
 	return length;
 }
+#if !defined(CONF_DEBUG)
+#define str_format str_format_opt
+#endif
 
 const char *str_trim_words(const char *str, int words)
 {
@@ -3639,13 +3651,6 @@ bool str_tofloat(const char *str, float *out)
 	return true;
 }
 
-void str_from_int(int value, char *buffer, size_t buffer_size)
-{
-	buffer[0] = '\0'; // Fix false positive clang-analyzer-core.UndefinedBinaryOperatorResult when using result
-	auto result = std::to_chars(buffer, buffer + buffer_size - 1, value);
-	result.ptr[0] = '\0';
-}
-
 int str_utf8_comp_nocase(const char *a, const char *b)
 {
 	int code_a;

src/base/system.h

@@ -1229,6 +1229,31 @@ int str_format_v(char *buffer, int buffer_size, const char *format, va_list args
 int str_format(char *buffer, int buffer_size, const char *format, ...)
 	GNUC_ATTRIBUTE((format(printf, 3, 4)));
 
+#if !defined(CONF_DEBUG)
+int str_format_int(char *buffer, size_t buffer_size, int value);
+
+template<typename... Args>
+int str_format_opt(char *buffer, int buffer_size, const char *format, Args... args)
+{
+	return str_format(buffer, buffer_size, format, args...);
+}
+
+template<>
+inline int str_format_opt(char *buffer, int buffer_size, const char *format, int val)
+{
+	if(strcmp(format, "%d") == 0)
+	{
+		return str_format_int(buffer, buffer_size, val);
+	}
+	else
+	{
+		return str_format(buffer, buffer_size, format, val);
+	}
+}
+
+#define str_format str_format_opt
+#endif
+
 /**
  * Trims specific number of words at the start of a string.
  *
@@ -2098,14 +2123,6 @@ int64_t str_toint64_base(const char *str, int base = 10);
 float str_tofloat(const char *str);
 bool str_tofloat(const char *str, float *out);
 
-void str_from_int(int value, char *buffer, size_t buffer_size);
-
-template<size_t N>
-void str_from_int(int value, char (&dst)[N])
-{
-	str_from_int(value, dst, N);
-}
-
 /**
  * Determines whether a character is whitespace.
  *