tinyformat: Add compile-time checking for literal format strings

ryanofsky · MarcoFalke · ryanofsky · commit e6086e00e32e · 2024-10-28T19:13:46.000-04:00
Co-authored-by: MarcoFalke &lt;*~=`'#}+{/-|&amp;$^_@721217.xyz&gt;
diff --git a/src/tinyformat.h b/src/tinyformat.h
@@ -145,6 +145,7 @@ namespace tfm = tinyformat;
 #include <iostream>
 #include <sstream>
 #include <stdexcept> // Added for Bitcoin Core
+#include <util/string.h> // Added for Bitcoin Core
 
 #ifndef TINYFORMAT_ASSERT
 #   include <cassert>
@@ -178,6 +179,18 @@ namespace tfm = tinyformat;
 
 namespace tinyformat {
 
+// Added for Bitcoin Core. Wrapper for checking format strings at compile time.
+// Unlike ConstevalFormatString this supports std::string for runtime string
+// formatting without compile time checks.
+template <unsigned num_params>
+struct FormatStringCheck {
+    consteval FormatStringCheck(const char* str) : fmt{util::ConstevalFormatString<num_params>{str}.fmt} {}
+    FormatStringCheck(const std::string& str) : fmt{str.c_str()} {}
+    FormatStringCheck(util::ConstevalFormatString<num_params> str) : fmt{str.fmt} {}
+    operator const char*() { return fmt; }
+    const char* fmt;
+};
+
 // Added for Bitcoin Core
 class format_error: public std::runtime_error
 {
@@ -1056,15 +1069,15 @@ inline void vformat(std::ostream& out, const char* fmt, FormatListRef list)
 
 /// Format list of arguments to the stream according to given format string.
 template<typename... Args>
-void format(std::ostream& out, const char* fmt, const Args&... args)
+void format(std::ostream& out, FormatStringCheck<sizeof...(Args)> fmt, const Args&... args)
 {
     vformat(out, fmt, makeFormatList(args...));
 }
 
 /// Format list of arguments according to the given format string and return
 /// the result as a string.
 template<typename... Args>
-std::string format(const char* fmt, const Args&... args)
+std::string format(FormatStringCheck<sizeof...(Args)> fmt, const Args&... args)
 {
     std::ostringstream oss;
     format(oss, fmt, args...);
@@ -1145,15 +1158,6 @@ TINYFORMAT_FOREACH_ARGNUM(TINYFORMAT_MAKE_FORMAT_FUNCS)
 
 #endif
 
-// Added for Bitcoin Core
-template<typename... Args>
-std::string format(const std::string &fmt, const Args&... args)
-{
-    std::ostringstream oss;
-    format(oss, fmt.c_str(), args...);
-    return oss.str();
-}
-
 } // namespace tinyformat
 
 // Added for Bitcoin Core:
diff --git a/src/util/string.h b/src/util/string.h
@@ -6,7 +6,6 @@
 #define BITCOIN_UTIL_STRING_H
 
 #include <span.h>
-#include <tinyformat.h>
 
 #include <array>
 #include <cstdint>
@@ -258,12 +257,4 @@ template <typename T1, size_t PREFIX_LEN>
 }
 } // namespace util
 
-namespace tinyformat {
-template <typename... Args>
-std::string format(util::ConstevalFormatString<sizeof...(Args)> fmt, const Args&... args)
-{
-    return format(fmt.fmt, args...);
-}
-} // namespace tinyformat
-
 #endif // BITCOIN_UTIL_STRING_H
