Merge pull request #5221 from rocallahan/typed-stringf

Introduce variadic template implementation of `stringf` that supports `std::string` parameters

backends/verilog/verilog_backend.cc

@@ -1163,9 +1163,9 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 		dump_sigspec(f, cell->getPort(ID::Y));
 		f << stringf(" = ~((");
 		dump_cell_expr_port(f, cell, "A", false);
-		f << stringf(cell->type == ID($_AOI3_) ? " & " : " | ");
+		f << (cell->type == ID($_AOI3_) ? " & " : " | ");
 		dump_cell_expr_port(f, cell, "B", false);
-		f << stringf(cell->type == ID($_AOI3_) ? ") |" : ") &");
+		f << (cell->type == ID($_AOI3_) ? ") |" : ") &");
 		dump_attributes(f, "", cell->attributes, " ");
 		f << stringf(" ");
 		dump_cell_expr_port(f, cell, "C", false);
@@ -1178,13 +1178,13 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 		dump_sigspec(f, cell->getPort(ID::Y));
 		f << stringf(" = ~((");
 		dump_cell_expr_port(f, cell, "A", false);
-		f << stringf(cell->type == ID($_AOI4_) ? " & " : " | ");
+		f << (cell->type == ID($_AOI4_) ? " & " : " | ");
 		dump_cell_expr_port(f, cell, "B", false);
-		f << stringf(cell->type == ID($_AOI4_) ? ") |" : ") &");
+		f << (cell->type == ID($_AOI4_) ? ") |" : ") &");
 		dump_attributes(f, "", cell->attributes, " ");
 		f << stringf(" (");
 		dump_cell_expr_port(f, cell, "C", false);
-		f << stringf(cell->type == ID($_AOI4_) ? " & " : " | ");
+		f << (cell->type == ID($_AOI4_) ? " & " : " | ");
 		dump_cell_expr_port(f, cell, "D", false);
 		f << stringf("));\n");
 		return true;
@@ -1395,10 +1395,10 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 		int s_width = cell->getPort(ID::S).size();
 		std::string func_name = cellname(cell);
 
-		f << stringf("%s" "function [%d:0] %s;\n", indent.c_str(), width-1, func_name.c_str());
+		f << stringf("%s" "function [%d:0] %s;\n", indent, width-1, func_name);
-		f << stringf("%s" "  input [%d:0] a;\n", indent.c_str(), width-1);
+		f << stringf("%s" "  input [%d:0] a;\n", indent, width-1);
-		f << stringf("%s" "  input [%d:0] b;\n", indent.c_str(), s_width*width-1);
+		f << stringf("%s" "  input [%d:0] b;\n", indent, s_width*width-1);
-		f << stringf("%s" "  input [%d:0] s;\n", indent.c_str(), s_width-1);
+		f << stringf("%s" "  input [%d:0] s;\n", indent, s_width-1);
 
 		dump_attributes(f, indent + "  ", cell->attributes);
 		if (noparallelcase)
@@ -1407,7 +1407,7 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 			if (!noattr)
 				f << stringf("%s" "  (* parallel_case *)\n", indent.c_str());
 			f << stringf("%s" "  casez (s)", indent.c_str());
-			f << stringf(noattr ? " // synopsys parallel_case\n" : "\n");
+			f << (noattr ? " // synopsys parallel_case\n" : "\n");
 		}
 
 		for (int i = 0; i < s_width; i++)

kernel/io.cc

@@ -384,4 +384,153 @@ std::string escape_filename_spaces(const std::string& filename)
 	return out;
 }
 
+void format_emit_unescaped(std::string &result, std::string_view fmt)
+{
+	result.reserve(result.size() + fmt.size());
+	for (size_t i = 0; i < fmt.size(); ++i) {
+		char ch = fmt[i];
+		result.push_back(ch);
+		if (ch == '%' && i + 1 < fmt.size() && fmt[i + 1] == '%') {
+			++i;
+		}
+	}
+}
+
+std::string unescape_format_string(std::string_view fmt)
+{
+	std::string result;
+	format_emit_unescaped(result, fmt);
+	return result;
+}
+
+static std::string string_view_stringf(std::string_view spec, ...)
+{
+	std::string fmt(spec);
+	char format_specifier = fmt[fmt.size() - 1];
+	switch (format_specifier) {
+	case 'd':
+	case 'i':
+	case 'o':
+	case 'u':
+	case 'x':
+	case 'X': {
+		// Strip any length modifier off `fmt`
+		std::string long_fmt;
+		for (size_t i = 0; i + 1 < fmt.size(); ++i) {
+			char ch = fmt[i];
+			if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
+				break;
+			}
+			long_fmt.push_back(ch);
+		}
+		// Add `lld` or whatever
+		long_fmt += "ll";
+		long_fmt.push_back(format_specifier);
+		fmt = long_fmt;
+		break;
+	}
+	default:
+		break;
+	}
+
+	va_list ap;
+	va_start(ap, spec);
+	std::string result = vstringf(fmt.c_str(), ap);
+	va_end(ap);
+	return result;
+}
+
+template <typename Arg>
+static void format_emit_stringf(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, Arg arg)
+{
+	// Delegate nontrivial formats to the C library.
+	switch (num_dynamic_ints) {
+	case DynamicIntCount::NONE:
+		result += string_view_stringf(spec, arg);
+		return;
+	case DynamicIntCount::ONE:
+		result += string_view_stringf(spec, dynamic_ints[0], arg);
+		return;
+	case DynamicIntCount::TWO:
+		result += string_view_stringf(spec, dynamic_ints[0], dynamic_ints[1], arg);
+		return;
+	}
+	YOSYS_ABORT("Internal error");
+}
+
+void format_emit_long_long(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, long long arg)
+{
+	if (spec == "%d") {
+		// Format checking will have guaranteed num_dynamic_ints == 0.
+		result += std::to_string(arg);
+		return;
+	}
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, arg);
+}
+
+void format_emit_unsigned_long_long(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, unsigned long long arg)
+{
+	if (spec == "%u") {
+		// Format checking will have guaranteed num_dynamic_ints == 0.
+		result += std::to_string(arg);
+		return;
+	}
+	if (spec == "%c") {
+		result += static_cast<char>(arg);
+		return;
+	}
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, arg);
+}
+
+void format_emit_double(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, double arg)
+{
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, arg);
+}
+
+void format_emit_char_ptr(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, const char *arg)
+{
+	if (spec == "%s") {
+		// Format checking will have guaranteed num_dynamic_ints == 0.
+		result += arg;
+		return;
+	}
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, arg);
+}
+
+void format_emit_string(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, const std::string &arg)
+{
+	if (spec == "%s") {
+		// Format checking will have guaranteed num_dynamic_ints == 0.
+		result += arg;
+		return;
+	}
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, arg.c_str());
+}
+
+void format_emit_string_view(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, std::string_view arg)
+{
+	if (spec == "%s") {
+		// Format checking will have guaranteed num_dynamic_ints == 0.
+		// We can output the string without creating a temporary copy.
+		result += arg;
+		return;
+	}
+	// Delegate nontrivial formats to the C library. We need to construct
+	// a temporary string to ensure null termination.
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, std::string(arg).c_str());
+}
+
+void format_emit_void_ptr(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, const void *arg)
+{
+	format_emit_stringf(result, spec, dynamic_ints, num_dynamic_ints, arg);
+}
+
 YOSYS_NAMESPACE_END

kernel/io.h

@@ -1,5 +1,6 @@
 #include <string>
 #include <stdarg.h>
+#include <type_traits>
 #include "kernel/yosys_common.h"
 
 #ifndef YOSYS_IO_H
@@ -50,18 +51,391 @@ inline std::string vstringf(const char *fmt, va_list ap)
 #endif
 }
 
-std::string stringf(const char *fmt, ...) YS_ATTRIBUTE(format(printf, 1, 2));
+enum ConversionSpecifier : uint8_t
-
-inline std::string stringf(const char *fmt, ...)
 {
-	std::string string;
+	CONVSPEC_NONE,
-	va_list ap;
+	// Specifier not understood/supported
+	CONVSPEC_ERROR,
+	// Consumes a "long long"
+	CONVSPEC_SIGNED_INT,
+	// Consumes a "unsigned long long"
+	CONVSPEC_UNSIGNED_INT,
+	// Consumes a "double"
+	CONVSPEC_DOUBLE,
+	// Consumes a "const char*"
+	CONVSPEC_CHAR_PTR,
+	// Consumes a "void*"
+	CONVSPEC_VOID_PTR,
+};
 
-	va_start(ap, fmt);
+constexpr ConversionSpecifier parse_conversion_specifier(char ch, char prev_ch)
-	string = vstringf(fmt, ap);
+{
-	va_end(ap);
+	switch (ch) {
+	case 'd':
+	case 'i':
+		return CONVSPEC_SIGNED_INT;
+	case 'o':
+	case 'u':
+	case 'x':
+	case 'X':
+	case 'm':
+		return CONVSPEC_UNSIGNED_INT;
+	case 'c':
+		if (prev_ch == 'l' || prev_ch == 'q' || prev_ch == 'L') {
+			// wchar not supported
+			return CONVSPEC_ERROR;
+		}
+		return CONVSPEC_UNSIGNED_INT;
+	case 'e':
+	case 'E':
+	case 'f':
+	case 'F':
+	case 'g':
+	case 'G':
+	case 'a':
+	case 'A':
+		return CONVSPEC_DOUBLE;
+	case 's':
+		if (prev_ch == 'l' || prev_ch == 'q' || prev_ch == 'L') {
+			// wchar not supported
+			return CONVSPEC_ERROR;
+		}
+		return CONVSPEC_CHAR_PTR;
+	case 'p':
+		return CONVSPEC_VOID_PTR;
+	case '$': // positional parameters
+	case 'n':
+	case 'S':
+		return CONVSPEC_ERROR;
+	default:
+		return CONVSPEC_NONE;
+	}
+}
 
-	return string;
+enum class DynamicIntCount : uint8_t {
+	NONE = 0,
+	ONE = 1,
+	TWO = 2,
+};
+
+// Describes a printf-style format conversion specifier found in a format string.
+struct FoundFormatSpec
+{
+	// The start offset of the conversion spec in the format string.
+	int start;
+	// The end offset of the conversion spec in the format string.
+	int end;
+	ConversionSpecifier spec;
+	// Number of int args consumed by '*' dynamic width/precision args.
+	DynamicIntCount num_dynamic_ints;
+};
+
+// Ensure there is no format spec.
+constexpr void ensure_no_format_spec(std::string_view fmt, int index, bool *has_escapes)
+{
+	int fmt_size = static_cast<int>(fmt.size());
+	// A trailing '%' is not a format spec.
+	while (index + 1 < fmt_size) {
+		if (fmt[index] != '%') {
+			++index;
+			continue;
+		}
+		if (fmt[index + 1] != '%') {
+			YOSYS_ABORT("More format conversion specifiers than arguments");
+		}
+		*has_escapes = true;
+		index += 2;
+	}
+}
+
+// Returns the next format conversion specifier (starting with '%').
+// Returns CONVSPEC_NONE if there isn't a format conversion specifier.
+constexpr FoundFormatSpec find_next_format_spec(std::string_view fmt, int fmt_start, bool *has_escapes)
+{
+	int index = fmt_start;
+	int fmt_size = static_cast<int>(fmt.size());
+	while (index < fmt_size) {
+		if (fmt[index] != '%') {
+			++index;
+			continue;
+		}
+		int p = index + 1;
+		uint8_t num_dynamic_ints = 0;
+		while (true) {
+			if (p == fmt_size) {
+				return {0, 0, CONVSPEC_NONE, DynamicIntCount::NONE};
+			}
+			if (fmt[p] == '%') {
+				*has_escapes = true;
+				index = p + 1;
+				break;
+			}
+			if (fmt[p] == '*') {
+				if (num_dynamic_ints >= 2) {
+					return {0, 0, CONVSPEC_ERROR, DynamicIntCount::NONE};
+				}
+				++num_dynamic_ints;
+			}
+			ConversionSpecifier spec = parse_conversion_specifier(fmt[p], fmt[p - 1]);
+			if (spec != CONVSPEC_NONE) {
+				return {index, p + 1, spec, static_cast<DynamicIntCount>(num_dynamic_ints)};
+			}
+			++p;
+		}
+	}
+	return {0, 0, CONVSPEC_NONE, DynamicIntCount::NONE};
+}
+
+template <typename... Args>
+constexpr typename std::enable_if<sizeof...(Args) == 0>::type
+check_format(std::string_view fmt, int fmt_start, bool *has_escapes, FoundFormatSpec*, DynamicIntCount)
+{
+	ensure_no_format_spec(fmt, fmt_start, has_escapes);
+}
+
+// Check that the format string `fmt.substr(fmt_start)` is valid for the given type arguments.
+// Fills `specs` with the FoundFormatSpecs found in the format string.
+// `int_args_consumed` is the number of int arguments already consumed to satisfy the
+// dynamic width/precision args for the next format conversion specifier.
+template <typename Arg, typename... Args>
+constexpr void check_format(std::string_view fmt, int fmt_start, bool *has_escapes, FoundFormatSpec* specs,
+        DynamicIntCount int_args_consumed)
+{
+	FoundFormatSpec found = find_next_format_spec(fmt, fmt_start, has_escapes);
+	if (found.num_dynamic_ints > int_args_consumed) {
+		// We need to consume at least one more int for the dynamic
+		// width/precision of this format conversion specifier.
+		if constexpr (!std::is_convertible_v<Arg, int>) {
+			YOSYS_ABORT("Expected dynamic int argument");
+		}
+		check_format<Args...>(fmt, fmt_start, has_escapes, specs,
+			static_cast<DynamicIntCount>(static_cast<uint8_t>(int_args_consumed) + 1));
+		return;
+	}
+	switch (found.spec) {
+	case CONVSPEC_NONE:
+		YOSYS_ABORT("Expected format conversion specifier for argument");
+		break;
+	case CONVSPEC_ERROR:
+		YOSYS_ABORT("Found unsupported format conversion specifier");
+		break;
+	case CONVSPEC_SIGNED_INT:
+		if constexpr (!std::is_convertible_v<Arg, long long>) {
+			YOSYS_ABORT("Expected type convertible to signed integer");
+		}
+		*specs = found;
+		break;
+	case CONVSPEC_UNSIGNED_INT:
+		if constexpr (!std::is_convertible_v<Arg, unsigned long long>) {
+			YOSYS_ABORT("Expected type convertible to unsigned integer");
+		}
+		*specs = found;
+		break;
+	case CONVSPEC_DOUBLE:
+		if constexpr (!std::is_convertible_v<Arg, double>) {
+			YOSYS_ABORT("Expected type convertible to double");
+		}
+		*specs = found;
+		break;
+	case CONVSPEC_CHAR_PTR:
+		if constexpr (!std::is_convertible_v<Arg, const char *> &&
+		        !std::is_convertible_v<Arg, const std::string &> &&
+			!std::is_convertible_v<Arg, const std::string_view &>) {
+			YOSYS_ABORT("Expected type convertible to char *");
+		}
+		*specs = found;
+		break;
+	case CONVSPEC_VOID_PTR:
+		if constexpr (!std::is_convertible_v<Arg, const void *>) {
+			YOSYS_ABORT("Expected pointer type");
+		}
+		*specs = found;
+		break;
+	}
+	check_format<Args...>(fmt, found.end, has_escapes, specs + 1, DynamicIntCount::NONE);
+}
+
+// Emit the string representation of `arg` that has been converted to a `long long'.
+void format_emit_long_long(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, long long arg);
+
+// Emit the string representation of `arg` that has been converted to a `unsigned long long'.
+void format_emit_unsigned_long_long(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, unsigned long long arg);
+
+// Emit the string representation of `arg` that has been converted to a `double'.
+void format_emit_double(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, double arg);
+
+// Emit the string representation of `arg` that has been converted to a `const char*'.
+void format_emit_char_ptr(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, const char *arg);
+
+// Emit the string representation of `arg` that has been converted to a `std::string'.
+void format_emit_string(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, const std::string &arg);
+
+// Emit the string representation of `arg` that has been converted to a `std::string_view'.
+void format_emit_string_view(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, std::string_view arg);
+
+// Emit the string representation of `arg` that has been converted to a `double'.
+void format_emit_void_ptr(std::string &result, std::string_view spec, int *dynamic_ints,
+	DynamicIntCount num_dynamic_ints, const void *arg);
+
+// Emit the string representation of `arg` according to the given `FoundFormatSpec`,
+// appending it to `result`.
+template <typename Arg>
+inline void format_emit_one(std::string &result, std::string_view fmt, const FoundFormatSpec &ffspec,
+	int *dynamic_ints, const Arg& arg)
+{
+	std::string_view spec = fmt.substr(ffspec.start, ffspec.end - ffspec.start);
+	DynamicIntCount num_dynamic_ints = ffspec.num_dynamic_ints;
+	switch (ffspec.spec) {
+	case CONVSPEC_SIGNED_INT:
+		if constexpr (std::is_convertible_v<Arg, long long>) {
+			long long s = arg;
+			format_emit_long_long(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		break;
+	case CONVSPEC_UNSIGNED_INT:
+		if constexpr (std::is_convertible_v<Arg, unsigned long long>) {
+			unsigned long long s = arg;
+			format_emit_unsigned_long_long(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		break;
+	case CONVSPEC_DOUBLE:
+		if constexpr (std::is_convertible_v<Arg, double>) {
+			double s = arg;
+			format_emit_double(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		break;
+	case CONVSPEC_CHAR_PTR:
+		if constexpr (std::is_convertible_v<Arg, const char *>) {
+			const char *s = arg;
+			format_emit_char_ptr(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		if constexpr (std::is_convertible_v<Arg, const std::string &>) {
+			const std::string &s = arg;
+			format_emit_string(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		if constexpr (std::is_convertible_v<Arg, const std::string_view &>) {
+			const std::string_view &s = arg;
+			format_emit_string_view(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		break;
+	case CONVSPEC_VOID_PTR:
+		if constexpr (std::is_convertible_v<Arg, const void *>) {
+			const void *s = arg;
+			format_emit_void_ptr(result, spec, dynamic_ints, num_dynamic_ints, s);
+			return;
+		}
+		break;
+	default:
+		break;
+	}
+	YOSYS_ABORT("Internal error");
+}
+
+// Append the format string `fmt` to `result`, assuming there are no format conversion
+// specifiers other than "%%" and therefore no arguments. Unescape "%%".
+void format_emit_unescaped(std::string &result, std::string_view fmt);
+std::string unescape_format_string(std::string_view fmt);
+
+inline void format_emit(std::string &result, std::string_view fmt, int fmt_start,
+	bool has_escapes, const FoundFormatSpec*, int*, DynamicIntCount)
+{
+	fmt = fmt.substr(fmt_start);
+	if (has_escapes) {
+		format_emit_unescaped(result, fmt);
+	} else {
+		result += fmt;
+	}
+}
+// Format `args` according to `fmt` (starting at `fmt_start`) and `specs` and append to `result`.
+// `num_dynamic_ints` in `dynamic_ints[]` have already been collected to provide as
+// dynamic width/precision args for the next format conversion specifier.
+template <typename Arg, typename... Args>
+inline void format_emit(std::string &result, std::string_view fmt, int fmt_start, bool has_escapes,
+	const FoundFormatSpec* specs, int *dynamic_ints, DynamicIntCount num_dynamic_ints,
+	const Arg &arg, const Args &... args)
+{
+	if (specs->num_dynamic_ints > num_dynamic_ints) {
+		// Collect another int for the dynamic width precision/args
+		// for the next format conversion specifier.
+		if constexpr (std::is_convertible_v<Arg, int>) {
+			dynamic_ints[static_cast<uint8_t>(num_dynamic_ints)] = arg;
+		} else {
+			YOSYS_ABORT("Internal error");
+		}
+		format_emit(result, fmt, fmt_start, has_escapes, specs, dynamic_ints,
+		            static_cast<DynamicIntCount>(static_cast<uint8_t>(num_dynamic_ints) + 1), args...);
+		return;
+	}
+	std::string_view str = fmt.substr(fmt_start, specs->start - fmt_start);
+	if (has_escapes) {
+		format_emit_unescaped(result, str);
+	} else {
+		result += str;
+	}
+	format_emit_one(result, fmt, *specs, dynamic_ints, arg);
+	format_emit(result, fmt, specs->end, has_escapes, specs + 1, dynamic_ints, DynamicIntCount::NONE, args...);
+}
+
+template <typename... Args>
+inline std::string format_emit_toplevel(std::string_view fmt, bool has_escapes, const FoundFormatSpec* specs, const Args &... args)
+{
+	std::string result;
+	int dynamic_ints[2] = { 0, 0 };
+	format_emit(result, fmt, 0, has_escapes, specs, dynamic_ints, DynamicIntCount::NONE, args...);
+	return result;
+}
+template <>
+inline std::string format_emit_toplevel(std::string_view fmt, bool has_escapes, const FoundFormatSpec*)
+{
+	if (!has_escapes) {
+		return std::string(fmt);
+	}
+	return unescape_format_string(fmt);
+}
+
+// This class parses format strings to build a list of `FoundFormatSpecs` in `specs`.
+// When the compiler supports `consteval` (C++20), this parsing happens at compile time and
+// type errors will be reported at compile time. Otherwise the parsing happens at
+// runtime and type errors will trigger an `abort()` at runtime.
+template <typename... Args>
+class FmtString
+{
+public:
+	// Implicit conversion from const char * means that users can pass
+	// C string constants which are automatically parsed.
+	YOSYS_CONSTEVAL FmtString(const char *p) : fmt(p)
+	{
+		check_format<Args...>(fmt, 0, &has_escapes, specs, DynamicIntCount::NONE);
+	}
+	std::string format(const Args &... args)
+	{
+		return format_emit_toplevel(fmt, has_escapes, specs, args...);
+	}
+private:
+	std::string_view fmt;
+	bool has_escapes = false;
+	FoundFormatSpec specs[sizeof...(Args)] = {};
+};
+
+template <typename T> struct WrapType { using type = T; };
+template <typename T> using TypeIdentity = typename WrapType<T>::type;
+
+template <typename... Args>
+inline std::string stringf(FmtString<TypeIdentity<Args>...> fmt, Args... args)
+{
+	return fmt.format(args...);
 }
 
 int readsome(std::istream &f, char *s, int n);

kernel/yosys_common.h

@@ -134,6 +134,15 @@
 #  define YS_COLD
 #endif
 
+#ifdef __cpp_consteval
+#define YOSYS_CONSTEVAL consteval
+#else
+// If we can't use consteval we can at least make it constexpr.
+#define YOSYS_CONSTEVAL constexpr
+#endif
+
+#define YOSYS_ABORT(s) abort()
+
 #include "kernel/io.h"
 
 YOSYS_NAMESPACE_BEGIN