string::new_struct_to_str and io::struct_to_format to dump struct data. io::print will now print structs.

lib/std/core/runtime.c3

@@ -4,7 +4,7 @@
 module std::core::runtime;
 import libc, std::time, std::io, std::sort;
 
-struct ReflectedParam @if(!$defined(ReflectedParam))
+struct ReflectedParam (Printable) @if(!$defined(ReflectedParam))
 {
 	String name;
 	typeid type;

lib/std/core/string.c3

@@ -1,5 +1,6 @@
 module std::core::string;
 import std::ascii;
+import std::io;
 
 distinct String @if(!$defined(String)) = inline char[];
 distinct ZString = inline char*;
@@ -749,4 +750,15 @@ fn String! Splitter.next(&self)
 	return remaining;
 }
 
+macro String new_struct_to_str(x, Allocator allocator = allocator::heap())
+{
+	DString s;
+	@stack_mem(512; Allocator mem)
+	{
+		s.new_init(allocator: mem);
+		io::fprint(&s, x)!!;
+	};
+	return s.copy_str(allocator);
+}
 
+macro String temp_struct_to_str(x) => new_struct_to_str(x, allocator::temp());

lib/std/io/formatter.c3

@@ -23,6 +23,45 @@ fault PrintFault
 def OutputFn = fn void!(void* buffer, char c);
 def FloatType = double;
 
+
+macro bool is_struct_with_default_print($Type)
+{
+	return $Type.kindof == STRUCT
+		&&& !$defined($Type.to_format)
+		&&& !$defined($Type.to_new_string);
+}
+
+<*
+ Introspect a struct and print it to a formatter
+
+ @require @typekind(value) == STRUCT `This macro is only valid on macros`
+*>
+macro usz! struct_to_format(value, Formatter* f, bool $force_dump)
+{
+    var $Type = $typeof(value);
+    usz total = f.print("{ ")!;
+    $foreach ($i, $member : $Type.membersof)
+        $if $i > 0:
+            total += f.print(", ")!;
+        $endif
+        $if $member.nameof != "":
+            total += f.printf("%s: ", $member.nameof)!;
+		$endif
+		$if ($force_dump &&& $member.typeid.kindof == STRUCT) |||
+			is_struct_with_default_print($typefrom($member.typeid)):
+			total += struct_to_format($member.get(value), f, $force_dump)!;
+		$else
+			total += f.printf("%s", $member.get(value))!;
+		$endif
+	$endforeach
+	return total + f.print(" }");
+}
+
+fn usz! ReflectedParam.to_format(&self, Formatter* f) @dynamic
+{
+	return f.printf("[Parameter '%s']", self.name);
+}
+
 fn usz! Formatter.printf(&self, String format, args...)
 {
 	return self.vprintf(format, args) @inline;
@@ -159,12 +198,6 @@ fn usz! Formatter.out_str(&self, any arg) @private
 			assert(i < arg.type.names.len, "Illegal enum value found, numerical value was %d.", i);
 			return self.out_substr(arg.type.names[i]);
 		case STRUCT:
-			if (arg.type == ReflectedParam.typeid)
-			{
-				ReflectedParam* param = arg.ptr;
-				return self.out_substr("[Parameter '")
-					+  self.out_substr(param.name) + self.out_substr("']");
-			}
 			return self.out_substr("<struct>");
 		case UNION:
 			return self.out_substr("<union>");

lib/std/io/io.c3

@@ -122,7 +122,13 @@ macro usz! fprint(out, x)
 			$if $assignable(x, String):
 				return out.write((String)x);
 			$else
-				return fprintf(out, "%s", x);
+				$if is_struct_with_default_print($Type):
+					Formatter formatter;
+                    formatter.init(&out_putstream_fn, &&(OutStream)out);
+                    return struct_to_format(x, &formatter, false);
+				$else
+					return fprintf(out, "%s", x);
+				$endif
 			$endif
 	$endswitch
 }

releasenotes.md

@@ -19,6 +19,8 @@
 - Adding constants to the Json AST #1540
 - Adding info to the globals inside Json AST #1541
 - Null-check function pointer invocation #1573.
+- `string::new_struct_to_str` and `io::struct_to_format` to dump struct data.
+- `io::print` will now print structs.
 
 ### Fixes
 - `Unsupported int[*] $x = { 1, 2, 3, 4 }` #1489.

test/test_suite/debug_symbols/defer_macro.c3t

@@ -680,7 +680,7 @@ no_match:                                         ; preds = %compare
 !90 = !DIFile(filename: "io.c3"
 !91 = !DILocation(line: 42, column: 7, scope: !78)
 !92 = !DILocalVariable(name: "len"
-!93 = distinct !DISubprogram(name: "fprintn", linkageName: "fprintn", scope: !90, file: !90, line: 166, scopeLine: 166, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !5, retainedNodes: !20)
+!93 = distinct !DISubprogram(name: "fprintn", linkageName: "fprintn", scope: !90
 !94 = !DILocation
 !95 = !DILocation
 !96 = !DILocation