Support ',<number>' to visualize a pointer as an array

[digittigerw]

Hi, with a VC++ project in VS, if I have a pointer like this:
int *myArr = new int[20];

I can watch the pointer "myArr" as an array in "Watch" windows, namely if I enter "myArr,2", it will show "myArr" as an array of int[2] like below

With my MIEngine debugger, that does not work. So my question it, is there a way to do that with MIEngine ? Or is there a workaround ?
Thanks !

[gregg-miskelly]

CC @WardenGnaw

[gregg-miskelly]

@digittigerw I believe you would evaluate something like (int[20])myArr.

@WardenGnaw do I have that right?

[digittigerw]

Yeah, actually (int[20])*myArr works. Thanks for the help ! @WardenGnaw @gregg-miskelly

[gregg-miskelly]

@digittigerw Excellent. I will leave this open to track the possible future feature of supporting ','.

[digittigerw]

@gregg-miskelly Cool. I'm really curious, can we add that support in MIEngine ? is interpretation (parsing) of the watch expression done by VS debugger engine or by debugger extension like MIEngine ?
Issue #709 is my other more general question related to this.

[gregg-miskelly]

The MIEngine has a tiny bit of support for format specifier today. I think the only thing we implemented was ,x and ,d. The array size format specifier could be implemented using this code: https://github.com/Microsoft/MIEngine/blob/72df3ee1ad81a9698a35ced2410016ea9910c5e0/src/MIDebugEngine/Natvis.Impl/Natvis.cs#L501

[Trass3r]

MIEngine/src/MIDebugEngine/Engine.Impl/Variables.cs

Lines 430 to 438 in 4f41195

	// array with static size
	// TODO: could return '(T(*)[n])(exp)' but requires T
	var m = Regex.Match(trimmed, @"^\[?(\d+)\]?$");
	if (m.Success)
	return exp.Substring(0, lastComma);
	// array with dynamic size
	if (Regex.Match(trimmed, @"^\[([a-zA-Z_][a-zA-Z_\d]*)\]$").Success)
	return exp.Substring(0, lastComma);

We could actually use the *array@(len) syntax to make it work.
Though that seems to be gdb only syntax.

[WardenGnaw]

Addressed with:
#1329
#1345