Calculating $(ManagedXamlResourcesDirectory) is taking ~2% of evaluation for a solution-wide design-time build

[davkean]

From: dotnet/sdk#1586.

Pass	File	Line #	Expression	Inc (ms)	Inc (%)	Exc (ms)	Exc (%)	#	Bug
Total Evaluation				6159	100%	54	0.9%
Properties (Pass 1)				3312	53.8%	9	0.1%
ItemDefinitionGroup (Pass 2)				14	0.2%	2	0%
Items (Pass 3)				566	9.2%	24	0.4%
Lazy Items (Pass 3.1)				1826	29.6%	158	2.6%
UsingTasks (Pass 4)				59	1%	59	1%
Targets (Pass 5)				327	5.3%	208	3.4%
Properties (Pass 1)	Microsoft.Managed.DesignTime.targets	46	<ManagedXamlResourcesDirectory Condition="!Exists('$(ManagedXamlResourcesDirectory)')" >$(MSBuildThi...	118	1.9%	115	1.9%	223

https://github.com/dotnet/project-system/blob/master/src/Microsoft.VisualStudio.ProjectSystem.Managed/ProjectSystem/DesignTimeTargets/Microsoft.Managed.DesignTime.targets#L46

[nguerrera]

Two thoughts on this if the binder rewrite gets punted:

1. It might be sinplest if the project system just calculated the resource directory once and passed it in.

2. Does $([MSBuild]::Add(0, $(Value))) help bind straight to integers? I've used a variant of that once in to force an arg to string.format to be treated as an int.

[davkean]

Good ideas, still trying to mash my binder changes in without a complete rewrite - which is proving to be difficult.

[davkean]

Going to dup this against: dotnet/msbuild#2217, ~50% of this cost is the exceptions.