Categorize linking warnings for netcoreapp

[agocke]

To make netcoreapp linkable we need to:

• Get a list of all warnings produced when linking netcoreapp
• Categorize the warnings by product area/namespace
• Identify the cause of the warnings, and propose a fix

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[LakshanF]

Below is the full linker warnings from netcoreapp (699 total)

link.out.txt

And the warning breakdown

Warning	Count
IL2075	164
IL2060	158
IL2070	140
IL2026	53
IL2055	41
IL2057	35
IL2072	33
IL2067	23
IL2080	20
IL2077	15
IL2050	5
IL2082	3
IL2059	2
IL2065	1
IL2087	1
IL2090	1
IL2091	1
IL2079	1
IL2064	1
IL2085	1

[LakshanF]

Warnings by assemblies (low counts are ignored),

Assembly	Cost	Total Warnings	Wrn	Count	Wrn2	Count3	Wrn3	Count4	Wrn4	Count5
System.Private.CoreLib	XL	16	IL2072	4	IL2075	3	IL2057	3	IL2070	3
System.Linq.Expressions	XL	72	IL2075	30	IL2070	22	IL2060	14	IL2077	4
System.Private.Xml	XL	67	IL2070	26	IL2075	22	IL2026	5	IL2072	4
System.Private.CoreLib (Runtime)	XL	46	IL2075	14	IL2026	13	IL2055	6	IL2057	3
System.ComponentModel.TypeConverter	L	60	IL2075	17	IL2057	15	IL2070	8	IL2080	5
Microsoft.CSharp	L?	25	IL2075	14	IL2072	3	IL2070	3	IL2055	2
Microsoft.VisualBasic.Core	L?	25	IL2075	10	IL2070	8	IL2072	2	IL2080	1
System.Security.Cryptography.Algorithms	M	25	IL2026	19	IL2075	4	IL2080	2
System.Data.Common	M	24	IL2057	9	IL2072	6	IL2077	4	IL2080	3
System.Text.Json	M	16	IL2070	7	IL2075	4	IL2026	2	IL2060	2
System.ComponentModel.Annotations	M	11	IL2072	4	IL2070	4	IL2077	2	IL2080	1
System.Runtime.Serialization.Formatters	M	10	IL2070	3	IL2026	2	IL2075	2	IL2067	1
System.Private.DataContractSerialization	M	118	IL2075	41	IL2055	33	IL2060	22	IL2070	16
System.Linq.Queryable	S	110	IL2060	109	IL2067	1
System.Reflection.DispatchProxy	S	11	IL2067	7	IL2072	1	IL2070	1	IL2060	1
System.Text.RegularExpressions	S	8	IL2060	5	IL2070	2	IL2067	1
System.Net.Http.Json	S	6	IL2072	4	IL2077	1	IL2091	1		A
System.Reflection.TypeExtensions	S	31	IL2070	29	IL2026	2
[NO ASSEMBLY INFO]		5	IL2050	5
[Common]		4	IL2070	2	IL2075	2
System.Diagnostics.DiagnosticSource	S	2	IL2070	2
System.Diagnostics.TraceSource	S	2	IL2026	1	IL2070	1
System.ObjectModel	S	2	IL2079	1	IL2057	1
System.Runtime.InteropServices	S	2	IL2070	1	IL2075	1
System.Security.Cryptography.Csp	S	1	IL2026	1
System.Drawing.Primitives	S	1	IL2070	1

Notes/assumption on cost (eerhardt):

1. Assume most of DataContractSerialization work is to mark serialization methods with RequiredUnreferencedCodeAttribute.
2. Linq.Queryable has 106 of the same pattern. Once we solve the pattern, it will only have 3-4 different kinds of warnings.
3. Linq.Expressions cost can be made smaller if our approach is just to mark virtually everything as RequiredUnreferencedCodeAttribute.
4. I'm unsure on CSharp and VB.Core assemblies, so I guessed at L. Can be smaller if most of this is just marking as unsafe.

[marek-safar]

Can we please do it for important RIDs first (each rid can give you different results)

[danmoseley]

added Drawing to table above.

[agocke]

@LakshanF It looks like this is done -- are we ready to close this issue out or is there more investigation necessary for the issues?

[LakshanF]

https://github.com/dotnet/designs/blob/main/accepted/2020/linking-libraries.md gives guidance on fixing warnings