Only upgrade .NET tools when an update is available instead of reinstalling everytime

[thecatcore]

Standards checklist:

• The PR title is descriptive.
• I have read CONTRIBUTING.md
• The code compiles (cargo build)
• The code passes rustfmt (cargo fmt)
• The code passes clippy (cargo clippy)
• The code passes tests (cargo test)
• Optional: I have tested the code myself

For new steps

• Optional: Topgrade skips this step where needed
• Optional: The --dry-run option works with this step
• Optional: The --yes option works with this step if it is supported by
  the underlying command

If you developed a feature or a bug fix for someone else and you do not have the
means to test it, please tag this person here.

[SteveLauC]

So even if an update is not available, dotnet tool update <package> will still update (reinstall) it?

[SteveLauC]

I just tried it on my host, and it seems that dotnet update will reinstall a package even though it is already the latest version:

$ dotnet tool list --global
Package Id       Version         Commands
--------------------------------------------
dotnet-dump      7.0.447801      dotnet-dump

$ stat ~/.dotnet/tools/dotnet-dump
  File: /home/steve/.dotnet/tools/dotnet-dump
  Size: 97448           Blocks: 192        IO Block: 4096   regular file
Device: 0,41    Inode: 2044812     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/   steve)   Gid: ( 1000/   steve)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2023-10-14 19:41:35.939916631 +0800
Modify: 2023-10-14 19:41:35.938916648 +0800
Change: 2023-10-14 19:41:35.946916515 +0800
 Birth: 2023-10-14 19:41:35.938916648 +0800

$ dotnet tool update dotnet-dump --global
Tool 'dotnet-dump' was reinstalled with the latest stable version (version '7.0.447801').

$ stat ~/.dotnet/tools/dotnet-dump
  File: /home/steve/.dotnet/tools/dotnet-dump
  Size: 97448           Blocks: 192        IO Block: 4096   regular file
Device: 0,41    Inode: 2044937     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/   steve)   Gid: ( 1000/   steve)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2023-10-14 19:42:36.953904808 +0800
Modify: 2023-10-14 19:42:36.953904808 +0800
Change: 2023-10-14 19:42:36.960904692 +0800
 Birth: 2023-10-14 19:42:36.952904825 +0800

[SteveLauC]

It seems that dotnet search <PKG> won't output this header if <PKG> is not found:

$ dotnet tool search rust
Could not find any results.

Will this happen if the package has already been installed?

[SteveLauC]

If an installed package listed by dotnet tool list --global is guaranteed to be found with dotnet tool search <PKG>, then we can use the --take 1 option to find the exact match:

$ dotnet tool search dotnet-dump
Package ID                     Latest Version      Authors               Downloads      Verified
------------------------------------------------------------------------------------------------
dotnet-dump                    7.0.447801          Microsoft             21089065
dotnet-gcdump                  7.0.447801          Microsoft             9036932
dumpdiag                       0.10.0              DumpDiag              2427
netspark.tools.dumpconfig      1.0.0               Gennadii Kostrov      286

$ dotnet tool search dotnet-dump --take 1
Package ID       Latest Version      Authors        Downloads      Verified
---------------------------------------------------------------------------
dotnet-dump      7.0.447801          Microsoft      21089065

[thecatcore]

It seems like dotnet tool doesn't take into account whether the tool version supports the installed toolchain or not.
For example for package dotnet-ef, a few days ago version 8.0.0 released, dropping support for pre-dotnet-8.0, but the cli still tried installing the update, and it's still showing as latest available using dotnet tool search. Even tho I only had 6.0 and 7.0 installed.