fix: handle no topgrade.toml but files in topgrade.d

[slowsage]

When config file(s) exist in topgrade.d but no topgrade.toml exists, ensure() does not create a default config file. This causes an error as read() assumes the topgrade.toml file exists.

This PR assumes the desired behavior is to use just the contents of the files in topgrade.d.

Else, one could change ensure() to create topgrade.toml.

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
  • I also tested that Topgrade skips the step where needed

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[SteveLauC]

Good catch! I can reproduce the issue that this PR tries to fix with the latest git version of topgrade, and tested that this PR will fix it by using the files under topgrade.d

$ pwd
/home/steve/.config/topgrade.d


$ ls
Permissions Links Size User  Group Date Modified Name
.rw-r--r--@     1  191 steve steve  2 Jun 14:59  topgrade.toml

$ topgrade --dry-run 2>&1 | head -n 2
ERROR Unable to read
ERROR failed to load configuration: No such file or directory (os error 2)
[1]    155988 IOT instruction (core dumped)  topgrade --dry-run 2>&1 |
       155989 done                           head -n 2

I don't have a strong view on how we should handle it under such a case (using files under config.d or creating a default config file), but honestly, I don't like the idea of topgrade.d, IMHO, it really makes the whole thing complicated, topgrade does not have so many configuration entries that it needs to disperse the configuration files across the file system. And if users do want to separate their configuration files into different files, the [include] section is sufficient.

Friendly ping @DottoDev , any thoughts on this?

[slowsage]

Note on topgrade.d: Another complication (and possible future issue) is the the [misc] section. Currently, it is required in the main topgrade.toml file but not in the files in topgrade.d.

[s34m]

IMHO there should be the possibility to use topgrade.d but by default it should automatically use and/or create thetopgrade.toml file at $HOME/.config/

[slowsage]

IMHO there should be the possibility to use topgrade.d but by default it should automatically use and/or create thetopgrade.toml file at $HOME/.config/

Should [misc] be required in the files in topgrade.d?

[s34m]

Best case would be that [misc] isn't required.

[slowsage]

@DottoDev , to confirm:

1. [misc] required in main file (as is currently)
2. Do not process/require [misc] for files in topgrade.d (as is currently)
3. Create topgrade.toml if it doesn't exist even if there are files in topgrade.d

This way the topgrade.toml file can be the only one to have [misc], [include]. Avoiding [include] in topgrade.d avoids some recursive [include] cases.

Please lmk if that makes sense, I'll change the diff to address 3. I'll leave 1. and 2. as is.

[s34m]

@slowsage seems good, but I don't know if topgrade.toml has to be required if topgrade.d exists, imo it doesn't have to be created in this case.

[slowsage]

@DottoDev , this PR handles exactly that case. i.e no topgrade.toml file => use defaults and apply files in topgrade.d if they exist. No file created. Please accept if it makes sense.

[s34m]

Lgtm