`./configure --set changelog-seen=2` doesn't work

[jyn514]

; ./configure --set changelog-seen=2
configure: processing command line
configure: 
configure: changelog-seen       := 2
configure: build.configure-args := ['--set', 'changelog-seen=2']
Traceback (most recent call last):
  File "/Users/jyn/src/rust/./src/bootstrap/configure.py", line 465, in <module>
    raise RuntimeError("config key {} not in sections".format(section_key))
RuntimeError: config key changelog-seen not in sections

The problem is that the configure script assumes that all keys are in a section and there are no top-level keys. This forces people to use printf instead:

rust/README.md

Lines 89 to 96 in 37c1d6d

	The Rust build system uses a file named `config.toml` in the root of the
	source tree to determine various configuration settings for the build.
	Set up the defaults intended for distros to get started. You can see a full list of options
	in `config.toml.example`.
	```sh
	printf 'profile = "user" \nchangelog-seen = 2 \n' > config.toml
	```

We should make it possible to set top-level keys through configure, both changelog-seen and profile. We should also update the line in the readme linked above to suggest ./configure instead of printf.

[jyn514]

Mentoring instructions: look around

rust/src/bootstrap/configure.py

Lines 462 to 471 in 37c1d6d

	for section_key in config:
	section_config = config[section_key]
	if section_key not in sections:
	raise RuntimeError("config key {} not in sections".format(section_key))
	if section_key == 'target':
	for target in section_config:
	configure_section(targets[target], section_config[target])
	else:
	configure_section(sections[section_key], section_config)

I think the fix would be something like if section_config is None: # special-casing for top-level keys.

[shourya5]

@claim

[shourya5]

In the configure.py, from where exactly do we get the top-level keys? from the set function?

[jyn514]

In the configure.py, from where exactly do we get the top-level keys? from the set function?

I'm not sure off the top of my head. How could you find out that information?

[lionellloh]

@shourya5 Hi are you still working on this?

[zephaniahong]

@jyn514 do you think it's okay to unassign @shourya5 ?
This issue is blocking #107050 as well.

[zephaniahong]

@lionellloh Since there's no response from the assignee, I think you can take the issue. Are you still keen on working on this issue?