fix: support wider range of verbosity settings on other build backends

[henryiii]

See #2338.

This makes the verbosity setting a bit more useful on other backends. This tries to map the current pip meanings to other backends. The key changes are:

• <0 will support uv (feat: option to build directly with uv #2322), build continues to produce a warning. This is a feature that's been requested before for build, btw.
• 1 continues to do nothing on non-pip backends
• 2+ now passes multiple -v to non-pip backends, since both build and uv support adding extra resolving info (similar to pip's -vv) if passing -v.

[mayeut]

Should we be trying to get something consistent between frontends ? i.e. 0 maps to -v with pip

[joerick]

Should we be trying to get something consistent between frontends ? i.e. 0 maps to -v with pip

If we want to keep this option, I like this idea. Previously I was in favour of a light-touch approach to adding arguments to pip wheel. But printing the build backend output by default makes a lot of sense in a CI scenario, and with build the default now, we're just making the option consistent between frontends.

so that would be

	build	pip	uv	desc
-2	not supported	-q	not supported	quiet mode
-1	not supported		-q	reduce output, where supported
0 (default)		-v		print backend output (default)
1	-v	-vv	-v	print log messages e.g. resolving info
2	-vv	-vvv	-vv	print even more debug info

I think it would be nice to warn on unsupported settings i.e. (not supported, above) or outside -2...2.

The other approach, of course, is to avoid this mess, deprecate the build-verbosity option and refer users to build-frontend with the args: param. I'd be open to either, I think.

[henryiii]

That is very similar to what I had, but with one difference: 0 is "native", which doesn't add any flags, keeping to the native behavior of the tool, and allows a user to use the args: if they prefer. If you set verbosity=1, that tells all backends to produce verbose output consistently.

	build	pip	uv	desc
-2	not supported	-q	not supported	quiet mode
-1	not supported		-q	reduce output, where supported
0 (default)				default for build tool
1		-v		print backend output
2	-v	-vv	-v	print log messages e.g. resolving info
3	-vv	-vvv	-vv	print even more debug info

I prefer the default not adding flags (especially since we have a mechanism for users to add flags themselves). I expect most users won't change the default (which now produces build output because it uses build by default), or they'll want build output so they'll set verbose=1, which will produce build output on all backends. Plus this is backwards compatible, the values keep their meanings. Otherwise, 1 becomes too verbose, and a lot of projects have 1 set.

Since this is such an important feature, I like having the flag for it (probably not enough to have added it if we didn't already have it, but certainly happy to keep it). I have a verbose setting for scikit-build-core even though it's possible to manually pass through the verbosity flag go CMake, and it's been popular.

[burgholzer]

Just fyi:
Since 0.6.11, uv also supports -qq. See astral-sh/uv#12300

[joerick]

Yeah, seeing it in a table, I agree with you @henryiii. It's better to have a default that matches the build-frontend's default.

Plus this is backwards compatible, the values keep their meanings. Otherwise, 1 becomes too verbose, and a lot of projects have 1 set.

Also a good point.

[joerick]

I'd consider replacing this with the table from your comment - I think the table does a better job of conveying the meaning, especially with uv soon to be added to the mix.

Suggested change

	* `-1`: Hide as much build output as possible; passes `-q` to the build frontend. Not supported by `build`/`build[uv]`.
	* `0`: The default. On pip, this hides the build output if the build succeeds, other build frontends produce output from the build backend.
	* `1`: Produces build backend output. On `pip`, this passes `-v`. Other frontends do this by default.
	* `2`: Produces extra output from resolving packages too. On `pip`, this passes `-vv`, other build frontends use `-v`.
	* `3`: Even more resolving output from pip with `-vvv`, other build frontends continue to just pass `-v`.
	| | Description | build | pip | uv |
	|-------------|----------------------------------------|-------|-------|------|
	| -2 | quiet mode | N/A | `-q` | N/A |
	| -1 | reduce output, where supported | N/A | ` ` | `-q` |
	| 0 (default) | default for build tool | ` ` | ` ` | ` ` |
	| 1 | print backend output | ` ` | `-v` | ` ` |
	| 2 | print log messages e.g. resolving info | `-v` | `-vv` | `-v` |
	| 3 | print even more debug info | `-vv` | `-vvv` | `-vv` |

[joerick]

I think there are a few changes required here to match the table in your comment. e.g. -1 on pip doesn't do anything. It might be worth changing this to a map, with only a few supported settings per frontend, warning otherwise; up to you.

[henryiii]

Okay, new version. Added the table, and modified it a tiny bit after observing pip wheel . -q and uv build -q look identical, with no output normally. So that's now -1 in the table.

[henryiii]

Also, -vv works on build, even though I don't think it does anything different, I'm only warning and skipping if it is explicitly not supported.