Representation of chained error by LSP

[boozook]

Example from huge workspace.
This from one crate:

This from another crate:

(I'm sorry for ugly theme, it isn't complete yet.

As I know, rust-analyzer as well as cargo reporting these errors in chains.

For example, this is how represents that error by cargo:

for humans:

error[E0107]: struct takes 0 generic arguments but 1 generic argument was supplied
   --> front-crate/src/lib.rs:171:12
    |
171 |     gfx: gfx::Graphics<gfx::api::Cache>,
    |               ^^^^^^^^----------------- help: remove the unnecessary generics
    |               |
    |               expected 0 generic arguments
    |
note: struct defined here, with 0 generic parameters
   --> back-crate/gfx/src/lib.rs:50:12
    |
50  | pub struct Graphics(Api);
    |            ^^^^^^^^

[Spoiler, click me] And in json (look at `children`)

{
	"reason": "compiler-message",
	"package_id": "path+file:///absolute-path-to-front-crate#[email protected]",
	"manifest_path": "/absolute-path-to-front-crate/Cargo.toml",
	"target": {
		"kind": ["lib"],
		"crate_types": ["lib"],
		"name": "front-crate",
		"src_path": "/absolute-path-to-front-crate/src/lib.rs",
		"edition": "2021",
		"doc": true,
		"doctest": true,
		"test": true
	},
	"message": {
		"rendered": "error[E0107]: struct takes 0 generic arguments but 1 generic argument was supplied\n   --> front-crate/src/lib.rs:171:12\n    |\n171 |     gfx: gfx::Graphics<gfx::api::Cache>,\n    |               ^^^^^^^^----------------- help: remove the unnecessary generics\n    |               |\n    |               expected 0 generic arguments\n    |\nnote: struct defined here, with 0 generic parameters\n   --> /abs-path-to-back-crate/gfx/src/lib.rs:50:12\n    |\n50  | pub struct Graphics(Api);\n    |            ^^^^^^^^\n\n",
		"$message_type": "diagnostic",
		"children": [
			{
				"children": [],
				"code": null,
				"level": "note",
				"message": "struct defined here, with 0 generic parameters",
				"rendered": null,
				"spans": [
					{
						"byte_end": 1017,
						"byte_start": 1009,
						"column_end": 20,
						"column_start": 12,
						"expansion": null,
						"file_name": "/abs-path-to-back-crate/gfx/src/lib.rs",
						"is_primary": true,
						"label": null,
						"line_end": 50,
						"line_start": 50,
						"suggested_replacement": null,
						"suggestion_applicability": null,
						"text": [{ "highlight_end": 20, "highlight_start": 12, "text": "pub struct Graphics(Api);" }]
					}
				]
			},
			{
				"children": [],
				"code": null,
				"level": "help",
				"message": "remove the unnecessary generics",
				"rendered": null,
				"spans": [
					{
						"byte_end": 4244,
						"byte_start": 4227,
						"column_end": 37,
						"column_start": 20,
						"expansion": null,
						"file_name": "front-crate/src/lib.rs",
						"is_primary": true,
						"label": null,
						"line_end": 171,
						"line_start": 171,
						"suggested_replacement": "",
						"suggestion_applicability": "MaybeIncorrect",
						"text": [{ "highlight_end": 37, "highlight_start": 20, "text": "\tgfx: gfx::Graphics<gfx::api::Cache>," }]
					}
				]
			}
		],
		"code": {
			"code": "E0107",
			"explanation": "An incorrect number of generic arguments was provided.\n\nErroneous code example:\n\n```compile_fail,E0107\nstruct Foo<T> { x: T }\n\nstruct Bar { x: Foo }             // error: wrong number of type arguments:\n                                  //        expected 1, found 0\nstruct Baz<S, T> { x: Foo<S, T> } // error: wrong number of type arguments:\n                                  //        expected 1, found 2\n\nfn foo<T, U>(x: T, y: U) {}\nfn f() {}\n\nfn main() {\n    let x: bool = true;\n    foo::<bool>(x);                 // error: wrong number of type arguments:\n                                    //        expected 2, found 1\n    foo::<bool, i32, i32>(x, 2, 4); // error: wrong number of type arguments:\n                                    //        expected 2, found 3\n    f::<'static>();                 // error: wrong number of lifetime arguments\n                                    //        expected 0, found 1\n}\n```\n\nWhen using/declaring an item with generic arguments, you must provide the exact\nsame number:\n\n```\nstruct Foo<T> { x: T }\n\nstruct Bar<T> { x: Foo<T> }               // ok!\nstruct Baz<S, T> { x: Foo<S>, y: Foo<T> } // ok!\n\nfn foo<T, U>(x: T, y: U) {}\nfn f() {}\n\nfn main() {\n    let x: bool = true;\n    foo::<bool, u32>(x, 12);              // ok!\n    f();                                  // ok!\n}\n```\n"
		},
		"level": "error",
		"message": "struct takes 0 generic arguments but 1 generic argument was supplied",
		"spans": [
			{
				"byte_end": 4227,
				"byte_start": 4219,
				"column_end": 20,
				"column_start": 12,
				"expansion": null,
				"file_name": "front-crate/src/lib.rs",
				"is_primary": true,
				"label": "expected 0 generic arguments",
				"line_end": 171,
				"line_start": 171,
				"suggested_replacement": null,
				"suggestion_applicability": null,
				"text": [{ "highlight_end": 20, "highlight_start": 12, "text": "\tgfx: gfx::Graphics<gfx::api::Cache>," }]
			}
		]
	}
}

So, currently, each part of a chain of one error is represented in the UI as many independent errors, which is neither correct nor convenient.

---

Idea

My idea is to allow navigation through such chains of errors (or parts of one error).

Also make the command “show this entire error in diagnostics-multibuffer”.

How it's done now:
I can't find the other parts of the error by looking at one of them.

I'm forced to open the whole list of errors and warnings in the diagnostics-multibuffer ("Project Diagnostics") and search for matches by hand.