Exclude examples from tower-http dependencies and MSRV inspection

[tottoto]

Feature Request

Motivation

The motivation to exclude examples from tower-http dependencies and MSRV inspection is to improve ci robustness and allow us to free from tower-http's limitations such as MSRV in examples. As tower-http is relatively lower layer library and it's real world examples tend to use a lot of crates as dependencies, treating their dependencies together impose extra limitations. I think these limitations might not be worthy for tower-http.

Proposal

This proposal and the alternative's content are thanks to #372 (comment).

Declares default-members = ["tower-http"] in the workspace manifest, and remove --workspace from all the CI jobs.

Alternatives

Moves examples to its own workspace. But this is not a good idea as decreases development experience with rust-analyzer.

[tottoto]

This proposal seems not to work out as follows.

---

Declares default-menbers at Cargo.toml as

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,4 +1,5 @@
 [workspace]
+default-members = ["tower-http"]
 members = [
   "tower-http",
   "examples/*",

and disable env-filters of tracing-subscriber at tower-http/Cargo.toml to remove duplicate regex-syntax dependency detected by cargo-deny.

--- a/tower-http/Cargo.toml
+++ b/tower-http/Cargo.toml
@@ -47,7 +47,7 @@ hyper = { version = "0.14", features = ["full"] }
 once_cell = "1"
 tokio = { version = "1", features = ["full"] }
 tower = { version = "0.4.10", features = ["buffer", "util", "retry", "make", "timeout"] }
-tracing-subscriber = "0.3"
+tracing-subscriber = { version = "0.3", default_features = false, features = ["fmt"] }
 uuid = { version = "1.0", features = ["v4"] }
 serde_json = "1.0"
 zstd = "0.11"

cargo-deny still reports duplicate regex-syntax as follows though it is not depended by tower-http.

$ cargo deny --all-features --manifest-path ./tower-http/Cargo.toml check
error[duplicate]: found 2 duplicate entries for crate 'regex-syntax'
   ┌─ /home/test/tower-http/Cargo.lock:74:1
   │
74 │ ╭ regex-syntax 0.6.29 registry+https://github.com/rust-lang/crates.io-index
75 │ │ regex-syntax 0.7.2 registry+https://github.com/rust-lang/crates.io-index
   │ ╰────────────────────────────────────────────────────────────────────────^ lock entries
   │
   = regex-syntax v0.6.29
     └── regex-automata v0.1.10
         └── matchers v0.1.0
             └── tracing-subscriber v0.3.17
                 └── (dev) tower-http v0.4.0
   = regex-syntax v0.7.2
     └── regex v1.8.4
         └── tracing-subscriber v0.3.17
             └── (dev) tower-http v0.4.0

---

When removing examples/* for testing as follows, this does not occur.

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,5 +1,6 @@
 [workspace]
+default-members = ["tower-http"]
 members = [
   "tower-http",
-  "examples/*",
+  # "examples/*",
 ]

---

Therefore as cargo-deny seems not to be able to distinguish feature gated dependencies by each members, we might require other approches.

[Jonas Platte]

Yes, this doesn't help for cargo deny, which bases its analysis on Cargo.lock. I think the duplicate dependency should just be allowed in deny.toml.

[tottoto]

Thanks. I opened a pull request #375 to fix cargo-deny test.

[tottoto]

This has already been resolved as the msrv ci is split from examples. And duplicate dependencies checking is changed to warning from deny.