Fix pinning (schemars and MSRV)

Done as is single patch to make sure all the docs and CI are in sync and
correct.

We currently pin the `schemars` dependency using `<=0.8.3` as well as a
the `dyn-clone` transient dependency in the manifest (`hashes` and the
extended test crate). This is incorrect because it makes usage of the
crate klunky (or possibly impossible) if downstream users wish to use a
later version of `schemars`.

Observe also that we do not have to pin `schemars`, we do however have to pin
the `serde` crate if either `serde` or `schemars` features are enabled.
Do so in CI and document in the readme file within hashes.

Currently we have a pin remaining from the old MSRV (`syn` due to use
of `matches!`).

Fix pinning by:

- Remove pin in manifest for `schemars`
- Fix pinning for MSRV in CI and docs (this includes documenting pinning
  requirements for `schemars` feature because it is related to the other
  pin of `serde`) in both `hashes` readme and main repo readme.

README.md

@@ -77,12 +77,16 @@ For more information please see `./CONTRIBUTING.md`.
 
 This library should always compile with any combination of features on **Rust 1.48.0**.
 
-To build with the MSRV you will need to pin some dependencies:
+To build with the MSRV you will need to pin `serde` (if you have the feature enabled)
+
 ```
+# serde 1.0.157 uses syn 2.0 which requires edition 2021
 cargo update -p serde --precise 1.0.156
-cargo update -p syn --precise 1.0.107
 ```
 
+before building. (And if your code is a library, your downstream users will need to run these
+commands, and so on.)
+
 ## Installing Rust
 
 Rust can be installed using your package manager of choice or

bitcoin/contrib/test.sh

@@ -27,8 +27,6 @@ fi
 if cargo --version | grep "1\.48"; then
     # 1.0.157 uses syn 2.0 which requires edition 2018
     cargo update -p serde --precise 1.0.156
-    # 1.0.108 uses `matches!` macro so does not work with Rust 1.41.1, bad `syn` no biscuit.
-    cargo update -p syn --precise 1.0.107
 fi
 
 # We should not have any duplicate dependencies. This catches mistakes made upgrading dependencies

hashes/Cargo.toml

@@ -16,7 +16,6 @@ exclude = ["tests", "contrib"]
 default = ["std"]
 std = ["alloc", "internals/std"]
 alloc = ["internals/alloc"]
-schemars = ["actual-schemars", "dyn-clone"]
 serde-std = ["serde/std"]
 
 [package.metadata.docs.rs]
@@ -27,13 +26,9 @@ rustdoc-args = ["--cfg", "docsrs"]
 internals = { path = "../internals", package = "bitcoin-private", version = "0.1.0" }
 
 core2 = { version = "0.3.0", default_features = false, optional = true }
+schemars = { version = "0.8.3", optional = true }
 # Only enable this if you explicitly do not want to use "std", otherwise enable "serde-std".
 serde = { version = "1.0", default-features = false, optional = true }
-# Do NOT use this as a feature! Use the `schemars` feature instead. Can only be used with "std" enabled.
-actual-schemars = { package = "schemars", version = "<=0.8.3", optional = true }
-# Do NOT enable this dependency, this is just to pin dyn-clone (transitive dep from schemars)
-# because 1.0.8 does not build with Rust 1.41.1 (because of useage of `Arc::as_ptr`).
-dyn-clone = { version = "<=1.0.7", default_features = false, optional = true }
 
 [dev-dependencies]
 serde_test = "1.0"

hashes/README.md

@@ -13,6 +13,18 @@ since these are needed to display hashes anway.
 
 This library should always compile with any combination of features on **Rust 1.48.0**.
 
+
+To build with the MSRV you will need to pin `serde` (if you have either the `serde` or the
+`schemars` feature enabled)
+
+```
+# serde 1.0.157 uses syn 2.0 which requires edition 2021
+cargo update -p serde --precise 1.0.156
+```
+
+before building. (And if your code is a library, your downstream users will need to run these
+commands, and so on.)
+
 ## Contributions
 
 Contributions are welcome, including additional hash function implementations.

hashes/contrib/test.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 set -ex
 
@@ -17,6 +17,12 @@ if cargo --version | grep nightly >/dev/null; then
     NIGHTLY=true
 fi
 
+# Pin dependencies as required if we are using MSRV toolchain.
+if cargo --version | grep "1\.48"; then
+    # 1.0.157 uses syn 2.0 which requires edition 2021
+    cargo update -p serde --precise 1.0.156
+fi
+
 # Make all cargo invocations verbose
 export CARGO_TERM_VERBOSE=true
 
@@ -52,8 +58,12 @@ if [ "$DO_FEATURE_MATRIX" = true ]; then
     cargo test --no-default-features --features="std,schemars"
 fi
 
+REPO_DIR=$(git rev-parse --show-toplevel)
+
 if [ "$DO_SCHEMARS_TESTS" = true ]; then
-    (cd extended_tests/schemars && cargo test)
+    pushd "$REPO_DIR/hashes/extended_tests/schemars" > /dev/null
+    cargo test
+    popd > /dev/null
 fi
 
 # Build the docs if told to (this only works with the nightly toolchain)

hashes/extended_tests/schemars/Cargo.toml

@@ -13,8 +13,8 @@ path = "../.."
 features = ['schemars', 'serde']
 
 [dependencies]
-jsonschema-valid = "^0.4.0"
+jsonschema-valid = "0.4.0"
 serde = { version = "1.0", default-features = false}
-schemars = { version = "<=0.8.3"}
+schemars = "0.8.3"
 serde_test = "1.0"
 serde_json = "1.0"

hashes/extended_tests/schemars/README.md

@@ -0,0 +1,10 @@
+# Test crate for the schemars feature
+
+Run as usual with `cargo test`.
+
+## Minimum Supported Rust Version (MSRV)
+
+To run the tests with the MSRV you will need to pin some dependencies:
+
+- `cargo update -p serde --precise 1.0.156`
+- `cargo update -p syn --precise 1.0.107`

hashes/src/lib.rs

@@ -113,7 +113,7 @@ pub mod _export {
 }
 
 #[cfg(feature = "schemars")]
-extern crate actual_schemars as schemars;
+extern crate schemars;
 
 mod internal_macros;
 #[macro_use]