Reset MSRV to 1.65 by not running the generic tests on older rustc version

The code compiles fine, but using it require more recent rustc version

Author: Luthaf

.github/workflows/tests.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        rust-version: ["1.78", stable, beta, nightly]
+        rust-version: ["1.65", stable, beta, nightly]
     steps:
       - uses: actions/checkout@v3
         with:

Cargo.toml

@@ -2,7 +2,7 @@
 name = "soa_derive"
 version = "0.13.0"
 edition = "2018"
-rust-version = "1.78"
+rust-version = "1.65"
 
 authors = ["Guillaume Fraux <[email protected]>"]
 license = "MIT/Apache-2.0"
@@ -28,6 +28,9 @@ bencher = "0.1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 
+[build-dependencies]
+rustc_version = "0.4"
+
 [[bench]]
 name = "soa"
-harness = false
+harness = false

build.rs

@@ -0,0 +1,7 @@
+use rustc_version::Version;
+
+fn main() {
+    if rustc_version::version().unwrap() >= Version::parse("1.78.0").unwrap() {
+        println!("cargo:rustc-cfg=rustc_is_at_least_1_78");
+    }
+}

soa-derive-internal/Cargo.toml

@@ -2,7 +2,7 @@
 name = "soa_derive_internal"
 version = "0.13.4"
 edition = "2018"
-rust-version = "1.63"
+rust-version = "1.65"
 
 authors = ["Guillaume Fraux <[email protected]>"]
 license = "MIT/Apache-2.0"

tests/generic.rs

@@ -1,3 +1,6 @@
+#![allow(unexpected_cfgs)]
+#![cfg(rustc_is_at_least_1_78)]
+
 mod particles;
 use std::marker::PhantomData;
 use std::fmt::Debug;