Require rust >= 1.25 and drop libc_align conditional

This is mostly taken from Josh's work at [1], I just updated to account
for conflicts and new uses of `libc_align`.

[1]: rust-lang#2845

Co-authored-by: Josh Triplett <josh@joshtriplett.org>

Cargo.toml

@@ -139,10 +139,13 @@ rustc-std-workspace-core = { version = "1.0.0", optional = true }
 [features]
 default = ["std"]
 std = []
-align = []
 rustc-dep-of-std = ['align', 'rustc-std-workspace-core']
 extra_traits = []
 const-extern-fn = []
+
+# `align` is deprecated and no longer does anything
+align = []
+
 # use_std is deprecated, use `std` instead
 use_std = ['std']
 

build.rs

@@ -14,7 +14,6 @@ const ALLOWED_CFGS: &'static [&'static str] = &[
     "freebsd13",
     "freebsd14",
     "freebsd15",
-    "libc_align",
     "libc_cfg_target_vendor",
     "libc_const_extern_fn",
     "libc_const_extern_fn_unstable",
@@ -51,7 +50,6 @@ fn main() {
 
     let (rustc_minor_ver, is_nightly) = rustc_minor_nightly();
     let rustc_dep_of_std = env::var("CARGO_FEATURE_RUSTC_DEP_OF_STD").is_ok();
-    let align_cargo_feature = env::var("CARGO_FEATURE_ALIGN").is_ok();
     let const_extern_fn_cargo_feature = env::var("CARGO_FEATURE_CONST_EXTERN_FN").is_ok();
     let libc_ci = env::var("LIBC_CI").is_ok();
     let libc_check_cfg = env::var("LIBC_CHECK_CFG").is_ok() || rustc_minor_ver >= 80;
@@ -96,11 +94,6 @@ fn main() {
         set_cfg("libc_deny_warnings");
     }
 
-    // Rust >= 1.25 supports repr(align):
-    if rustc_minor_ver >= 25 || rustc_dep_of_std || align_cargo_feature {
-        set_cfg("libc_align");
-    }
-
     // Rust >= 1.26 supports i128 and u128:
     if rustc_minor_ver >= 26 || rustc_dep_of_std {
         set_cfg("libc_int128");

libc-test/build.rs

@@ -67,12 +67,7 @@ fn do_ctest() {
 
 fn ctest_cfg() -> ctest::TestGenerator {
     let mut cfg = ctest::TestGenerator::new();
-    let libc_cfgs = [
-        "libc_align",
-        "libc_core_cvoid",
-        "libc_packedN",
-        "libc_thread_local",
-    ];
+    let libc_cfgs = ["libc_core_cvoid", "libc_packedN", "libc_thread_local"];
     for f in &libc_cfgs {
         cfg.cfg(f, None);
     }