third pass

Cargo.toml

@@ -12,7 +12,9 @@ repository = "https://github.com/CraneStation/target-lexicon"
 edition = "2018"
 
 [features]
-default = []
+default = ["rust_1_40"]
+# When enabled, use features that are only available with 1.40 or later.
+rust_1_40 = []
 std = []
 
 [badges]

build.rs

@@ -107,15 +107,15 @@ fn write_host_rs(mut out: File, triple: Triple) -> io::Result<()> {
     writeln!(out, "impl Architecture {{")?;
     writeln!(out, "    /// Return the architecture for the current host.")?;
     writeln!(out, "    pub const fn host() -> Self {{")?;
-    writeln!(out, "        Self::{:?}", triple.architecture)?;
+    writeln!(out, "        Architecture::{:?}", triple.architecture)?;
     writeln!(out, "    }}")?;
     writeln!(out, "}}")?;
     writeln!(out)?;
 
     writeln!(out, "impl Vendor {{")?;
     writeln!(out, "    /// Return the vendor for the current host.")?;
     writeln!(out, "    pub const fn host() -> Self {{")?;
-    writeln!(out, "        Self::{}", vendor_display(&triple.vendor))?;
+    writeln!(out, "        Vendor::{}", vendor_display(&triple.vendor))?;
     writeln!(out, "    }}")?;
     writeln!(out, "}}")?;
     writeln!(out)?;
@@ -126,15 +126,15 @@ fn write_host_rs(mut out: File, triple: Triple) -> io::Result<()> {
         "    /// Return the operating system for the current host."
     )?;
     writeln!(out, "    pub const fn host() -> Self {{")?;
-    writeln!(out, "        Self::{:?}", triple.operating_system)?;
+    writeln!(out, "        OperatingSystem::{:?}", triple.operating_system)?;
     writeln!(out, "    }}")?;
     writeln!(out, "}}")?;
     writeln!(out)?;
 
     writeln!(out, "impl Environment {{")?;
     writeln!(out, "    /// Return the environment for the current host.")?;
     writeln!(out, "    pub const fn host() -> Self {{")?;
-    writeln!(out, "        Self::{:?}", triple.environment)?;
+    writeln!(out, "        Environment::{:?}", triple.environment)?;
     writeln!(out, "    }}")?;
     writeln!(out, "}}")?;
     writeln!(out)?;
@@ -145,7 +145,7 @@ fn write_host_rs(mut out: File, triple: Triple) -> io::Result<()> {
         "    /// Return the binary format for the current host."
     )?;
     writeln!(out, "    pub const fn host() -> Self {{")?;
-    writeln!(out, "        Self::{:?}", triple.binary_format)?;
+    writeln!(out, "        BinaryFormat::{:?}", triple.binary_format)?;
     writeln!(out, "    }}")?;
     writeln!(out, "}}")?;
     writeln!(out)?;

src/data_model.rs

@@ -40,7 +40,7 @@ impl Size {
 ///
 /// See also https://en.cppreference.com/w/c/language/arithmetic_types
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 pub enum CDataModel {
     /// The data model used most commonly on Win16. `long` and `pointer` are 32 bits.
     LP32,

src/lib.rs

@@ -15,8 +15,11 @@
         clippy::use_self,
     )
 )]
-#![cfg_attr(not(feature = "std"), no_std)]
 
+#![cfg_attr(not(feature = "std"), no_std)]
+#[cfg(feature = "std")]
+extern crate std as alloc;
+#[cfg(not(feature = "std"))]
 extern crate alloc;
 
 mod data_model;

src/targets.rs

@@ -9,7 +9,7 @@ use core::str::FromStr;
 
 /// The "architecture" field, which in some cases also specifies a specific
 /// subarchitecture.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Architecture {
@@ -38,7 +38,7 @@ pub enum Architecture {
     X86_64,
 }
 
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum ArmArchitecture {
@@ -85,15 +85,15 @@ pub enum ArmArchitecture {
     Thumbv8mMain,
 }
 
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Aarch64Architecture {
     Aarch64,
     Aarch64be,
 }
 
-// #[non_exhaustive]
+// #[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 // #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 // #[allow(missing_docs)]
 // pub enum ArmFpu {
@@ -290,7 +290,7 @@ impl Aarch64Architecture {
 }
 
 /// An enum for all 32-bit RISC-V architectures.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Riscv32Architecture {
@@ -301,7 +301,7 @@ pub enum Riscv32Architecture {
 }
 
 /// An enum for all 64-bit RISC-V architectures.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Riscv64Architecture {
@@ -311,7 +311,7 @@ pub enum Riscv64Architecture {
 }
 
 /// An enum for all 32-bit x86 architectures.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum X86_32Architecture {
@@ -321,7 +321,7 @@ pub enum X86_32Architecture {
 }
 
 /// An enum for all 32-bit MIPS architectures (not just "MIPS32").
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Mips32Architecture {
@@ -332,7 +332,7 @@ pub enum Mips32Architecture {
 }
 
 /// An enum for all 64-bit MIPS architectures (not just "MIPS64").
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Mips64Architecture {
@@ -377,7 +377,7 @@ impl Hash for CustomVendor {
 
 /// The "vendor" field, which in practice is little more than an arbitrary
 /// modifier.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Vendor {
@@ -405,7 +405,7 @@ pub enum Vendor {
 
 /// The "operating system" field, which sometimes implies an environment, and
 /// sometimes isn't an actual operating system.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum OperatingSystem {
@@ -442,7 +442,7 @@ pub enum OperatingSystem {
 /// The "environment" field, which specifies an ABI environment on top of the
 /// operating system. In many configurations, this field is omitted, and the
 /// environment is implied by the operating system.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum Environment {
@@ -473,7 +473,7 @@ pub enum Environment {
 
 /// The "binary format" field, which is usually omitted, and the binary format
 /// is implied by the other fields.
-#[non_exhaustive]
+#[cfg_attr(feature = "rust_1_40", non_exhaustive)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 #[allow(missing_docs)]
 pub enum BinaryFormat {