Parse target_abi if it's present even though it's unstable

Author: carols10cents

src/expr.rs

@@ -30,6 +30,8 @@ use crate::targets as targ;
 /// All predicates that pertains to a target, except for `target_feature`
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub enum TargetPredicate {
+    /// [target_abi](https://github.com/rust-lang/rust/issues/80970)
+    Abi(targ::Abi),
     /// [target_arch](https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch)
     Arch(targ::Arch),
     /// [target_endian](https://doc.rust-lang.org/reference/conditional-compilation.html#target_endian)
@@ -59,10 +61,15 @@ pub trait TargetMatcher {
 impl TargetMatcher for targ::TargetInfo {
     fn matches(&self, tp: &TargetPredicate) -> bool {
         use TargetPredicate::{
-            Arch, Endian, Env, Family, HasAtomic, Os, Panic, PointerWidth, Vendor,
+            Abi, Arch, Endian, Env, Family, HasAtomic, Os, Panic, PointerWidth, Vendor,
         };
 
         match tp {
+            // The ABI is allowed to be an empty string
+            Abi(abi) => match &self.abi {
+                Some(a) => abi == a,
+                None => abi.0.is_empty(),
+            },
             Arch(a) => a == &self.arch,
             Endian(end) => *end == self.endian,
             // The environment is allowed to be an empty string
@@ -90,10 +97,14 @@ impl TargetMatcher for target_lexicon::Triple {
     fn matches(&self, tp: &TargetPredicate) -> bool {
         use target_lexicon::*;
         use TargetPredicate::{
-            Arch, Endian, Env, Family, HasAtomic, Os, Panic, PointerWidth, Vendor,
+            Abi, Arch, Endian, Env, Family, HasAtomic, Os, Panic, PointerWidth, Vendor,
         };
 
         match tp {
+            Abi(_) => {
+                // `target_abi` is unstable. Assume false for this.
+                false
+            }
             Arch(arch) => {
                 if arch == &targ::Arch::x86 {
                     matches!(self.architecture, Architecture::X86_32(_))
@@ -356,6 +367,7 @@ impl TargetPredicate {
 
 #[derive(Clone, Debug)]
 pub(crate) enum Which {
+    Abi,
     Arch,
     Endian(targ::Endian),
     Env,
@@ -419,6 +431,9 @@ impl InnerPredicate {
 
         match self {
             IP::Target(it) => match &it.which {
+                Which::Abi => Target(TargetPredicate::Abi(targ::Abi::new(
+                    s[it.span.clone().unwrap()].to_owned(),
+                ))),
                 Which::Arch => Target(TargetPredicate::Arch(targ::Arch::new(
                     s[it.span.clone().unwrap()].to_owned(),
                 ))),

src/expr/parser.rs

@@ -144,6 +144,7 @@ impl Expression {
                     }
 
                     let tp = match &target_key[7..] {
+                        "abi" => tp!(Abi),
                         "arch" => tp!(Arch),
                         "feature" => {
                             if val.is_empty() {

src/targets.rs

@@ -11,6 +11,10 @@ pub use builtins::ALL_BUILTINS;
 #[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct Triple(pub Cow<'static, str>);
 
+/// The "abi" field
+#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
+pub struct Abi(pub Cow<'static, str>);
+
 /// The "architecture" field
 #[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 pub struct Arch(pub Cow<'static, str>);
@@ -79,6 +83,7 @@ macro_rules! field_impls {
 }
 
 field_impls!(Triple);
+field_impls!(Abi);
 field_impls!(Arch);
 field_impls!(Vendor);
 field_impls!(Os);
@@ -316,6 +321,9 @@ pub struct TargetInfo {
     /// [target_os](https://doc.rust-lang.org/reference/conditional-compilation.html#target_os)
     /// predicate.
     pub os: Option<Os>,
+    /// The target's ABI, if any. Used by the
+    /// [target_abi](https://github.com/rust-lang/rust/issues/80970) predicate.
+    pub abi: Option<Abi>,
     /// The target's CPU architecture. Used by the
     /// [target_arch](https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch)
     /// predicate.