Introduce a op module with struct representations of each routine

This contains:

1. Per-function and per-operation enums created by the proc macro
2. The `MathOp` trait which is implemented once per struct representing
   a function
3. Submodules for each function, each containing a `Routine` struct that
   implements `MathOp`

library/compiler-builtins/libm/crates/libm-test/src/lib.rs

@@ -1,10 +1,12 @@
 pub mod gen;
 #[cfg(feature = "test-multiprecision")]
 pub mod mpfloat;
+pub mod op;
 mod precision;
 mod test_traits;
 
 pub use libm::support::{Float, Int};
+pub use op::{BaseName, MathOp, Name};
 pub use precision::{MaybeOverride, SpecialCase, multiprec_allowed_ulp, musl_allowed_ulp};
 pub use test_traits::{CheckBasis, CheckCtx, CheckOutput, GenerateInput, Hex, TupleCall};
 

library/compiler-builtins/libm/crates/libm-test/src/op.rs

@@ -0,0 +1,111 @@
+//! Types representing individual functions.
+//!
+//! Each routine gets a module with its name, e.g. `mod sinf { /* ... */ }`. The module
+//! contains a unit struct `Routine` which implements `MathOp`.
+//!
+//! Basically everything could be called a "function" here, so we loosely use the following
+//! terminology:
+//!
+//! - "Function": the math operation that does not have an associated precision. E.g. `f(x) = e^x`,
+//!   `f(x) = log(x)`.
+//! - "Routine": A code implementation of a math operation with a specific precision. E.g. `exp`,
+//!   `expf`, `expl`, `log`, `logf`.
+//! - "Operation" / "Op": Something that relates a routine to a function or is otherwise higher
+//!   level. `Op` is also used as the name for generic parameters since it is terse.
+
+use crate::{CheckOutput, Float, TupleCall};
+
+/// An enum representing each possible routine name.
+#[libm_macros::function_enum(BaseName)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum Name {}
+
+/// The name without any type specifier, e.g. `sin` and `sinf` both become `sin`.
+#[libm_macros::base_name_enum]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum BaseName {}
+
+/// Attributes ascribed to a `libm` routine including signature, type information,
+/// and naming.
+pub trait MathOp {
+    /// The float type used for this operation.
+    type FTy: Float;
+
+    /// The function type representing the signature in a C library.
+    type CFn: Copy;
+
+    /// Arguments passed to the C library function as a tuple. These may include `&mut` return
+    /// values.
+    type CArgs<'a>
+    where
+        Self: 'a;
+
+    /// The type returned by C implementations.
+    type CRet;
+
+    /// The signature of the Rust function as a `fn(...) -> ...` type.
+    type RustFn: Copy;
+
+    /// Arguments passed to the Rust library function as a tuple.
+    ///
+    /// The required `TupleCall` bounds ensure this type can be passed either to the C function or
+    /// to the Rust function.
+    type RustArgs: Copy
+        + TupleCall<Self::RustFn, Output = Self::RustRet>
+        + TupleCall<Self::CFn, Output = Self::RustRet>;
+
+    /// Type returned from the Rust function.
+    type RustRet: CheckOutput<Self::RustArgs>;
+
+    /// The name of this function, including suffix (e.g. `sin`, `sinf`).
+    const NAME: Name;
+
+    /// The name as a string.
+    const NAME_STR: &'static str = Self::NAME.as_str();
+
+    /// The name of the function excluding the type suffix, e.g. `sin` and `sinf` are both `sin`.
+    const BASE_NAME: BaseName = Self::NAME.base_name();
+
+    /// The function in `libm` which can be called.
+    const ROUTINE: Self::RustFn;
+}
+
+macro_rules! do_thing {
+    // Matcher for unary functions
+    (
+        fn_name: $fn_name:ident,
+        FTy: $FTy:ty,
+        CFn: $CFn:ty,
+        CArgs: $CArgs:ty,
+        CRet: $CRet:ty,
+        RustFn: $RustFn:ty,
+        RustArgs: $RustArgs:ty,
+        RustRet: $RustRet:ty,
+    ) => {
+        paste::paste! {
+            pub mod $fn_name {
+                use super::*;
+                pub struct Routine;
+
+                impl MathOp for Routine {
+                    type FTy = $FTy;
+                    type CFn = for<'a> $CFn;
+                    type CArgs<'a> = $CArgs where Self: 'a;
+                    type CRet = $CRet;
+                    type RustFn = $RustFn;
+                    type RustArgs = $RustArgs;
+                    type RustRet = $RustRet;
+
+                    const NAME: Name = Name::[< $fn_name:camel >];
+                    const ROUTINE: Self::RustFn = libm::$fn_name;
+                }
+            }
+
+        }
+    };
+}
+
+libm_macros::for_each_function! {
+    callback: do_thing,
+    emit_types: all,
+}

library/compiler-builtins/libm/crates/libm-test/src/test_traits.rs

@@ -137,7 +137,7 @@ where
     }
 }
 
-impl<T1, T2, T3> TupleCall<fn(T1, &mut T2, &mut T3)> for (T1,)
+impl<T1, T2, T3> TupleCall<for<'a> fn(T1, &'a mut T2, &'a mut T3)> for (T1,)
 where
     T1: fmt::Debug,
     T2: fmt::Debug + Default,
@@ -145,7 +145,7 @@ where
 {
     type Output = (T2, T3);
 
-    fn call(self, f: fn(T1, &mut T2, &mut T3)) -> Self::Output {
+    fn call(self, f: for<'a> fn(T1, &'a mut T2, &'a mut T3)) -> Self::Output {
         let mut t2 = T2::default();
         let mut t3 = T3::default();
         f(self.0, &mut t2, &mut t3);