special case TyAndLayout debug impl

compiler/rustc_target/src/abi/call/mod.rs

@@ -2,6 +2,7 @@ use crate::abi::{self, Abi, Align, FieldsShape, Size};
 use crate::abi::{HasDataLayout, TyAbiInterface, TyAndLayout};
 use crate::spec::{self, HasTargetSpec};
 use rustc_span::Symbol;
+use std::fmt;
 use std::str::FromStr;
 
 mod aarch64;
@@ -515,12 +516,20 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
 
 /// Information about how to pass an argument to,
 /// or return a value from, a function, under some ABI.
-#[derive(Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
+#[derive(Clone, PartialEq, Eq, Hash, HashStable_Generic)]
 pub struct ArgAbi<'a, Ty> {
     pub layout: TyAndLayout<'a, Ty>,
     pub mode: PassMode,
 }
 
+// Needs to be a custom impl because of the bounds on the `TyAndLayout` debug impl.
+impl<'a, Ty: fmt::Display> fmt::Debug for ArgAbi<'a, Ty> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let ArgAbi { layout, mode } = self;
+        f.debug_struct("ArgAbi").field("layout", layout).field("mode", mode).finish()
+    }
+}
+
 impl<'a, Ty> ArgAbi<'a, Ty> {
     /// This defines the "default ABI" for that type, that is then later adjusted in `fn_abi_adjust_for_abi`.
     pub fn new(
@@ -694,7 +703,7 @@ impl RiscvInterruptKind {
 ///
 /// I will do my best to describe this structure, but these
 /// comments are reverse-engineered and may be inaccurate. -NDM
-#[derive(Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
+#[derive(Clone, PartialEq, Eq, Hash, HashStable_Generic)]
 pub struct FnAbi<'a, Ty> {
     /// The LLVM types of each argument.
     pub args: Box<[ArgAbi<'a, Ty>]>,
@@ -715,6 +724,21 @@ pub struct FnAbi<'a, Ty> {
     pub can_unwind: bool,
 }
 
+// Needs to be a custom impl because of the bounds on the `TyAndLayout` debug impl.
+impl<'a, Ty: fmt::Display> fmt::Debug for FnAbi<'a, Ty> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let FnAbi { args, ret, c_variadic, fixed_count, conv, can_unwind } = self;
+        f.debug_struct("FnAbi")
+            .field("args", args)
+            .field("ret", ret)
+            .field("c_variadic", c_variadic)
+            .field("fixed_count", fixed_count)
+            .field("conv", conv)
+            .field("can_unwind", can_unwind)
+            .finish()
+    }
+}
+
 /// Error produced by attempting to adjust a `FnAbi`, for a "foreign" ABI.
 #[derive(Copy, Clone, Debug, HashStable_Generic)]
 pub enum AdjustForForeignAbiError {

compiler/rustc_target/src/abi/mod.rs

@@ -3,6 +3,7 @@ pub use Primitive::*;
 
 use crate::json::{Json, ToJson};
 
+use std::fmt;
 use std::ops::Deref;
 
 use rustc_macros::HashStable_Generic;
@@ -24,12 +25,22 @@ impl ToJson for Endian {
 /// to that obtained from `layout_of(ty)`, as we need to produce
 /// layouts for which Rust types do not exist, such as enum variants
 /// or synthetic fields of enums (i.e., discriminants) and fat pointers.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable_Generic)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
 pub struct TyAndLayout<'a, Ty> {
     pub ty: Ty,
     pub layout: Layout<'a>,
 }
 
+impl<'a, Ty: fmt::Display> fmt::Debug for TyAndLayout<'a, Ty> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Print the type in a readable way, not its debug representation.
+        f.debug_struct("TyAndLayout")
+            .field("ty", &format_args!("{}", self.ty))
+            .field("layout", &self.layout)
+            .finish()
+    }
+}
+
 impl<'a, Ty> Deref for TyAndLayout<'a, Ty> {
     type Target = &'a LayoutS;
     fn deref(&self) -> &&'a LayoutS {