Revert "address pr review comments"

This reverts commit 05bf037.

Author: pnkfelix

compiler/rustc_middle/src/ty/layout.rs

@@ -2595,25 +2595,7 @@ fn fn_can_unwind(
                 C { unwind } | Stdcall { unwind } | System { unwind } | Thiscall { unwind } => {
                     unwind
                 }
-                Cdecl
-                | Fastcall
-                | Vectorcall
-                | Aapcs
-                | Win64
-                | SysV64
-                | PtxKernel
-                | Msp430Interrupt
-                | X86Interrupt
-                | AmdGpuKernel
-                | EfiApi
-                | AvrInterrupt
-                | AvrNonBlockingInterrupt
-                | CCmseNonSecureCall
-                | RustIntrinsic
-                | PlatformIntrinsic
-                | Unadjusted => false,
-                // In the `if` above, we checked for functions with the Rust calling convention.
-                Rust | RustCall => unreachable!(),
+                _ => false,
             }
         }
     }

compiler/rustc_mir_build/src/build/mod.rs

@@ -590,23 +590,7 @@ fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: LocalDefId, abi: Abi) -> bo
                 // Rust and `rust-call` functions are allowed to unwind, and should not abort.
                 Rust | RustCall => false,
                 // Other ABI's should abort.
-                Cdecl
-                | Fastcall
-                | Vectorcall
-                | Aapcs
-                | Win64
-                | SysV64
-                | PtxKernel
-                | Msp430Interrupt
-                | X86Interrupt
-                | AmdGpuKernel
-                | EfiApi
-                | AvrInterrupt
-                | AvrNonBlockingInterrupt
-                | CCmseNonSecureCall
-                | RustIntrinsic
-                | PlatformIntrinsic
-                | Unadjusted => true,
+                _ => true,
             }
         }
     }

compiler/rustc_target/src/spec/abi.rs

@@ -107,7 +107,7 @@ impl Abi {
         // N.B., this ordering MUST match the AbiDatas array above.
         // (This is ensured by the test indices_are_correct().)
         use Abi::*;
-        let i = match self {
+        match self {
             // Cross-platform ABIs
             Rust => 0,
             C { unwind: false } => 1,
@@ -138,18 +138,7 @@ impl Abi {
             RustCall => 24,
             PlatformIntrinsic => 25,
             Unadjusted => 26,
-        };
-        debug_assert!(
-            AbiDatas
-                .iter()
-                .enumerate()
-                .find(|(_, AbiData { abi, .. })| *abi == self)
-                .map(|(index, _)| index)
-                .expect("abi variant has associated data")
-                == i,
-            "Abi index did not match `AbiDatas` ordering"
-        );
-        i
+        }
     }
 
     #[inline]

src/doc/unstable-book/src/language-features/c-unwind.md

@@ -6,8 +6,7 @@ The tracking issue for this feature is: [#74990]
 
 ------------------------
 
-Introduces four new ABI strings: "C-unwind", "stdcall-unwind",
-"thiscall-unwind", and "system-unwind". These enable unwinding from other
+Introduces a new ABI string, "C-unwind", to enable unwinding from other
 languages (such as C++) into Rust frames and from Rust into other languages.
 
 See [RFC 2945] for more information.