make thiscall on unsupported platforms an error

compiler/rustc_target/src/spec/mod.rs

@@ -1522,6 +1522,7 @@ impl Target {
             AmdGpuKernel => self.arch == "amdgcn",
             AvrInterrupt | AvrNonBlockingInterrupt => self.arch == "avr",
             Wasm => ["wasm32", "wasm64"].contains(&&self.arch[..]),
+            Thiscall { .. } => self.arch == "x86",
             // On windows these fall-back to platform native calling convention (C) when the
             // architecture is not supported.
             //
@@ -1552,15 +1553,13 @@ impl Target {
             // > convention is used.
             //
             // -- https://docs.microsoft.com/en-us/cpp/cpp/argument-passing-and-naming-conventions
-            Stdcall { .. } | Fastcall | Thiscall { .. } | Vectorcall if self.is_like_windows => {
+            Stdcall { .. } | Fastcall | Vectorcall if self.is_like_windows => true,
-                true
-            }
             // Outside of Windows we want to only support these calling conventions for the
             // architectures for which these calling conventions are actually well defined.
-            Stdcall { .. } | Fastcall | Thiscall { .. } if self.arch == "x86" => true,
+            Stdcall { .. } | Fastcall if self.arch == "x86" => true,
             Vectorcall if ["x86", "x86_64"].contains(&&self.arch[..]) => true,
             // Return a `None` for other cases so that we know to emit a future compat lint.
-            Stdcall { .. } | Fastcall | Thiscall { .. } | Vectorcall => return None,
+            Stdcall { .. } | Fastcall | Vectorcall => return None,
         })
     }
 

src/test/ui/abi/unsupported.aarch64.stderr

@@ -40,9 +40,15 @@ error[E0570]: `"x86-interrupt"` is not a supported ABI for the current target
 LL | extern "x86-interrupt" fn x86() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"thiscall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:43:1
    |
+LL | extern "thiscall" fn thiscall() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: use of calling convention not supported on this target
+  --> $DIR/unsupported.rs:47:1
+   |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
@@ -50,15 +56,6 @@ LL | extern "stdcall" fn stdcall() {}
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
 
-warning: use of calling convention not supported on this target
+error: aborting due to 8 previous errors; 1 warning emitted
-  --> $DIR/unsupported.rs:50:1
-   |
-LL | extern "thiscall" fn thiscall() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
-
-error: aborting due to 7 previous errors; 2 warnings emitted
 
 For more information about this error, try `rustc --explain E0570`.

src/test/ui/abi/unsupported.arm.stderr

@@ -34,9 +34,15 @@ error[E0570]: `"x86-interrupt"` is not a supported ABI for the current target
 LL | extern "x86-interrupt" fn x86() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"thiscall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:43:1
    |
+LL | extern "thiscall" fn thiscall() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: use of calling convention not supported on this target
+  --> $DIR/unsupported.rs:47:1
+   |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
@@ -44,15 +50,6 @@ LL | extern "stdcall" fn stdcall() {}
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
 
-warning: use of calling convention not supported on this target
+error: aborting due to 7 previous errors; 1 warning emitted
-  --> $DIR/unsupported.rs:50:1
-   |
-LL | extern "thiscall" fn thiscall() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
-
-error: aborting due to 6 previous errors; 2 warnings emitted
 
 For more information about this error, try `rustc --explain E0570`.

src/test/ui/abi/unsupported.rs

@@ -40,6 +40,10 @@ extern "avr-interrupt" fn avr() {}
 extern "x86-interrupt" fn x86() {}
 //[aarch64]~^ ERROR is not a supported ABI
 //[arm]~^^ ERROR is not a supported ABI
+extern "thiscall" fn thiscall() {}
+//[x64]~^ ERROR is not a supported ABI
+//[aarch64]~^^ ERROR is not a supported ABI
+//[arm]~^^^ ERROR is not a supported ABI
 extern "stdcall" fn stdcall() {}
 //[x64]~^ WARN use of calling convention not supported
 //[x64]~^^ WARN this was previously accepted
@@ -47,10 +51,3 @@ extern "stdcall" fn stdcall() {}
 //[aarch64]~^^^^ WARN this was previously accepted
 //[arm]~^^^^^ WARN use of calling convention not supported
 //[arm]~^^^^^^ WARN this was previously accepted
-extern "thiscall" fn thiscall() {}
-//[x64]~^ WARN use of calling convention not supported
-//[x64]~^^ WARN this was previously accepted
-//[aarch64]~^^^ WARN use of calling convention not supported
-//[aarch64]~^^^^ WARN this was previously accepted
-//[arm]~^^^^^ WARN use of calling convention not supported
-//[arm]~^^^^^^ WARN this was previously accepted

src/test/ui/abi/unsupported.x64.stderr

@@ -34,9 +34,15 @@ error[E0570]: `"avr-interrupt"` is not a supported ABI for the current target
 LL | extern "avr-interrupt" fn avr() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: use of calling convention not supported on this target
+error[E0570]: `"thiscall"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:43:1
    |
+LL | extern "thiscall" fn thiscall() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: use of calling convention not supported on this target
+  --> $DIR/unsupported.rs:47:1
+   |
 LL | extern "stdcall" fn stdcall() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
@@ -44,15 +50,6 @@ LL | extern "stdcall" fn stdcall() {}
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
 
-warning: use of calling convention not supported on this target
+error: aborting due to 7 previous errors; 1 warning emitted
-  --> $DIR/unsupported.rs:50:1
-   |
-LL | extern "thiscall" fn thiscall() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
-
-error: aborting due to 6 previous errors; 2 warnings emitted
 
 For more information about this error, try `rustc --explain E0570`.