Support functions that don't return

.github/workflows/test.yml

@@ -78,6 +78,7 @@ jobs:
         cargo test --target ${{ matrix.target }} -p test_core &&
         cargo test --target ${{ matrix.target }} -p test_debug &&
         cargo test --target ${{ matrix.target }} -p test_deprecated &&
+        cargo test --target ${{ matrix.target }} -p test_does_not_return &&
         cargo test --target ${{ matrix.target }} -p test_enums &&
         cargo test --target ${{ matrix.target }} -p test_handles &&
         cargo test --target ${{ matrix.target }} -p test_helpers &&
@@ -176,6 +177,7 @@ jobs:
         cargo clippy -p test_core &&
         cargo clippy -p test_debug &&
         cargo clippy -p test_deprecated &&
+        cargo clippy -p test_does_not_return &&
         cargo clippy -p test_enums &&
         cargo clippy -p test_handles &&
         cargo clippy -p test_helpers &&

crates/libs/bindgen/src/functions.rs

@@ -53,8 +53,12 @@ fn gen_function_if(entry: &[ElementType], gen: &Gen) -> TokenStream {
 fn gen_sys_function(def: &MethodDef, gen: &Gen) -> TokenStream {
     let name = gen_ident(def.name());
     let signature = def.signature(&[]);
-    let return_type = gen_return_sig(&signature, gen);
     let cfg = gen.function_cfg(def).gen_with_doc(gen);
+    let mut return_type = gen_return_sig(&signature, gen);
+
+    if return_type.is_empty() {
+        return_type = does_not_return(def);
+    }
 
     let params = signature.params.iter().map(|p| {
         let name = gen_param_name(&p.param);
@@ -214,16 +218,17 @@ fn gen_win_function(def: &MethodDef, gen: &Gen) -> TokenStream {
         SignatureKind::ReturnVoid => {
             let params = gen_win32_params(&signature.params, gen);
             let args = signature.params.iter().map(gen_win32_abi_arg);
+            let does_not_return = does_not_return(def);
 
             quote! {
                 #cfg
                 #[inline]
-                pub unsafe fn #name<#constraints>(#params) {
+                pub unsafe fn #name<#constraints>(#params) #does_not_return {
                     #[cfg(windows)]
                     {
                         #link_attr
                         extern "system" {
-                            fn #name(#(#abi_params),*);
+                            fn #name(#(#abi_params),*) #does_not_return;
                         }
                         #name(#(#args),*)
                     }
@@ -234,3 +239,11 @@ fn gen_win_function(def: &MethodDef, gen: &Gen) -> TokenStream {
         }
     }
 }
+
+fn does_not_return(def: &MethodDef) -> TokenStream {
+    if def.does_not_return() {
+        quote! { -> ! }
+    } else {
+        quote! {}
+    }
+}

crates/libs/metadata/src/tables/method_def.rs

@@ -69,6 +69,10 @@ impl MethodDef {
         self.has_attribute("DeprecatedAttribute")
     }
 
+    pub fn does_not_return(&self) -> bool {
+        self.has_attribute("DoesNotReturnAttribute")
+    }
+
     pub fn static_lib(&self) -> Option<String> {
         self.attributes()
             .filter_map(|attribute| match attribute.name() {

crates/libs/sys/src/Windows/Win32/System/Diagnostics/Debug/mod.rs

@@ -110,7 +110,7 @@ extern "system" {
     #[cfg(feature = "Win32_Foundation")]
     pub fn FatalAppExitW(uaction: u32, lpmessagetext: super::super::super::Foundation::PWSTR);
     #[doc = "*Required features: 'Win32_System_Diagnostics_Debug'*"]
-    pub fn FatalExit(exitcode: i32);
+    pub fn FatalExit(exitcode: i32) -> !;
     #[doc = "*Required features: 'Win32_System_Diagnostics_Debug', 'Win32_Foundation'*"]
     #[cfg(feature = "Win32_Foundation")]
     pub fn FindDebugInfoFile(filename: super::super::super::Foundation::PSTR, symbolpath: super::super::super::Foundation::PSTR, debugfilepath: super::super::super::Foundation::PSTR) -> super::super::super::Foundation::HANDLE;
@@ -276,7 +276,7 @@ extern "system" {
     #[cfg(feature = "Win32_Foundation")]
     pub fn OutputDebugStringW(lpoutputstring: super::super::super::Foundation::PWSTR);
     #[doc = "*Required features: 'Win32_System_Diagnostics_Debug'*"]
-    pub fn RaiseException(dwexceptioncode: u32, dwexceptionflags: u32, nnumberofarguments: u32, lparguments: *const usize);
+    pub fn RaiseException(dwexceptioncode: u32, dwexceptionflags: u32, nnumberofarguments: u32, lparguments: *const usize) -> !;
     #[doc = "*Required features: 'Win32_System_Diagnostics_Debug', 'Win32_Foundation', 'Win32_System_Kernel'*"]
     #[cfg(all(feature = "Win32_Foundation", feature = "Win32_System_Kernel"))]
     pub fn RaiseFailFastException(pexceptionrecord: *const EXCEPTION_RECORD, pcontextrecord: *const CONTEXT, dwflags: u32);
@@ -368,7 +368,7 @@ extern "system" {
     pub fn RtlPcToFileHeader(pcvalue: *const ::core::ffi::c_void, baseofimage: *mut *mut ::core::ffi::c_void) -> *mut ::core::ffi::c_void;
     #[doc = "*Required features: 'Win32_System_Diagnostics_Debug', 'Win32_Foundation'*"]
     #[cfg(feature = "Win32_Foundation")]
-    pub fn RtlRaiseException(exceptionrecord: *const EXCEPTION_RECORD);
+    pub fn RtlRaiseException(exceptionrecord: *const EXCEPTION_RECORD) -> !;
     #[doc = "*Required features: 'Win32_System_Diagnostics_Debug', 'Win32_Foundation', 'Win32_System_Kernel'*"]
     #[cfg(all(feature = "Win32_Foundation", feature = "Win32_System_Kernel"))]
     pub fn RtlRestoreContext(contextrecord: *const CONTEXT, exceptionrecord: *const EXCEPTION_RECORD);

crates/libs/sys/src/Windows/Win32/System/LibraryLoader/mod.rs

@@ -72,7 +72,7 @@ extern "system" {
     pub fn FreeLibrary(hlibmodule: super::super::Foundation::HINSTANCE) -> super::super::Foundation::BOOL;
     #[doc = "*Required features: 'Win32_System_LibraryLoader', 'Win32_Foundation'*"]
     #[cfg(feature = "Win32_Foundation")]
-    pub fn FreeLibraryAndExitThread(hlibmodule: super::super::Foundation::HINSTANCE, dwexitcode: u32);
+    pub fn FreeLibraryAndExitThread(hlibmodule: super::super::Foundation::HINSTANCE, dwexitcode: u32) -> !;
     #[doc = "*Required features: 'Win32_System_LibraryLoader', 'Win32_Foundation'*"]
     #[cfg(feature = "Win32_Foundation")]
     pub fn FreeResource(hresdata: isize) -> super::super::Foundation::BOOL;

crates/libs/sys/src/Windows/Win32/System/Threading/mod.rs

@@ -247,9 +247,9 @@ extern "system" {
     #[cfg(feature = "Win32_Foundation")]
     pub fn ExecuteUmsThread(umsthread: *mut ::core::ffi::c_void) -> super::super::Foundation::BOOL;
     #[doc = "*Required features: 'Win32_System_Threading'*"]
-    pub fn ExitProcess(uexitcode: u32);
+    pub fn ExitProcess(uexitcode: u32) -> !;
     #[doc = "*Required features: 'Win32_System_Threading'*"]
-    pub fn ExitThread(dwexitcode: u32);
+    pub fn ExitThread(dwexitcode: u32) -> !;
     #[doc = "*Required features: 'Win32_System_Threading'*"]
     pub fn FlsAlloc(lpcallback: PFLS_CALLBACK_FUNCTION) -> u32;
     #[doc = "*Required features: 'Win32_System_Threading', 'Win32_Foundation'*"]

crates/libs/windows/src/Windows/Win32/System/Diagnostics/Debug/mod.rs

@@ -9147,12 +9147,12 @@ pub unsafe fn FatalAppExitW<'a, Param1: ::windows::core::IntoParam<'a, super::su
 }
 #[doc = "*Required features: 'Win32_System_Diagnostics_Debug'*"]
 #[inline]
-pub unsafe fn FatalExit(exitcode: i32) {
+pub unsafe fn FatalExit(exitcode: i32) -> ! {
     #[cfg(windows)]
     {
         #[link(name = "windows")]
         extern "system" {
-            fn FatalExit(exitcode: i32);
+            fn FatalExit(exitcode: i32) -> !;
         }
         FatalExit(::core::mem::transmute(exitcode))
     }
@@ -59972,12 +59972,12 @@ impl ::core::fmt::Debug for RTL_VIRTUAL_UNWIND_HANDLER_TYPE {
 }
 #[doc = "*Required features: 'Win32_System_Diagnostics_Debug'*"]
 #[inline]
-pub unsafe fn RaiseException(dwexceptioncode: u32, dwexceptionflags: u32, nnumberofarguments: u32, lparguments: *const usize) {
+pub unsafe fn RaiseException(dwexceptioncode: u32, dwexceptionflags: u32, nnumberofarguments: u32, lparguments: *const usize) -> ! {
     #[cfg(windows)]
     {
         #[link(name = "windows")]
         extern "system" {
-            fn RaiseException(dwexceptioncode: u32, dwexceptionflags: u32, nnumberofarguments: u32, lparguments: *const usize);
+            fn RaiseException(dwexceptioncode: u32, dwexceptionflags: u32, nnumberofarguments: u32, lparguments: *const usize) -> !;
         }
         RaiseException(::core::mem::transmute(dwexceptioncode), ::core::mem::transmute(dwexceptionflags), ::core::mem::transmute(nnumberofarguments), ::core::mem::transmute(lparguments))
     }
@@ -60463,12 +60463,12 @@ pub unsafe fn RtlPcToFileHeader(pcvalue: *const ::core::ffi::c_void, baseofimage
 #[doc = "*Required features: 'Win32_System_Diagnostics_Debug', 'Win32_Foundation'*"]
 #[cfg(feature = "Win32_Foundation")]
 #[inline]
-pub unsafe fn RtlRaiseException(exceptionrecord: *const EXCEPTION_RECORD) {
+pub unsafe fn RtlRaiseException(exceptionrecord: *const EXCEPTION_RECORD) -> ! {
     #[cfg(windows)]
     {
         #[link(name = "windows")]
         extern "system" {
-            fn RtlRaiseException(exceptionrecord: *const EXCEPTION_RECORD);
+            fn RtlRaiseException(exceptionrecord: *const EXCEPTION_RECORD) -> !;
         }
         RtlRaiseException(::core::mem::transmute(exceptionrecord))
     }

crates/libs/windows/src/Windows/Win32/System/LibraryLoader/mod.rs

@@ -405,12 +405,12 @@ pub unsafe fn FreeLibrary<'a, Param0: ::windows::core::IntoParam<'a, super::supe
 #[doc = "*Required features: 'Win32_System_LibraryLoader', 'Win32_Foundation'*"]
 #[cfg(feature = "Win32_Foundation")]
 #[inline]
-pub unsafe fn FreeLibraryAndExitThread<'a, Param0: ::windows::core::IntoParam<'a, super::super::Foundation::HINSTANCE>>(hlibmodule: Param0, dwexitcode: u32) {
+pub unsafe fn FreeLibraryAndExitThread<'a, Param0: ::windows::core::IntoParam<'a, super::super::Foundation::HINSTANCE>>(hlibmodule: Param0, dwexitcode: u32) -> ! {
     #[cfg(windows)]
     {
         #[link(name = "windows")]
         extern "system" {
-            fn FreeLibraryAndExitThread(hlibmodule: super::super::Foundation::HINSTANCE, dwexitcode: u32);
+            fn FreeLibraryAndExitThread(hlibmodule: super::super::Foundation::HINSTANCE, dwexitcode: u32) -> !;
         }
         FreeLibraryAndExitThread(hlibmodule.into_param().abi(), ::core::mem::transmute(dwexitcode))
     }

crates/libs/windows/src/Windows/Win32/System/Threading/mod.rs

@@ -1540,12 +1540,12 @@ pub unsafe fn ExecuteUmsThread(umsthread: *mut ::core::ffi::c_void) -> super::su
 }
 #[doc = "*Required features: 'Win32_System_Threading'*"]
 #[inline]
-pub unsafe fn ExitProcess(uexitcode: u32) {
+pub unsafe fn ExitProcess(uexitcode: u32) -> ! {
     #[cfg(windows)]
     {
         #[link(name = "windows")]
         extern "system" {
-            fn ExitProcess(uexitcode: u32);
+            fn ExitProcess(uexitcode: u32) -> !;
         }
         ExitProcess(::core::mem::transmute(uexitcode))
     }
@@ -1554,12 +1554,12 @@ pub unsafe fn ExitProcess(uexitcode: u32) {
 }
 #[doc = "*Required features: 'Win32_System_Threading'*"]
 #[inline]
-pub unsafe fn ExitThread(dwexitcode: u32) {
+pub unsafe fn ExitThread(dwexitcode: u32) -> ! {
     #[cfg(windows)]
     {
         #[link(name = "windows")]
         extern "system" {
-            fn ExitThread(dwexitcode: u32);
+            fn ExitThread(dwexitcode: u32) -> !;
         }
         ExitThread(::core::mem::transmute(dwexitcode))
     }

crates/tests/does_not_return/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "test_does_not_return"
+version = "0.0.0"
+authors = ["Microsoft"]
+edition = "2018"
+
+[dependencies.windows]
+path = "../../libs/windows"
+features = [
+    "Win32_System_Diagnostics_Debug",
+]
+
+[dependencies.windows-sys]
+path = "../../libs/sys"
+features = [
+    "Win32_System_Diagnostics_Debug",
+]

crates/tests/does_not_return/src/lib.rs

@@ -0,0 +1 @@
+

crates/tests/does_not_return/tests/sys.rs

@@ -0,0 +1,10 @@
+use windows_sys::Win32::System::Diagnostics::Debug::FatalExit;
+
+// Compile-only test to check that FatalExit returns `-> !`
+
+#[allow(dead_code)]
+fn test() -> i32 {
+    unsafe {
+        FatalExit(123);
+    }
+}

crates/tests/does_not_return/tests/win.rs

@@ -0,0 +1,10 @@
+use windows::Win32::System::Diagnostics::Debug::FatalExit;
+
+// Compile-only test to check that FatalExit returns `-> !`
+
+#[allow(dead_code)]
+fn test() -> i32 {
+    unsafe {
+        FatalExit(123);
+    }
+}