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Fix: emit extern "C" fn for functions declared in extern "C" blocks #4210

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Merged
riverar merged 7 commits into from
Apr 18, 2026
Merged

Fix: emit extern "C" fn for functions declared in extern "C" blocks #4210

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4c618f7
Initial plan
Copilot Apr 18, 2026
d0ef72b
Fix: emit extern \"C\" fn for functions declared in extern \"C\" blocks
Copilot Apr 18, 2026
8cb2462
Fix: emit extern \"C\" fn for functions in extern \"C\" blocks (in cr…
Copilot Apr 18, 2026
091c2f0
Revert unrelated enum.rdl change to original i32 representation
Copilot Apr 18, 2026
23c710a
Fix rustfmt formatting in fn.rs and mod.rs
Copilot Apr 18, 2026
86aa084
Revert all changes to enum.rdl to original state
Copilot Apr 18, 2026
5e44a17
Merge branch 'master' into copilot/fix-extern-c-functions
kennykerr Apr 18, 2026
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5 changes: 5 additions & 0 deletions crates/tests/tools/header2rdl/tests/fn_extern_c.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
extern "C"
{
unsigned int GetTickCount();
void SetLastErrorEx(unsigned a, signed b);
}
2 changes: 2 additions & 0 deletions crates/tests/tools/header2rdl/tests/fn_extern_c.h.args
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@@ -0,0 +1,2 @@
--cpp
--library test.dll
7 changes: 7 additions & 0 deletions crates/tests/tools/header2rdl/tests/fn_extern_c.rdl
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@@ -0,0 +1,7 @@
#[win32]
mod Test {
#[library("test.dll")]
extern "C" fn GetTickCount() -> u32;
#[library("test.dll")]
extern "C" fn SetLastErrorEx(a: u32, b: i32);
}
42 changes: 21 additions & 21 deletions crates/tests/tools/header2rdl/tests/webview2.rdl
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Expand Up @@ -474,11 +474,11 @@ mod Test {
COREWEBVIEW2_WEB_RESOURCE_REQUEST_SOURCE_KINDS_ALL = -1,
}
#[library("WebView2")]
extern fn CompareBrowserVersions(version1: PCWSTR, version2: PCWSTR, result: *mut i32) -> HRESULT;
extern "C" fn CompareBrowserVersions(version1: PCWSTR, version2: PCWSTR, result: *mut i32) -> HRESULT;
#[library("WebView2")]
extern fn CreateCoreWebView2Environment(environmentCreatedHandler: ICoreWebView2CreateCoreWebView2EnvironmentCompletedHandler) -> HRESULT;
extern "C" fn CreateCoreWebView2Environment(environmentCreatedHandler: ICoreWebView2CreateCoreWebView2EnvironmentCompletedHandler) -> HRESULT;
#[library("WebView2")]
extern fn CreateCoreWebView2EnvironmentWithOptions(browserExecutableFolder: PCWSTR, userDataFolder: PCWSTR, environmentOptions: ICoreWebView2EnvironmentOptions, environmentCreatedHandler: ICoreWebView2CreateCoreWebView2EnvironmentCompletedHandler) -> HRESULT;
extern "C" fn CreateCoreWebView2EnvironmentWithOptions(browserExecutableFolder: PCWSTR, userDataFolder: PCWSTR, environmentOptions: ICoreWebView2EnvironmentOptions, environmentCreatedHandler: ICoreWebView2CreateCoreWebView2EnvironmentCompletedHandler) -> HRESULT;
#[typedef]
struct DOUBLE {
value: f64,
Expand All @@ -501,9 +501,9 @@ mod Test {
Data4: [u8; 8],
}
#[library("WebView2")]
extern fn GetAvailableCoreWebView2BrowserVersionString(browserExecutableFolder: PCWSTR, versionInfo: *mut LPWSTR) -> HRESULT;
extern "C" fn GetAvailableCoreWebView2BrowserVersionString(browserExecutableFolder: PCWSTR, versionInfo: *mut LPWSTR) -> HRESULT;
#[library("WebView2")]
extern fn GetAvailableCoreWebView2BrowserVersionStringWithOptions(browserExecutableFolder: PCWSTR, environmentOptions: ICoreWebView2EnvironmentOptions, versionInfo: *mut LPWSTR) -> HRESULT;
extern "C" fn GetAvailableCoreWebView2BrowserVersionStringWithOptions(browserExecutableFolder: PCWSTR, environmentOptions: ICoreWebView2EnvironmentOptions, versionInfo: *mut LPWSTR) -> HRESULT;
#[typedef]
struct HANDLE {
value: *mut u8,
Expand Down Expand Up @@ -2211,51 +2211,51 @@ mod Test {
fn ShowSaveAsUI(&self, handler: ICoreWebView2ShowSaveAsUICompletedHandler) -> HRESULT;
}
#[library("WebView2")]
extern fn ICoreWebView2_25_ShowSaveAsUI_Proxy(This: ICoreWebView2_25, handler: ICoreWebView2ShowSaveAsUICompletedHandler) -> HRESULT;
extern "C" fn ICoreWebView2_25_ShowSaveAsUI_Proxy(This: ICoreWebView2_25, handler: ICoreWebView2ShowSaveAsUICompletedHandler) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_25_ShowSaveAsUI_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_25_ShowSaveAsUI_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[library("WebView2")]
extern fn ICoreWebView2_25_add_SaveAsUIShowing_Proxy(This: ICoreWebView2_25, eventHandler: ICoreWebView2SaveAsUIShowingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
extern "C" fn ICoreWebView2_25_add_SaveAsUIShowing_Proxy(This: ICoreWebView2_25, eventHandler: ICoreWebView2SaveAsUIShowingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_25_add_SaveAsUIShowing_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_25_add_SaveAsUIShowing_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[library("WebView2")]
extern fn ICoreWebView2_25_remove_SaveAsUIShowing_Proxy(This: ICoreWebView2_25, token: EventRegistrationToken) -> HRESULT;
extern "C" fn ICoreWebView2_25_remove_SaveAsUIShowing_Proxy(This: ICoreWebView2_25, token: EventRegistrationToken) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_25_remove_SaveAsUIShowing_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_25_remove_SaveAsUIShowing_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[guid(0x806268b8_f897_5685_88e5_c45fca0b1a48)]
interface ICoreWebView2_26: ICoreWebView2_25 {
fn add_SaveFileSecurityCheckStarting(&self, eventHandler: ICoreWebView2SaveFileSecurityCheckStartingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
fn remove_SaveFileSecurityCheckStarting(&self, token: EventRegistrationToken) -> HRESULT;
}
#[library("WebView2")]
extern fn ICoreWebView2_26_add_SaveFileSecurityCheckStarting_Proxy(This: ICoreWebView2_26, eventHandler: ICoreWebView2SaveFileSecurityCheckStartingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
extern "C" fn ICoreWebView2_26_add_SaveFileSecurityCheckStarting_Proxy(This: ICoreWebView2_26, eventHandler: ICoreWebView2SaveFileSecurityCheckStartingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_26_add_SaveFileSecurityCheckStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_26_add_SaveFileSecurityCheckStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[library("WebView2")]
extern fn ICoreWebView2_26_remove_SaveFileSecurityCheckStarting_Proxy(This: ICoreWebView2_26, token: EventRegistrationToken) -> HRESULT;
extern "C" fn ICoreWebView2_26_remove_SaveFileSecurityCheckStarting_Proxy(This: ICoreWebView2_26, token: EventRegistrationToken) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_26_remove_SaveFileSecurityCheckStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_26_remove_SaveFileSecurityCheckStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[guid(0x00fbe33b_8c07_517c_aa23_0ddd4b5f6fa0)]
interface ICoreWebView2_27: ICoreWebView2_26 {
fn add_ScreenCaptureStarting(&self, eventHandler: ICoreWebView2ScreenCaptureStartingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
fn remove_ScreenCaptureStarting(&self, token: EventRegistrationToken) -> HRESULT;
}
#[library("WebView2")]
extern fn ICoreWebView2_27_add_ScreenCaptureStarting_Proxy(This: ICoreWebView2_27, eventHandler: ICoreWebView2ScreenCaptureStartingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
extern "C" fn ICoreWebView2_27_add_ScreenCaptureStarting_Proxy(This: ICoreWebView2_27, eventHandler: ICoreWebView2ScreenCaptureStartingEventHandler, token: *mut EventRegistrationToken) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_27_add_ScreenCaptureStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_27_add_ScreenCaptureStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[library("WebView2")]
extern fn ICoreWebView2_27_remove_ScreenCaptureStarting_Proxy(This: ICoreWebView2_27, token: EventRegistrationToken) -> HRESULT;
extern "C" fn ICoreWebView2_27_remove_ScreenCaptureStarting_Proxy(This: ICoreWebView2_27, token: EventRegistrationToken) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_27_remove_ScreenCaptureStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_27_remove_ScreenCaptureStarting_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[guid(0x62e50381_5bf5_51a8_aae0_f20a3a9c8a90)]
interface ICoreWebView2_28: ICoreWebView2_27 {
fn get_Find(&self, value: *mut ICoreWebView2Find) -> HRESULT;
}
#[library("WebView2")]
extern fn ICoreWebView2_28_get_Find_Proxy(This: ICoreWebView2_28, value: *mut ICoreWebView2Find) -> HRESULT;
extern "C" fn ICoreWebView2_28_get_Find_Proxy(This: ICoreWebView2_28, value: *mut ICoreWebView2Find) -> HRESULT;
#[library("WebView2")]
extern fn ICoreWebView2_28_get_Find_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
extern "C" fn ICoreWebView2_28_get_Find_Stub(This: *mut IRpcStubBuffer, _pRpcChannelBuffer: *mut IRpcChannelBuffer, _pRpcMessage: PRPC_MESSAGE, _pdwStubPhase: *mut DWORD);
#[guid(0xa0d6df20_3b92_416d_aa0c_437a9c727857)]
interface ICoreWebView2_3: ICoreWebView2_2 {
fn TrySuspend(&self, handler: ICoreWebView2TrySuspendCompletedHandler) -> HRESULT;
Expand Down
19 changes: 14 additions & 5 deletions crates/tools/header2rdl/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@
//! Requires `libclang` at build and run time. On Ubuntu 22.04+ set
//! `LIBCLANG_PATH=/usr/lib/llvm-20/lib` (or the installed LLVM version).

use clang::{diagnostic::Severity, Clang, Entity, EntityKind, Index, TypeKind};
use clang::{diagnostic::Severity, Clang, Entity, EntityKind, Index, Language, TypeKind};
use std::collections::BTreeSet;
use std::path::{Path, PathBuf};

Expand Down Expand Up @@ -344,6 +344,7 @@ struct RdlFn {
name: String,
params: Vec<(String, String)>,
ret: String,
extern_c: bool,
}

struct RdlInterface {
Expand Down Expand Up @@ -451,7 +452,12 @@ fn collect(entity: Entity, collector: &mut Collector) {
}
if let Some(name) = child.get_name() {
if collector.seen.insert(name.clone()) {
if let Some(f) = collect_function(&child, name) {
// In C++ mode, a function declared inside `extern "C" { }`
// has Language::C linkage. Track this so we can emit the
// correct `extern "C" fn` ABI in the RDL.
let extern_c = collector.cpp
&& child.get_language() == Some(Language::C);
if let Some(f) = collect_function(&child, name, extern_c) {
collector.functions.push(f);
}
}
Expand Down Expand Up @@ -668,7 +674,7 @@ fn collect_enum(entity: &Entity, name: String) -> Option<RdlEnum> {
})
}

fn collect_function(entity: &Entity, name: String) -> Option<RdlFn> {
fn collect_function(entity: &Entity, name: String, extern_c: bool) -> Option<RdlFn> {
let ty = entity.get_type()?;
let ret_ty = ty.get_result_type()?;
let ret = map_type(&ret_ty);
Expand All @@ -685,7 +691,7 @@ fn collect_function(entity: &Entity, name: String) -> Option<RdlFn> {
}
}

Some(RdlFn { name, params, ret })
Some(RdlFn { name, params, ret, extern_c })
}

fn collect_interface(entity: &Entity, name: String) -> Option<RdlInterface> {
Expand Down Expand Up @@ -747,6 +753,7 @@ fn collect_interface(entity: &Entity, name: String) -> Option<RdlInterface> {
name: mname,
params,
ret,
extern_c: false,
});
}

Expand Down Expand Up @@ -1020,7 +1027,9 @@ fn emit_fn(f: &RdlFn, library: &str) -> String {
format!("#[library(\"{library}\")] ")
};

format!("{lib_attr}extern fn {}({params}){ret};", f.name)
let abi = if f.extern_c { r#""C" "# } else { "" };

format!("{lib_attr}extern {abi}fn {}({params}){ret};", f.name)
}

fn emit_interface(iface: &RdlInterface) -> String {
Expand Down