transpile: Translate enums in switch as their own type instead of integers

Author: Rua

c2rust-ast-builder/src/builder.rs

@@ -1228,6 +1228,20 @@ impl Builder {
         })
     }
 
+    pub fn tuple_struct_pat<Pa>(self, path: Pa, qself: Option<QSelf>, elems: Vec<Pat>) -> Pat
+    where
+        Pa: Make<Path>,
+    {
+        let path = path.make(&self);
+        Pat::TupleStruct(PatTupleStruct {
+            attrs: self.attrs,
+            qself,
+            path,
+            paren_token: token::Paren(self.span),
+            elems: punct(elems),
+        })
+    }
+
     // Types
 
     pub fn barefn_ty(self, decl: BareFnTyParts) -> Box<Type> {

c2rust-transpile/src/cfg/mod.rs

@@ -433,7 +433,6 @@ impl GenTerminator<StructureLabel<StmtOrDecl>> {
 pub struct SwitchCases {
     cases: Vec<(Pat, Label)>,
     default: Option<Label>,
-    #[allow(unused)]
     override_type_id: Option<CQualTypeId>,
 }
 
@@ -1868,15 +1867,34 @@ impl CfgBuilder {
                 })?;
 
                 let expr = translator
-                    .convert_expr(ctx.const_().pattern().used(), case_expr, None)
+                    .convert_expr(
+                        ctx.const_().pattern().used(),
+                        case_expr,
+                        switch_case.override_type_id,
+                    )
                     .ok()
                     .and_then(WithStmts::to_pure_expr);
-                let pat = expr
-                    .and_then(|expr| expr_to_pat(*expr))
-                    .unwrap_or_else(|| match cie {
+                let pat = expr.and_then(|expr| expr_to_pat(*expr)).unwrap_or_else(|| {
+                    let mut pat = match cie {
                         ConstIntExpr::U(n) => mk().lit_pat(mk().int_unsuffixed_lit(n)),
                         ConstIntExpr::I(n) => mk().lit_pat(mk().int_unsuffixed_lit(n)),
-                    });
+                    };
+
+                    if let Some(override_ty) = switch_case.override_type_id {
+                        if let CTypeKind::Enum(enum_id) =
+                            translator.ast_context.resolve_type(override_ty.ctype).kind
+                        {
+                            let enum_name = translator
+                                .type_converter
+                                .borrow()
+                                .resolve_decl_name(enum_id)
+                                .unwrap();
+                            pat = mk().tuple_struct_pat(enum_name.as_str(), None, vec![pat]);
+                        }
+                    }
+
+                    pat
+                });
 
                 switch_case.cases.push((pat, this_label.clone()));
 
@@ -1947,7 +1965,7 @@ impl CfgBuilder {
                 }
 
                 let (stmts, val) = translator
-                    .convert_expr(ctx.used(), scrutinee, None)?
+                    .convert_expr(ctx.used(), scrutinee, override_type_id)?
                     .discard_unsafe();
                 wip.extend(stmts);
 

c2rust-transpile/tests/snapshots/snapshots__transpile@enums.c.2021.clang15.snap

@@ -49,10 +49,10 @@ pub unsafe extern "C" fn test_enums() {
         (e.0 == bar.0 as ::core::ffi::c_uint) as ::core::ffi::c_int;
     let mut wrong_enum_constant: ::core::ffi::c_int =
         (e.0 == Bar0.0 as ::core::ffi::c_uint) as ::core::ffi::c_int;
-    match foo.0 {
-        0 | FOO1_MACRO | 2 | 3 | 42 | 4294967254 | _ => {}
+    match foo {
+        Foo0 | Foo(FOO1_MACRO) | Foo2 | Foo(3) | Foo(42) | Foo(4294967254) | _ => {}
     }
-    match bar.0 {
-        0 | BAR1_MACRO | 2 | 3 | -1 | 42 | -42 | _ => {}
+    match bar {
+        Bar0 | Bar(BAR1_MACRO) | Bar2 | Bar(3) | BarN1 | Bar(42) | Bar(-42) | _ => {}
     };
 }

c2rust-transpile/tests/snapshots/snapshots__transpile@enums.c.2024.clang15.snap

@@ -50,10 +50,10 @@ pub unsafe extern "C" fn test_enums() {
         (e.0 == bar.0 as ::core::ffi::c_uint) as ::core::ffi::c_int;
     let mut wrong_enum_constant: ::core::ffi::c_int =
         (e.0 == Bar0.0 as ::core::ffi::c_uint) as ::core::ffi::c_int;
-    match foo.0 {
-        0 | FOO1_MACRO | 2 | 3 | 42 | 4294967254 | _ => {}
+    match foo {
+        Foo0 | Foo(FOO1_MACRO) | Foo2 | Foo(3) | Foo(42) | Foo(4294967254) | _ => {}
     }
-    match bar.0 {
-        0 | BAR1_MACRO | 2 | 3 | -1 | 42 | -42 | _ => {}
+    match bar {
+        Bar0 | Bar(BAR1_MACRO) | Bar2 | Bar(3) | BarN1 | Bar(42) | Bar(-42) | _ => {}
     };
 }

c2rust-transpile/tests/snapshots/snapshots__transpile@macrocase.c.2021.clang15.snap

@@ -20,12 +20,12 @@ pub const ZSTD_d_format: ::core::ffi::c_uint = 1000 as ::core::ffi::c_uint;
 #[no_mangle]
 pub unsafe extern "C" fn ZSTD_dParam_getBounds(mut dParam: ZSTD_dParameter) -> ::core::ffi::c_int {
     let mut bounds: ::core::ffi::c_int = 0 as ::core::ffi::c_int;
-    match dParam.0 {
-        100 => {
+    match dParam {
+        ZSTD_d_windowLogMax => {
             bounds = 1 as ::core::ffi::c_int;
             return bounds;
         }
-        ZSTD_d_format => {
+        ZSTD_d_experimentalParam1 => {
             bounds = 5 as ::core::ffi::c_int;
             return bounds;
         }

c2rust-transpile/tests/snapshots/snapshots__transpile@macrocase.c.2024.clang15.snap

@@ -21,12 +21,12 @@ pub const ZSTD_d_format: ::core::ffi::c_uint = 1000 as ::core::ffi::c_uint;
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn ZSTD_dParam_getBounds(mut dParam: ZSTD_dParameter) -> ::core::ffi::c_int {
     let mut bounds: ::core::ffi::c_int = 0 as ::core::ffi::c_int;
-    match dParam.0 {
-        100 => {
+    match dParam {
+        ZSTD_d_windowLogMax => {
             bounds = 1 as ::core::ffi::c_int;
             return bounds;
         }
-        ZSTD_d_format => {
+        ZSTD_d_experimentalParam1 => {
             bounds = 5 as ::core::ffi::c_int;
             return bounds;
         }