conditional fields of constexpr literal structs

src/bindgen/ir/constant.rs

@@ -78,6 +78,12 @@ pub(crate) fn to_known_assoc_constant(associated_to: &Path, name: &str) -> Optio
     Some(format!("{}_{}", prefix, name))
 }
 
+#[derive(Debug, Clone)]
+pub struct LiteralStructField {
+    pub value: Literal,
+    pub cfg: Option<Cfg>,
+}
+
 #[derive(Debug, Clone)]
 pub enum Literal {
     Expr(String),
@@ -101,7 +107,7 @@ pub enum Literal {
     Struct {
         path: Path,
         export_name: String,
-        fields: HashMap<String, Literal>,
+        fields: HashMap<String, LiteralStructField>,
     },
     Cast {
         ty: Type,
@@ -135,7 +141,7 @@ impl Literal {
                     self_ty.name().clone_into(export_name);
                 }
                 for ref mut expr in fields.values_mut() {
-                    expr.replace_self_with(self_ty);
+                    expr.value.replace_self_with(self_ty);
                 }
             }
             Literal::Cast {
@@ -203,7 +209,7 @@ impl Literal {
             Literal::FieldAccess { ref base, .. } => base.visit(visitor),
             Literal::Struct { ref fields, .. } => {
                 for (_name, field) in fields.iter() {
-                    if !field.visit(visitor) {
+                    if !field.value.visit(visitor) {
                         return false;
                     }
                 }
@@ -250,7 +256,7 @@ impl Literal {
             } => {
                 config.export.rename(export_name);
                 for lit in fields.values_mut() {
-                    lit.rename_for_config(config);
+                    lit.value.rename_for_config(config);
                 }
             }
             Literal::FieldAccess { ref mut base, .. } => {
@@ -388,12 +394,13 @@ impl Literal {
                     } => name,
                     _ => return Err(format!("Unsupported call expression. {:?}", *expr)),
                 };
-                let mut fields = HashMap::<String, Literal>::default();
+                let mut fields = HashMap::<String, LiteralStructField>::default();
                 for (index, arg) in args.iter().enumerate() {
                     let ident =
                         member_to_ident(&syn::Member::Unnamed(syn::Index::from(index))).to_string();
                     let value = Literal::load(arg)?;
-                    fields.insert(ident, value);
+                    let field = LiteralStructField { value, cfg: None };
+                    fields.insert(ident, field);
                 }
                 Ok(Literal::Struct {
                     path: Path::new(struct_name.clone()),
@@ -408,11 +415,13 @@ impl Literal {
                 ..
             }) => {
                 let struct_name = path.segments[0].ident.unraw().to_string();
-                let mut field_map = HashMap::<String, Literal>::default();
+                let mut field_map = HashMap::<String, LiteralStructField>::default();
                 for field in fields {
                     let ident = member_to_ident(&field.member).to_string();
+                    let cfg = Cfg::load(&field.attrs);
                     let value = Literal::load(&field.expr)?;
-                    field_map.insert(ident, value);
+                    let field = LiteralStructField { value, cfg };
+                    field_map.insert(ident, field);
                 }
                 Ok(Literal::Struct {
                     path: Path::new(struct_name.clone()),
@@ -682,7 +691,7 @@ impl Constant {
             if !out.bindings().struct_is_transparent(path) {
                 break;
             }
-            value = fields.iter().next().unwrap().1
+            value = &fields.iter().next().unwrap().1.value
         }
 
         language_backend.write_documentation(out, self.documentation());

src/bindgen/language_backend/clike.rs

@@ -912,19 +912,19 @@ impl LanguageBackend for CLikeLanguageBackend<'_> {
                 let ordered_fields = out.bindings().struct_field_names(path);
                 for (i, ordered_key) in ordered_fields.iter().enumerate() {
                     if let Some(lit) = fields.get(ordered_key) {
+                        let condition = lit.cfg.to_condition(self.config);
                         if is_constexpr {
                             out.new_line();
 
+                            condition.write_before(self.config, out);
                             // TODO: Some C++ versions (c++20?) now support designated
                             // initializers, consider generating them.
                             write!(out, "/* .{} = */ ", ordered_key);
-                            self.write_literal(out, lit);
+                            self.write_literal(out, &lit.value);
                             if i + 1 != ordered_fields.len() {
                                 write!(out, ",");
-                                if !is_constexpr {
-                                    write!(out, " ");
-                                }
                             }
+                            condition.write_after(self.config, out);
                         } else {
                             if i > 0 {
                                 write!(out, ", ");
@@ -937,7 +937,7 @@ impl LanguageBackend for CLikeLanguageBackend<'_> {
                             } else {
                                 write!(out, ".{} = ", ordered_key);
                             }
-                            self.write_literal(out, lit);
+                            self.write_literal(out, &lit.value);
                         }
                     }
                 }

src/bindgen/language_backend/cython.rs

@@ -399,7 +399,7 @@ impl LanguageBackend for CythonLanguageBackend<'_> {
                         } else {
                             is_first_field = false;
                         }
-                        self.write_literal(out, lit);
+                        self.write_literal(out, &lit.value);
                     }
                 }
                 write!(out, " }}");

tests/expectations/cfg.c

@@ -77,6 +77,8 @@ typedef struct {
 #endif
   ;
 } ConditionalField;
+#define ConditionalField_ZERO (ConditionalField){ .field = 0 }
+#define ConditionalField_ONE (ConditionalField){ .field = 1 }
 
 typedef struct {
   int32_t x;

tests/expectations/cfg.compat.c

@@ -95,6 +95,8 @@ typedef struct {
 #endif
   ;
 } ConditionalField;
+#define ConditionalField_ZERO (ConditionalField){ .field = 0 }
+#define ConditionalField_ONE (ConditionalField){ .field = 1 }
 
 typedef struct {
   int32_t x;

tests/expectations/cfg.cpp

@@ -201,6 +201,16 @@ struct ConditionalField {
 #endif
   ;
 };
+constexpr static const ConditionalField ConditionalField_ZERO = ConditionalField{
+#if defined(X11)
+  /* .field = */ 0
+#endif
+};
+constexpr static const ConditionalField ConditionalField_ONE = ConditionalField{
+#if defined(X11)
+  /* .field = */ 1
+#endif
+};
 
 struct Normal {
   int32_t x;

tests/expectations/cfg.pyx

@@ -57,6 +57,8 @@ cdef extern from *:
 
   ctypedef struct ConditionalField:
     int32_t field;
+  const ConditionalField ConditionalField_ZERO # = <ConditionalField>{ 0 }
+  const ConditionalField ConditionalField_ONE # = <ConditionalField>{ 1 }
 
   ctypedef struct Normal:
     int32_t x;

tests/expectations/cfg_both.c

@@ -77,6 +77,8 @@ typedef struct ConditionalField {
 #endif
   ;
 } ConditionalField;
+#define ConditionalField_ZERO (ConditionalField){ .field = 0 }
+#define ConditionalField_ONE (ConditionalField){ .field = 1 }
 
 typedef struct Normal {
   int32_t x;

tests/expectations/cfg_both.compat.c

@@ -95,6 +95,8 @@ typedef struct ConditionalField {
 #endif
   ;
 } ConditionalField;
+#define ConditionalField_ZERO (ConditionalField){ .field = 0 }
+#define ConditionalField_ONE (ConditionalField){ .field = 1 }
 
 typedef struct Normal {
   int32_t x;

tests/expectations/cfg_tag.c

@@ -77,6 +77,8 @@ struct ConditionalField {
 #endif
   ;
 };
+#define ConditionalField_ZERO (ConditionalField){ .field = 0 }
+#define ConditionalField_ONE (ConditionalField){ .field = 1 }
 
 struct Normal {
   int32_t x;

tests/expectations/cfg_tag.compat.c

@@ -95,6 +95,8 @@ struct ConditionalField {
 #endif
   ;
 };
+#define ConditionalField_ZERO (ConditionalField){ .field = 0 }
+#define ConditionalField_ONE (ConditionalField){ .field = 1 }
 
 struct Normal {
   int32_t x;

tests/expectations/cfg_tag.pyx

@@ -57,6 +57,8 @@ cdef extern from *:
 
   cdef struct ConditionalField:
     int32_t field;
+  const ConditionalField ConditionalField_ZERO # = <ConditionalField>{ 0 }
+  const ConditionalField ConditionalField_ONE # = <ConditionalField>{ 1 }
 
   cdef struct Normal:
     int32_t x;

tests/rust/cfg.rs

@@ -49,6 +49,17 @@ struct ConditionalField {
     field: i32,
 }
 
+impl ConditionalField {
+    pub const ZERO: Self = Self {
+        #[cfg(x11)]
+        field: 0,
+    };
+    pub const ONE: Self = Self {
+        #[cfg(x11)]
+        field: 1,
+    };
+}
+
 #[cfg(all(unix, x11))]
 #[no_mangle]
 pub extern "C" fn root(a: FooHandle, c: C)