c-to-zig: handle UO_Deref

src/ast_render.cpp

@@ -625,7 +625,7 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
                     fprintf(ar->f, "@");
                 }
                 AstNode *fn_ref_node = node->data.fn_call_expr.fn_ref_expr;
-                bool grouped = (fn_ref_node->type != NodeTypeBinOpExpr);
+                bool grouped = (fn_ref_node->type != NodeTypePrefixOpExpr);
                 render_node_extra(ar, fn_ref_node, grouped);
                 fprintf(ar->f, "(");
                 for (size_t i = 0; i < node->data.fn_call_expr.params.length; i += 1) {

src/parsec.cpp

@@ -350,6 +350,21 @@ static AstNode* trans_c_cast(Context *c, const SourceLocation &source_location,
     return trans_create_node_fn_call_1(c, trans_qual_type(c, qt, source_location), expr);
 }
 
+static bool qual_type_is_fn_ptr(Context *c, const QualType &qt) {
+    const Type *ty = qt.getTypePtr();
+    if (ty->getTypeClass() != Type::Pointer) {
+        return false;
+    }
+    const PointerType *pointer_ty = static_cast<const PointerType*>(ty);
+    QualType child_qt = pointer_ty->getPointeeType();
+    const Type *child_ty = child_qt.getTypePtr();
+    if (child_ty->getTypeClass() != Type::Paren) {
+        return false;
+    }
+    const ParenType *paren_ty = static_cast<const ParenType *>(child_ty);
+    return paren_ty->getInnerType().getTypePtr()->getTypeClass() == Type::FunctionProto;
+}
+
 static uint32_t qual_type_int_bit_width(Context *c, const QualType &qt, const SourceLocation &source_loc) {
     const Type *ty = qt.getTypePtr();
     switch (ty->getTypeClass()) {
@@ -1575,8 +1590,14 @@ static AstNode *trans_unary_operator(Context *c, bool result_used, AstNode *bloc
             emit_warning(c, stmt->getLocStart(), "TODO handle C translation UO_AddrOf");
             return nullptr;
         case UO_Deref:
-            emit_warning(c, stmt->getLocStart(), "TODO handle C translation UO_Deref");
-            return nullptr;
+            {
+                bool is_fn_ptr = qual_type_is_fn_ptr(c, stmt->getSubExpr()->getType());
+                AstNode *value_node = trans_expr(c, result_used, block, stmt->getSubExpr(), TransRValue);
+                if (is_fn_ptr)
+                    return value_node;
+                AstNode *unwrapped = trans_create_node_prefix_op(c, PrefixOpUnwrapMaybe, value_node);
+                return trans_create_node_prefix_op(c, PrefixOpDereference, unwrapped);
+            }
         case UO_Plus:
             emit_warning(c, stmt->getLocStart(), "TODO handle C translation UO_Plus");
             return nullptr;
@@ -1919,10 +1940,20 @@ static AstNode *trans_if_statement(Context *c, AstNode *block, IfStmt *stmt) {
 
 static AstNode *trans_call_expr(Context *c, bool result_used, AstNode *block, CallExpr *stmt) {
     AstNode *node = trans_create_node(c, NodeTypeFnCallExpr);
-    node->data.fn_call_expr.fn_ref_expr = trans_expr(c, true, block, stmt->getCallee(), TransRValue);
-    if (node->data.fn_call_expr.fn_ref_expr == nullptr)
+
+    AstNode *callee_raw_node = trans_expr(c, true, block, stmt->getCallee(), TransRValue);
+    if (callee_raw_node == nullptr)
         return nullptr;
 
+    AstNode *callee_node;
+    if (qual_type_is_fn_ptr(c, stmt->getCallee()->getType())) {
+        callee_node = trans_create_node_prefix_op(c, PrefixOpUnwrapMaybe, callee_raw_node);
+    } else {
+        callee_node = callee_raw_node;
+    }
+
+    node->data.fn_call_expr.fn_ref_expr = callee_node;
+
     unsigned num_args = stmt->getNumArgs();
     Expr **args = stmt->getArgs();
     for (unsigned i = 0; i < num_args; i += 1) {

test/parsec.zig

@@ -203,13 +203,13 @@ pub fn addCases(cases: &tests.ParseCContext) {
         \\pub extern var fn_ptr: ?extern fn();
     ,
         \\pub inline fn foo() {
-        \\    ??fn_ptr()
+        \\    (??fn_ptr)()
         \\}
     ,
         \\pub extern var fn_ptr2: ?extern fn(c_int, f32) -> u8;
     ,
         \\pub inline fn bar(arg0: c_int, arg1: f32) -> u8 {
-        \\    ??fn_ptr2(arg0, arg1)
+        \\    (??fn_ptr2)(arg0, arg1)
         \\}
     );
 
@@ -831,6 +831,32 @@ pub fn addCases(cases: &tests.ParseCContext) {
         \\    };
         \\}
     );
+
+    cases.addC("deref function pointer",
+        \\void foo(void) {}
+        \\void bar(void) {
+        \\    void(*f)(void) = foo;
+        \\    f();
+        \\    (*(f))();
+        \\}
+    ,
+        \\export fn foo() {}
+        \\export fn bar() {
+        \\    var f: ?extern fn() = foo;
+        \\    (??f)();
+        \\    (??f)();
+        \\}
+    );
+
+    cases.addC("normal deref",
+        \\void foo(int *x) {
+        \\    *x = 1;
+        \\}
+    ,
+        \\export fn foo(x: ?&c_int) {
+        \\    (*(??x)) = 1;
+        \\}
+    );
 }