cImport causes "identifier cannot be empty" when accessing an unnamed field in a struct with a bitfield

Question

cImport causes "identifier cannot be empty" when accessing an unnamed field in a struct with a bitfield

pfgithub opened this issue 2 years ago · 2 comments

Zig Version

0.11.0-dev.3905+309aacfc8

Steps to Reproduce and Observed Behavior

// a.c
typedef struct {
    char fmt : 8;
    union {
        char maxLevel;
    };
} C3D_Tex;

char C3D_TexGetImagePtr(C3D_Tex tex) {
    return tex.maxLevel;
}

zig translate-c a.c > a.zig
zig ast-check a.zig

a.zig:58:16: error: identifier cannot be empty
    return tex.@"".maxLevel;

Expected Behavior

It should not block compilation, for example by accessing .unnamed_0 instead or generating a @compileError

Answer 1 · 2024-06-10T18:17:58.000Z

I just hit this again. This should maybe fix it:

diff --git a/src/translate_c.zig b/src/translate_c.zig
index 148b73955b..3806c5d174 100644
--- a/src/translate_c.zig
+++ b/src/translate_c.zig
@@ -3323,7 +3323,11 @@ fn transMemberExpr(c: *Context, scope: *Scope, stmt: *const clang.MemberExpr, re
             }
         }
         const decl = @as(*const clang.NamedDecl, @ptrCast(member_decl));
-        break :blk try c.str(decl.getName_bytes_begin());
+        const res = try c.str(decl.getName_bytes_begin());
+        if(res.len == 0) {
+            break :blk "anonymous";
+        }
+        break :blk res;
     };
 
     var node = try Tag.field_access.create(c.arena, .{ .lhs = container_node, .field_name = name });

but I still can't build zig to test it

error: sub-compilation of libcxx failed
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
error: sub-compilation of libcxxabi failed
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'
    :1:1: note: unable to create target: 'Unable to find target for this triple (no targets are registered)'

Answer 2 · 2024-07-15T13:11:58.000Z

The correct fix is to check if the struct was demoted to opaque and fail the function.

diff --git a/src/translate_c.zig b/src/translate_c.zig
index 8778310751..b027399c59 100644
--- a/src/translate_c.zig
+++ b/src/translate_c.zig
@@ -3305,6 +3305,8 @@ fn transStmtExpr(c: *Context, scope: *Scope, stmt: *const clang.StmtExpr, used:
 }
 
 fn transMemberExpr(c: *Context, scope: *Scope, stmt: *const clang.MemberExpr, result_used: ResultUsed) TransError!Node {
+    if (qualTypeWasDemotedToOpaque(c, stmt.getType()))
+        return fail(c, error.UnsupportedTranslation, stmt.getBeginLoc(), "cannot get member of struct demoted to opaque", .{});
     var container_node = try transExpr(c, scope, stmt.getBase(), .used);
     if (stmt.isArrow()) {
         container_node = try Tag.deref.create(c.arena, container_node);