llvm: Fix debug gen for 0-bit types

Add a regression test for that, since these weirdly never occur in any
of the other tests on x86-64-linux.

src/codegen/llvm.zig

@@ -2024,7 +2024,6 @@ pub const Object = struct {
             },
             .Int => {
                 const info = ty.intInfo(mod);
-                assert(info.bits != 0);
                 const int_name = try o.allocTypeName(ty);
                 defer gpa.free(int_name);
                 const builder_name = try o.builder.metadataString(int_name);
@@ -2206,7 +2205,6 @@ pub const Object = struct {
                 const debug_elem_type = switch (elem_ty.zigTypeTag(mod)) {
                     .Int => blk: {
                         const info = elem_ty.intInfo(mod);
-                        assert(info.bits != 0);
                         const vec_name = try o.allocTypeName(ty);
                         defer gpa.free(vec_name);
                         const builder_name = try o.builder.metadataString(vec_name);
@@ -2530,6 +2528,15 @@ pub const Object = struct {
                             if (owner == decl_id) continue;
                         }
 
+                        switch (nested_type.zigTypeTag(mod)) {
+                            // We still may want these for a Zig expression
+                            // evaluator in debuggers, but for now they are
+                            // completely useless.
+                            .ComptimeInt, .ComptimeFloat,
+                            .Type, .Undefined, .Null, .EnumLiteral => continue,
+                            else => {},
+                        }
+
                         fields.appendAssumeCapacity(try o.builder.debugTypedef(
                             try o.builder.metadataString(decl_name),
                             try o.getDebugFile(namespace.file_scope),

test/cases/llvm/debug_types.zig

@@ -0,0 +1,23 @@
+const Ty = struct {
+	pub const A = void;
+	pub const B = @Vector(2, u0);
+	pub const C = u0;
+	pub const D = enum (u0) {};
+	pub const E = type;
+	pub const F = 1;
+	pub const G = 1.0;
+	pub const H = undefined;
+	pub const I = null;
+	pub const J = .foo;
+};
+pub fn main() void {
+	inline for (@typeInfo(Ty).Struct.decls) |d|{
+		_ = @field(Ty, d.name);
+	}
+}
+
+// compile
+// output_mode=Exe
+// backend=llvm
+// target=x86_64-linux,x86_64-macos
+//