x86_64: implement union access

Author: jacobly0

lib/std/debug.zig

@@ -23,6 +23,7 @@ pub const Coverage = @import("debug/Coverage.zig");
 
 pub const FormattedPanic = @import("debug/FormattedPanic.zig");
 pub const SimplePanic = @import("debug/SimplePanic.zig");
+pub const NoPanic = @import("debug/NoPanic.zig");
 
 /// Unresolved source locations can be represented with a single `usize` that
 /// corresponds to a virtual memory address of the program counter. Combined

lib/std/debug/NoPanic.zig

@@ -0,0 +1,59 @@
+//! This namespace can be used with `pub const Panic = std.debug.NoPanic;` in the root file.
+//! It emits as little code as possible, for testing purposes.
+//!
+//! For a functional alternative, see `std.debug.FormattedPanic`.
+
+const std = @import("../std.zig");
+
+pub fn call(_: []const u8, _: ?*std.builtin.StackTrace, _: ?usize) noreturn {
+    @branchHint(.cold);
+    @trap();
+}
+
+pub inline fn sentinelMismatch(_: anytype, _: anytype) noreturn {
+    @branchHint(.cold);
+    @trap();
+}
+
+pub inline fn unwrapError(_: ?*std.builtin.StackTrace, _: anyerror) noreturn {
+    @branchHint(.cold);
+    @trap();
+}
+
+pub inline fn outOfBounds(_: usize, _: usize) noreturn {
+    @branchHint(.cold);
+    @trap();
+}
+
+pub inline fn startGreaterThanEnd(_: usize, _: usize) noreturn {
+    @branchHint(.cold);
+    @trap();
+}
+
+pub inline fn inactiveUnionField(_: anytype, _: anytype) noreturn {
+    @branchHint(.cold);
+    @trap();
+}
+
+pub const messages = struct {
+    pub const reached_unreachable = "";
+    pub const unwrap_null = "";
+    pub const cast_to_null = "";
+    pub const incorrect_alignment = "";
+    pub const invalid_error_code = "";
+    pub const cast_truncated_data = "";
+    pub const negative_to_unsigned = "";
+    pub const integer_overflow = "";
+    pub const shl_overflow = "";
+    pub const shr_overflow = "";
+    pub const divide_by_zero = "";
+    pub const exact_division_remainder = "";
+    pub const integer_part_out_of_bounds = "";
+    pub const corrupt_switch = "";
+    pub const shift_rhs_too_big = "";
+    pub const invalid_enum_value = "";
+    pub const for_len_mismatch = "";
+    pub const memcpy_len_mismatch = "";
+    pub const memcpy_alias = "";
+    pub const noreturn_returned = "";
+};