compiler: "illegal behavior", not "undefined behavior", in errors

Author: mlugg

src/Air.zig

@@ -37,7 +37,7 @@ pub const Inst = struct {
         /// liveness analysis without any special handling.
         /// Uses the `arg` field.
         arg,
-        /// Float or integer addition. For integers, wrapping is undefined behavior.
+        /// Float or integer addition. For integers, wrapping is illegal behavior.
         /// Both operands are guaranteed to be the same type, and the result type
         /// is the same as both operands.
         /// Uses the `bin_op` field.
@@ -66,7 +66,7 @@ pub const Inst = struct {
         /// is the same as both operands.
         /// Uses the `bin_op` field.
         add_sat,
-        /// Float or integer subtraction. For integers, wrapping is undefined behavior.
+        /// Float or integer subtraction. For integers, wrapping is illegal behavior.
         /// Both operands are guaranteed to be the same type, and the result type
         /// is the same as both operands.
         /// Uses the `bin_op` field.
@@ -95,7 +95,7 @@ pub const Inst = struct {
         /// is the same as both operands.
         /// Uses the `bin_op` field.
         sub_sat,
-        /// Float or integer multiplication. For integers, wrapping is undefined behavior.
+        /// Float or integer multiplication. For integers, wrapping is illegal behavior.
         /// Both operands are guaranteed to be the same type, and the result type
         /// is the same as both operands.
         /// Uses the `bin_op` field.
@@ -131,23 +131,23 @@ pub const Inst = struct {
         div_float,
         /// Same as `div_float` with optimized float mode.
         div_float_optimized,
-        /// Truncating integer or float division. For integers, wrapping is undefined behavior.
+        /// Truncating integer or float division. For integers, wrapping is illegal behavior.
         /// Both operands are guaranteed to be the same type, and the result type
         /// is the same as both operands.
         /// Uses the `bin_op` field.
         div_trunc,
         /// Same as `div_trunc` with optimized float mode.
         div_trunc_optimized,
-        /// Flooring integer or float division. For integers, wrapping is undefined behavior.
+        /// Flooring integer or float division. For integers, wrapping is illegal behavior.
         /// Both operands are guaranteed to be the same type, and the result type
         /// is the same as both operands.
         /// Uses the `bin_op` field.
         div_floor,
         /// Same as `div_floor` with optimized float mode.
         div_floor_optimized,
         /// Integer or float division.
-        /// If a remainder would be produced, undefined behavior occurs.
-        /// For integers, overflow is undefined behavior.
+        /// If a remainder would be produced, illegal behavior occurs.
+        /// For integers, overflow is illegal behavior.
         /// Both operands are guaranteed to be the same type, and the result type
         /// is the same as both operands.
         /// Uses the `bin_op` field.
@@ -170,14 +170,14 @@ pub const Inst = struct {
         mod_optimized,
         /// Add an offset to a pointer, returning a new pointer.
         /// The offset is in element type units, not bytes.
-        /// Wrapping is undefined behavior.
+        /// Wrapping is illegal behavior.
         /// The lhs is the pointer, rhs is the offset. Result type is the same as lhs.
         /// The pointer may be a slice.
         /// Uses the `ty_pl` field. Payload is `Bin`.
         ptr_add,
         /// Subtract an offset from a pointer, returning a new pointer.
         /// The offset is in element type units, not bytes.
-        /// Wrapping is undefined behavior.
+        /// Wrapping is illegal behavior.
         /// The lhs is the pointer, rhs is the offset. Result type is the same as lhs.
         /// The pointer may be a slice.
         /// Uses the `ty_pl` field. Payload is `Bin`.
@@ -577,10 +577,10 @@ pub const Inst = struct {
         /// sign but an equal or smaller number of bits.
         /// Uses the `ty_op` field.
         trunc,
-        /// ?T => T. If the value is null, undefined behavior.
+        /// ?T => T. If the value is null, illegal behavior.
         /// Uses the `ty_op` field.
         optional_payload,
-        /// *?T => *T. If the value is null, undefined behavior.
+        /// *?T => *T. If the value is null, illegal behavior.
         /// Uses the `ty_op` field.
         optional_payload_ptr,
         /// *?T => *T. Sets the value to non-null with an undefined payload value.
@@ -589,16 +589,16 @@ pub const Inst = struct {
         /// Given a payload value, wraps it in an optional type.
         /// Uses the `ty_op` field.
         wrap_optional,
-        /// E!T -> T. If the value is an error, undefined behavior.
+        /// E!T -> T. If the value is an error, illegal behavior.
         /// Uses the `ty_op` field.
         unwrap_errunion_payload,
-        /// E!T -> E. If the value is not an error, undefined behavior.
+        /// E!T -> E. If the value is not an error, illegal behavior.
         /// Uses the `ty_op` field.
         unwrap_errunion_err,
-        /// *(E!T) -> *T. If the value is an error, undefined behavior.
+        /// *(E!T) -> *T. If the value is an error, illegal behavior.
         /// Uses the `ty_op` field.
         unwrap_errunion_payload_ptr,
-        /// *(E!T) -> E. If the value is not an error, undefined behavior.
+        /// *(E!T) -> E. If the value is not an error, illegal behavior.
         /// Uses the `ty_op` field.
         unwrap_errunion_err_ptr,
         /// *(E!T) => *T. Sets the value to non-error with an undefined payload value.

src/Sema.zig

@@ -2327,11 +2327,11 @@ fn failWithNeededComptime(sema: *Sema, block: *Block, src: LazySrcLoc, reason: ?
 }
 
 pub fn failWithUseOfUndef(sema: *Sema, block: *Block, src: LazySrcLoc) CompileError {
-    return sema.fail(block, src, "use of undefined value here causes undefined behavior", .{});
+    return sema.fail(block, src, "use of undefined value here causes illegal behavior", .{});
 }
 
 pub fn failWithDivideByZero(sema: *Sema, block: *Block, src: LazySrcLoc) CompileError {
-    return sema.fail(block, src, "division by zero here causes undefined behavior", .{});
+    return sema.fail(block, src, "division by zero here causes illegal behavior", .{});
 }
 
 fn failWithModRemNegative(sema: *Sema, block: *Block, src: LazySrcLoc, lhs_ty: Type, rhs_ty: Type) CompileError {
@@ -15496,7 +15496,7 @@ fn zirDivExact(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Ai
     }
 
     // Depending on whether safety is enabled, we will have a slightly different strategy
-    // here. The `div_exact` AIR instruction causes undefined behavior if a remainder
+    // here. The `div_exact` AIR instruction causes illegal behavior if a remainder
     // is produced, so in the safety check case, it cannot be used. Instead we do a
     // div_trunc and check for remainder.
 
@@ -25266,7 +25266,7 @@ fn ptrSubtract(sema: *Sema, block: *Block, src: LazySrcLoc, ptr_val: Value, byte
     };
     if (ptr.byte_offset < byte_subtract) {
         return sema.failWithOwnedErrorMsg(block, msg: {
-            const msg = try sema.errMsg(src, "pointer computation here causes undefined behavior", .{});
+            const msg = try sema.errMsg(src, "pointer computation here causes illegal behavior", .{});
             errdefer msg.destroy(sema.gpa);
             try sema.errNote(src, msg, "resulting pointer exceeds bounds of containing value which may trigger overflow", .{});
             break :msg msg;

test/cases/compile_errors/add_assign_on_undefined_value.zig

@@ -5,4 +5,4 @@ comptime {
 
 // error
 //
-// :3:5: error: use of undefined value here causes undefined behavior
+// :3:5: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/and_on_undefined_value.zig

@@ -5,7 +5,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :4:9: error: use of undefined value here causes undefined behavior
+// :4:9: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/as_many_ptr_undefined.zig

@@ -4,7 +4,5 @@ export fn entry1() void {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :2:41: error: use of undefined value here causes undefined behavior
+// :2:41: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/branch_on_undefined_value.zig

@@ -5,7 +5,5 @@ export fn entry() usize {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :1:15: error: use of undefined value here causes undefined behavior
+// :1:15: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/catch_on_undefined_value.zig

@@ -4,7 +4,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:11: error: use of undefined value here causes undefined behavior
+// :3:11: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/comparing_against_undefined_produces_undefined_value.zig

@@ -8,5 +8,5 @@ export fn bar(x: u32) void {
 
 // error
 //
-// :2:11: error: use of undefined value here causes undefined behavior
-// :6:11: error: use of undefined value here causes undefined behavior
+// :2:11: error: use of undefined value here causes illegal behavior
+// :6:11: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/comparison_operators_with_undefined_value.zig

@@ -36,12 +36,10 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :5:11: error: use of undefined value here causes undefined behavior
-// :11:11: error: use of undefined value here causes undefined behavior
-// :17:11: error: use of undefined value here causes undefined behavior
-// :23:11: error: use of undefined value here causes undefined behavior
-// :29:11: error: use of undefined value here causes undefined behavior
-// :35:11: error: use of undefined value here causes undefined behavior
+// :5:11: error: use of undefined value here causes illegal behavior
+// :11:11: error: use of undefined value here causes illegal behavior
+// :17:11: error: use of undefined value here causes illegal behavior
+// :23:11: error: use of undefined value here causes illegal behavior
+// :29:11: error: use of undefined value here causes illegal behavior
+// :35:11: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/compile-time_division_by_zero.zig

@@ -6,7 +6,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :4:19: error: division by zero here causes undefined behavior
+// :4:19: error: division by zero here causes illegal behavior

test/cases/compile_errors/compile-time_remainder_division_by_zero.zig

@@ -6,7 +6,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :4:19: error: division by zero here causes undefined behavior
+// :4:19: error: division by zero here causes illegal behavior

test/cases/compile_errors/compile_time_division_by_zero.zig

@@ -8,8 +8,6 @@ export fn entry() usize {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:16: error: division by zero here causes undefined behavior
+// :3:16: error: division by zero here causes illegal behavior
 // :1:14: note: called from here

test/cases/compile_errors/compile_time_undef_ptr_cast.zig

@@ -6,7 +6,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:32: error: use of undefined value here causes undefined behavior
+// :3:32: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/div_assign_on_undefined_value.zig

@@ -5,4 +5,4 @@ comptime {
 
 // error
 //
-// :3:5: error: use of undefined value here causes undefined behavior
+// :3:5: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/division_by_zero.zig

@@ -17,9 +17,7 @@ export fn entry4() usize {
 } // no error on purpose
 
 // error
-// backend=stage2
-// target=native
 //
-// :1:23: error: division by zero here causes undefined behavior
-// :2:27: error: division by zero here causes undefined behavior
-// :3:29: error: division by zero here causes undefined behavior
+// :1:23: error: division by zero here causes illegal behavior
+// :2:27: error: division by zero here causes illegal behavior
+// :3:29: error: division by zero here causes illegal behavior

test/cases/compile_errors/indexing_a_undefined_slice_at_comptime.zig

@@ -4,7 +4,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:10: error: use of undefined value here causes undefined behavior
+// :3:10: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/lazy_pointer_with_undefined_element_type.zig

@@ -7,7 +7,5 @@ export fn foo() void {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :4:28: error: use of undefined value here causes undefined behavior
+// :4:28: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/mod_assign_on_undefined_value.zig

@@ -4,7 +4,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:5: error: use of undefined value here causes undefined behavior
+// :3:5: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/mod_on_undefined_value.zig

@@ -5,7 +5,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:9: error: use of undefined value here causes undefined behavior
+// :3:9: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/mult_assign_on_undefined_value.zig

@@ -5,4 +5,4 @@ comptime {
 
 // error
 //
-// :3:5: error: use of undefined value here causes undefined behavior
+// :3:5: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/negate_on_undefined_value.zig

@@ -4,7 +4,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:10: error: use of undefined value here causes undefined behavior
+// :3:10: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/or_on_undefined_value.zig

@@ -5,7 +5,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :4:9: error: use of undefined value here causes undefined behavior
+// :4:9: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/orelse_on_undefined_value.zig

@@ -4,7 +4,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:11: error: use of undefined value here causes undefined behavior
+// :3:11: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/pointer_exceeds_containing_value.zig

@@ -13,7 +13,7 @@ export fn entry2() void {
 
 // error
 //
-// :4:13: error: pointer computation here causes undefined behavior
+// :4:13: error: pointer computation here causes illegal behavior
 // :4:13: note: resulting pointer exceeds bounds of containing value which may trigger overflow
-// :10:55: error: pointer computation here causes undefined behavior
+// :10:55: error: pointer computation here causes illegal behavior
 // :10:55: note: resulting pointer exceeds bounds of containing value which may trigger overflow

test/cases/compile_errors/refer_to_the_type_of_a_generic_function.zig

@@ -5,7 +5,5 @@ export fn entry() void {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :4:6: error: use of undefined value here causes undefined behavior
+// :4:6: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/reify_type_for_exhaustive_enum_with_undefined_tag_type.zig

@@ -11,7 +11,5 @@ export fn entry() void {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :1:20: error: use of undefined value here causes undefined behavior
+// :1:20: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/reify_type_union_payload_is_undefined.zig

@@ -6,7 +6,5 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :1:20: error: use of undefined value here causes undefined behavior
+// :1:20: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/reify_type_with_undefined.zig

@@ -25,9 +25,7 @@ comptime {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :2:16: error: use of undefined value here causes undefined behavior
-// :5:16: error: use of undefined value here causes undefined behavior
-// :17:16: error: use of undefined value here causes undefined behavior
+// :2:16: error: use of undefined value here causes illegal behavior
+// :5:16: error: use of undefined value here causes illegal behavior
+// :17:16: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/slice_end_index_undefined.zig

@@ -4,7 +4,5 @@ export fn a() void {
 }
 
 // error
-// backend=stage2
-// target=native
 //
-// :3:18: error: use of undefined value here causes undefined behavior
+// :3:18: error: use of undefined value here causes illegal behavior

test/cases/compile_errors/sub_assign_on_undefined_value.zig

@@ -5,4 +5,4 @@ comptime {
 
 // error
 //
-// :3:5: error: use of undefined value here causes undefined behavior
+// :3:5: error: use of undefined value here causes illegal behavior