diff --git a/lib/std/fs.zig b/lib/std/fs.zig
index 3ef8e5319c..8ae21259ae 100644
--- a/lib/std/fs.zig
+++ b/lib/std/fs.zig
@@ -809,8 +809,6 @@ pub const IterableDir = struct {
                 // and we avoid the code complexity here.
                 const w = os.wasi;
                 start_over: while (true) {
-                    // TODO https://github.com/ziglang/zig/issues/12498
-                    _ = @sizeOf(w.dirent_t) + 1;
                     // According to the WASI spec, the last entry might be truncated,
                     // so we need to check if the left buffer contains the whole dirent.
                     if (self.end_index - self.index < @sizeOf(w.dirent_t)) {
diff --git a/src/AstGen.zig b/src/AstGen.zig
index 009d05e5ed..4e571ffda9 100644
--- a/src/AstGen.zig
+++ b/src/AstGen.zig
@@ -2632,7 +2632,7 @@ fn addEnsureResult(gz: *GenZir, maybe_unused_result: Zir.Inst.Ref, statement: As
             .compile_error,
             .ret_node,
             .ret_load,
-            .ret_tok,
+            .ret_implicit,
             .ret_err_value,
             .@"unreachable",
             .repeat,
@@ -3696,6 +3696,29 @@ fn fnDecl(
                 if (param.anytype_ellipsis3) |tok| {
                     return astgen.failTok(tok, "missing parameter name", .{});
                 } else {
+                    ambiguous: {
+                        if (tree.nodes.items(.tag)[param.type_expr] != .identifier) break :ambiguous;
+                        const main_token = tree.nodes.items(.main_token)[param.type_expr];
+                        const identifier_str = tree.tokenSlice(main_token);
+                        if (isPrimitive(identifier_str)) break :ambiguous;
+                        return astgen.failNodeNotes(
+                            param.type_expr,
+                            "missing parameter name or type",
+                            .{},
+                            &[_]u32{
+                                try astgen.errNoteNode(
+                                    param.type_expr,
+                                    "if this is a name, annotate its type '{s}: T'",
+                                    .{identifier_str},
+                                ),
+                                try astgen.errNoteNode(
+                                    param.type_expr,
+                                    "if this is a type, give it a name '<name>: {s}'",
+                                    .{identifier_str},
+                                ),
+                            },
+                        );
+                    }
                     return astgen.failNode(param.type_expr, "missing parameter name", .{});
                 }
             } else 0;
@@ -3891,9 +3914,8 @@ fn fnDecl(
             // As our last action before the return, "pop" the error trace if needed
             _ = try gz.addRestoreErrRetIndex(.ret, .always);
 
-            // Since we are adding the return instruction here, we must handle the coercion.
-            // We do this by using the `ret_tok` instruction.
-            _ = try fn_gz.addUnTok(.ret_tok, .void_value, tree.lastToken(body_node));
+            // Add implicit return at end of function.
+            _ = try fn_gz.addUnTok(.ret_implicit, .void_value, tree.lastToken(body_node));
         }
 
         break :func try decl_gz.addFunc(.{
@@ -4311,9 +4333,8 @@ fn testDecl(
         // As our last action before the return, "pop" the error trace if needed
         _ = try gz.addRestoreErrRetIndex(.ret, .always);
 
-        // Since we are adding the return instruction here, we must handle the coercion.
-        // We do this by using the `ret_tok` instruction.
-        _ = try fn_block.addUnTok(.ret_tok, .void_value, tree.lastToken(body_node));
+        // Add implicit return at end of function.
+        _ = try fn_block.addUnTok(.ret_implicit, .void_value, tree.lastToken(body_node));
     }
 
     const func_inst = try decl_block.addFunc(.{
@@ -5605,6 +5626,14 @@ fn simpleBinOp(
     const tree = astgen.tree;
     const node_datas = tree.nodes.items(.data);
 
+    if (op_inst_tag == .cmp_neq or op_inst_tag == .cmp_eq) {
+        const node_tags = tree.nodes.items(.tag);
+        const str = if (op_inst_tag == .cmp_eq) "==" else "!=";
+        if (node_tags[node_datas[node].lhs] == .string_literal or
+            node_tags[node_datas[node].rhs] == .string_literal)
+            return astgen.failNode(node, "cannot compare strings with {s}", .{str});
+    }
+
     const lhs = try reachableExpr(gz, scope, .{ .rl = .none }, node_datas[node].lhs, node);
     var line: u32 = undefined;
     var column: u32 = undefined;
@@ -6602,6 +6631,11 @@ fn switchExpr(
             continue;
         }
 
+        for (case.ast.values) |val| {
+            if (node_tags[val] == .string_literal)
+                return astgen.failNode(val, "cannot switch on strings", .{});
+        }
+
         if (case.ast.values.len == 1 and node_tags[case.ast.values[0]] != .switch_range) {
             scalar_cases_len += 1;
         } else {
diff --git a/src/Module.zig b/src/Module.zig
index a18297c8ff..68d0ac8af5 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -940,6 +940,7 @@ pub const Struct = struct {
     requires_comptime: PropertyBoolean = .unknown,
     have_field_inits: bool = false,
     is_tuple: bool,
+    assumed_runtime_bits: bool = false,
 
     pub const Fields = std.StringArrayHashMapUnmanaged(Field);
 
@@ -1205,6 +1206,7 @@ pub const Union = struct {
         fully_resolved,
     },
     requires_comptime: PropertyBoolean = .unknown,
+    assumed_runtime_bits: bool = false,
 
     pub const Field = struct {
         /// undefined until `status` is `have_field_types` or `have_layout`.
diff --git a/src/Sema.zig b/src/Sema.zig
index c384605e1b..09fd184320 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -291,8 +291,8 @@ pub const Block = struct {
                     try sema.errNote(ci.block, ci.src, parent, prefix ++ "it is inside a @cImport", .{});
                 },
                 .comptime_ret_ty => |rt| {
-                    const src_loc = if (try sema.funcDeclSrc(rt.func)) |capture| blk: {
-                        var src_loc = capture;
+                    const src_loc = if (try sema.funcDeclSrc(rt.func)) |fn_decl| blk: {
+                        var src_loc = fn_decl.srcLoc();
                         src_loc.lazy = .{ .node_offset_fn_type_ret_ty = 0 };
                         break :blk src_loc;
                     } else blk: {
@@ -1098,7 +1098,7 @@ fn analyzeBodyInner(
             // These functions match the return type of analyzeBody so that we can
             // tail call them here.
             .compile_error  => break sema.zirCompileError(block, inst),
-            .ret_tok        => break sema.zirRetTok(block, inst),
+            .ret_implicit   => break sema.zirRetImplicit(block, inst),
             .ret_node       => break sema.zirRetNode(block, inst),
             .ret_load       => break sema.zirRetLoad(block, inst),
             .ret_err_value  => break sema.zirRetErrValue(block, inst),
@@ -5843,7 +5843,7 @@ fn lookupInNamespace(
     return null;
 }
 
-fn funcDeclSrc(sema: *Sema, func_inst: Air.Inst.Ref) !?Module.SrcLoc {
+fn funcDeclSrc(sema: *Sema, func_inst: Air.Inst.Ref) !?*Decl {
     const func_val = (try sema.resolveMaybeUndefVal(func_inst)) orelse return null;
     if (func_val.isUndef()) return null;
     const owner_decl_index = switch (func_val.tag()) {
@@ -5852,8 +5852,7 @@ fn funcDeclSrc(sema: *Sema, func_inst: Air.Inst.Ref) !?Module.SrcLoc {
         .decl_ref => sema.mod.declPtr(func_val.castTag(.decl_ref).?.data).val.castTag(.function).?.data.owner_decl,
         else => return null,
     };
-    const owner_decl = sema.mod.declPtr(owner_decl_index);
-    return owner_decl.srcLoc();
+    return sema.mod.declPtr(owner_decl_index);
 }
 
 pub fn analyzeSaveErrRetIndex(sema: *Sema, block: *Block) SemaError!Air.Inst.Ref {
@@ -6031,7 +6030,7 @@ fn zirCall(
             break :check_args;
         }
 
-        const decl_src = try sema.funcDeclSrc(func);
+        const maybe_decl = try sema.funcDeclSrc(func);
         const member_str = if (bound_arg_src != null) "member function " else "";
         const variadic_str = if (func_ty_info.is_var_args) "at least " else "";
         const msg = msg: {
@@ -6048,7 +6047,7 @@ fn zirCall(
             );
             errdefer msg.destroy(sema.gpa);
 
-            if (decl_src) |some| try sema.mod.errNoteNonLazy(some, msg, "function declared here", .{});
+            if (maybe_decl) |fn_decl| try sema.mod.errNoteNonLazy(fn_decl.srcLoc(), msg, "function declared here", .{});
             break :msg msg;
         };
         return sema.failWithOwnedErrorMsg(msg);
@@ -6242,7 +6241,7 @@ fn analyzeCall(
     const func_ty_info = func_ty.fnInfo();
     const cc = func_ty_info.cc;
     if (cc == .Naked) {
-        const decl_src = try sema.funcDeclSrc(func);
+        const maybe_decl = try sema.funcDeclSrc(func);
         const msg = msg: {
             const msg = try sema.errMsg(
                 block,
@@ -6252,7 +6251,7 @@ fn analyzeCall(
             );
             errdefer msg.destroy(sema.gpa);
 
-            if (decl_src) |some| try sema.mod.errNoteNonLazy(some, msg, "function declared here", .{});
+            if (maybe_decl) |fn_decl| try sema.mod.errNoteNonLazy(fn_decl.srcLoc(), msg, "function declared here", .{});
             break :msg msg;
         };
         return sema.failWithOwnedErrorMsg(msg);
@@ -6488,6 +6487,7 @@ fn analyzeCall(
                 &should_memoize,
                 memoized_call_key,
                 func_ty_info.param_types,
+                func,
             ) catch |err| switch (err) {
                 error.NeededSourceLocation => {
                     _ = sema.inst_map.remove(inst);
@@ -6504,6 +6504,7 @@ fn analyzeCall(
                         &should_memoize,
                         memoized_call_key,
                         func_ty_info.param_types,
+                        func,
                     );
                     return error.AnalysisFail;
                 },
@@ -6646,12 +6647,17 @@ fn analyzeCall(
         const args = try sema.arena.alloc(Air.Inst.Ref, uncasted_args.len);
         for (uncasted_args) |uncasted_arg, i| {
             if (i < fn_params_len) {
+                const opts: CoerceOpts = .{ .param_src = .{
+                    .func_inst = func,
+                    .param_i = @intCast(u32, i),
+                } };
                 const param_ty = func_ty.fnParamType(i);
                 args[i] = sema.analyzeCallArg(
                     block,
                     .unneeded,
                     param_ty,
                     uncasted_arg,
+                    opts,
                 ) catch |err| switch (err) {
                     error.NeededSourceLocation => {
                         const decl = sema.mod.declPtr(block.src_decl);
@@ -6660,6 +6666,7 @@ fn analyzeCall(
                             Module.argSrc(call_src.node_offset.x, sema.gpa, decl, i, bound_arg_src),
                             param_ty,
                             uncasted_arg,
+                            opts,
                         );
                         return error.AnalysisFail;
                     },
@@ -6741,6 +6748,7 @@ fn analyzeInlineCallArg(
     should_memoize: *bool,
     memoized_call_key: Module.MemoizedCall.Key,
     raw_param_types: []const Type,
+    func_inst: Air.Inst.Ref,
 ) !void {
     const zir_tags = sema.code.instructions.items(.tag);
     switch (zir_tags[inst]) {
@@ -6765,7 +6773,13 @@ fn analyzeInlineCallArg(
                     return err;
                 };
             }
-            const casted_arg = try sema.coerce(arg_block, param_ty, uncasted_arg, arg_src);
+            const casted_arg = sema.coerceExtra(arg_block, param_ty, uncasted_arg, arg_src, .{ .param_src = .{
+                .func_inst = func_inst,
+                .param_i = @intCast(u32, arg_i.*),
+            } }) catch |err| switch (err) {
+                error.NotCoercible => unreachable,
+                else => |e| return e,
+            };
 
             if (is_comptime_call) {
                 sema.inst_map.putAssumeCapacityNoClobber(inst, casted_arg);
@@ -6855,9 +6869,13 @@ fn analyzeCallArg(
     arg_src: LazySrcLoc,
     param_ty: Type,
     uncasted_arg: Air.Inst.Ref,
+    opts: CoerceOpts,
 ) !Air.Inst.Ref {
     try sema.resolveTypeFully(param_ty);
-    return sema.coerce(block, param_ty, uncasted_arg, arg_src);
+    return sema.coerceExtra(block, param_ty, uncasted_arg, arg_src, opts) catch |err| switch (err) {
+        error.NotCoercible => unreachable,
+        else => |e| return e,
+    };
 }
 
 fn analyzeGenericCallArg(
@@ -16546,7 +16564,7 @@ fn zirRetErrValue(
     return sema.analyzeRet(block, result_inst, src);
 }
 
-fn zirRetTok(
+fn zirRetImplicit(
     sema: *Sema,
     block: *Block,
     inst: Zir.Inst.Index,
@@ -16556,9 +16574,33 @@ fn zirRetTok(
 
     const inst_data = sema.code.instructions.items(.data)[inst].un_tok;
     const operand = try sema.resolveInst(inst_data.operand);
-    const src = inst_data.src();
 
-    return sema.analyzeRet(block, operand, src);
+    const r_brace_src = inst_data.src();
+    const ret_ty_src: LazySrcLoc = .{ .node_offset_fn_type_ret_ty = 0 };
+    const base_tag = sema.fn_ret_ty.baseZigTypeTag();
+    if (base_tag == .NoReturn) {
+        const msg = msg: {
+            const msg = try sema.errMsg(block, ret_ty_src, "function declared '{}' implicitly returns", .{
+                sema.fn_ret_ty.fmt(sema.mod),
+            });
+            errdefer msg.destroy(sema.gpa);
+            try sema.errNote(block, r_brace_src, msg, "control flow reaches end of body here", .{});
+            break :msg msg;
+        };
+        return sema.failWithOwnedErrorMsg(msg);
+    } else if (base_tag != .Void) {
+        const msg = msg: {
+            const msg = try sema.errMsg(block, ret_ty_src, "function with non-void return type '{}' implicitly returns", .{
+                sema.fn_ret_ty.fmt(sema.mod),
+            });
+            errdefer msg.destroy(sema.gpa);
+            try sema.errNote(block, r_brace_src, msg, "control flow reaches end of body here", .{});
+            break :msg msg;
+        };
+        return sema.failWithOwnedErrorMsg(msg);
+    }
+
+    return sema.analyzeRet(block, operand, .unneeded);
 }
 
 fn zirRetNode(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Zir.Inst.Index {
@@ -16825,7 +16867,7 @@ fn zirPtrType(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
     const bitoffset_src: LazySrcLoc = .{ .node_offset_ptr_bitoffset = extra.data.src_node };
     const hostsize_src: LazySrcLoc = .{ .node_offset_ptr_hostsize = extra.data.src_node };
 
-    const unresolved_elem_ty = blk: {
+    const elem_ty = blk: {
         const air_inst = try sema.resolveInst(extra.data.elem_type);
         const ty = sema.analyzeAsType(block, elem_ty_src, air_inst) catch |err| {
             if (err == error.AnalysisFail and sema.err != null and sema.typeOf(air_inst).isSinglePointer()) {
@@ -16854,7 +16896,7 @@ fn zirPtrType(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
         // Check if this happens to be the lazy alignment of our element type, in
         // which case we can make this 0 without resolving it.
         if (val.castTag(.lazy_align)) |payload| {
-            if (payload.data.eql(unresolved_elem_ty, sema.mod)) {
+            if (payload.data.eql(elem_ty, sema.mod)) {
                 break :blk 0;
             }
         }
@@ -16887,14 +16929,6 @@ fn zirPtrType(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
         return sema.fail(block, bitoffset_src, "bit offset starts after end of host integer", .{});
     }
 
-    const elem_ty = if (abi_align == 0)
-        unresolved_elem_ty
-    else t: {
-        const elem_ty = try sema.resolveTypeFields(unresolved_elem_ty);
-        try sema.resolveTypeLayout(elem_ty);
-        break :t elem_ty;
-    };
-
     if (elem_ty.zigTypeTag() == .NoReturn) {
         return sema.fail(block, elem_ty_src, "pointer to noreturn not allowed", .{});
     } else if (elem_ty.zigTypeTag() == .Fn) {
@@ -20270,7 +20304,7 @@ fn analyzeShuffle(
         var buf: Value.ElemValueBuffer = undefined;
         const elem = mask.elemValueBuffer(sema.mod, i, &buf);
         if (elem.isUndef()) continue;
-        const int = elem.toSignedInt();
+        const int = elem.toSignedInt(sema.mod.getTarget());
         var unsigned: u32 = undefined;
         var chosen: u32 = undefined;
         if (int >= 0) {
@@ -20312,7 +20346,7 @@ fn analyzeShuffle(
                     values[i] = Value.undef;
                     continue;
                 }
-                const int = mask_elem_val.toSignedInt();
+                const int = mask_elem_val.toSignedInt(sema.mod.getTarget());
                 const unsigned = if (int >= 0) @intCast(u32, int) else @intCast(u32, ~int);
                 if (int >= 0) {
                     values[i] = try a_val.elemValue(sema.mod, sema.arena, unsigned);
@@ -24040,6 +24074,25 @@ const CoerceOpts = struct {
     is_ret: bool = false,
     /// Should coercion to comptime_int ermit an error message.
     no_cast_to_comptime_int: bool = false,
+
+    param_src: struct {
+        func_inst: Air.Inst.Ref = .none,
+        param_i: u32 = undefined,
+
+        fn get(info: @This(), sema: *Sema) !?Module.SrcLoc {
+            if (info.func_inst == .none) return null;
+            const fn_decl = (try sema.funcDeclSrc(info.func_inst)) orelse return null;
+            const param_src = Module.paramSrc(0, sema.gpa, fn_decl, info.param_i);
+            if (param_src == .node_offset_param) {
+                return Module.SrcLoc{
+                    .file_scope = fn_decl.getFileScope(),
+                    .parent_decl_node = fn_decl.src_node,
+                    .lazy = LazySrcLoc.nodeOffset(param_src.node_offset_param),
+                };
+            }
+            return param_src.toSrcLoc(fn_decl);
+        }
+    } = .{},
 };
 
 fn coerceExtra(
@@ -24699,6 +24752,10 @@ fn coerceExtra(
             }
         }
 
+        if (try opts.param_src.get(sema)) |param_src| {
+            try sema.mod.errNoteNonLazy(param_src, msg, "parameter type declared here", .{});
+        }
+
         // TODO maybe add "cannot store an error in type '{}'" note
 
         break :msg msg;
@@ -28307,6 +28364,7 @@ fn cmpNumeric(
 
     var lhs_bits: usize = undefined;
     if (try sema.resolveMaybeUndefVal(lhs)) |lhs_val| {
+        try sema.resolveLazyValue(lhs_val);
         if (lhs_val.isUndef())
             return sema.addConstUndef(Type.bool);
         if (lhs_val.isNan()) switch (op) {
@@ -28365,6 +28423,7 @@ fn cmpNumeric(
 
     var rhs_bits: usize = undefined;
     if (try sema.resolveMaybeUndefVal(rhs)) |rhs_val| {
+        try sema.resolveLazyValue(rhs_val);
         if (rhs_val.isUndef())
             return sema.addConstUndef(Type.bool);
         if (rhs_val.isNan()) switch (op) {
@@ -29237,6 +29296,16 @@ fn resolveStructLayout(sema: *Sema, ty: Type) CompileError!void {
 
         struct_obj.status = .have_layout;
         _ = try sema.resolveTypeRequiresComptime(resolved_ty);
+
+        if (struct_obj.assumed_runtime_bits and !resolved_ty.hasRuntimeBits()) {
+            const msg = try Module.ErrorMsg.create(
+                sema.gpa,
+                struct_obj.srcLoc(sema.mod),
+                "struct layout depends on it having runtime bits",
+                .{},
+            );
+            return sema.failWithOwnedErrorMsg(msg);
+        }
     }
     // otherwise it's a tuple; no need to resolve anything
 }
@@ -29401,6 +29470,16 @@ fn resolveUnionLayout(sema: *Sema, ty: Type) CompileError!void {
     }
     union_obj.status = .have_layout;
     _ = try sema.resolveTypeRequiresComptime(resolved_ty);
+
+    if (union_obj.assumed_runtime_bits and !resolved_ty.hasRuntimeBits()) {
+        const msg = try Module.ErrorMsg.create(
+            sema.gpa,
+            union_obj.srcLoc(sema.mod),
+            "union layout depends on it having runtime bits",
+            .{},
+        );
+        return sema.failWithOwnedErrorMsg(msg);
+    }
 }
 
 // In case of querying the ABI alignment of this struct, we will ask
diff --git a/src/Zir.zig b/src/Zir.zig
index c7e1d22d22..ed425ea73e 100644
--- a/src/Zir.zig
+++ b/src/Zir.zig
@@ -519,7 +519,7 @@ pub const Inst = struct {
         /// Includes an operand as the return value.
         /// Includes a token source location.
         /// Uses the `un_tok` union field.
-        ret_tok,
+        ret_implicit,
         /// Sends control flow back to the function's callee.
         /// The return operand is `error.foo` where `foo` is given by the string.
         /// If the current function has an inferred error set, the error given by the
@@ -1256,7 +1256,7 @@ pub const Inst = struct {
                 .compile_error,
                 .ret_node,
                 .ret_load,
-                .ret_tok,
+                .ret_implicit,
                 .ret_err_value,
                 .@"unreachable",
                 .repeat,
@@ -1530,7 +1530,7 @@ pub const Inst = struct {
                 .compile_error,
                 .ret_node,
                 .ret_load,
-                .ret_tok,
+                .ret_implicit,
                 .ret_err_value,
                 .ret_ptr,
                 .ret_type,
@@ -1659,7 +1659,7 @@ pub const Inst = struct {
                 .ref = .un_tok,
                 .ret_node = .un_node,
                 .ret_load = .un_node,
-                .ret_tok = .un_tok,
+                .ret_implicit = .un_tok,
                 .ret_err_value = .str_tok,
                 .ret_err_value_code = .str_tok,
                 .ret_ptr = .node,
diff --git a/src/arch/aarch64/CodeGen.zig b/src/arch/aarch64/CodeGen.zig
index 9975e08ea9..4d541c4da7 100644
--- a/src/arch/aarch64/CodeGen.zig
+++ b/src/arch/aarch64/CodeGen.zig
@@ -6113,7 +6113,7 @@ fn genTypedValue(self: *Self, arg_tv: TypedValue) InnerError!MCValue {
             if (info.bits <= 64) {
                 const unsigned = switch (info.signedness) {
                     .signed => blk: {
-                        const signed = typed_value.val.toSignedInt();
+                        const signed = typed_value.val.toSignedInt(target);
                         break :blk @bitCast(u64, signed);
                     },
                     .unsigned => typed_value.val.toUnsignedInt(target),
diff --git a/src/arch/arm/CodeGen.zig b/src/arch/arm/CodeGen.zig
index 7a9e00b83f..257255e00c 100644
--- a/src/arch/arm/CodeGen.zig
+++ b/src/arch/arm/CodeGen.zig
@@ -6070,7 +6070,7 @@ fn genTypedValue(self: *Self, arg_tv: TypedValue) InnerError!MCValue {
             if (info.bits <= ptr_bits) {
                 const unsigned = switch (info.signedness) {
                     .signed => blk: {
-                        const signed = @intCast(i32, typed_value.val.toSignedInt());
+                        const signed = @intCast(i32, typed_value.val.toSignedInt(target));
                         break :blk @bitCast(u32, signed);
                     },
                     .unsigned => @intCast(u32, typed_value.val.toUnsignedInt(target)),
diff --git a/src/arch/sparc64/CodeGen.zig b/src/arch/sparc64/CodeGen.zig
index 9f345767de..cb5df697f5 100644
--- a/src/arch/sparc64/CodeGen.zig
+++ b/src/arch/sparc64/CodeGen.zig
@@ -3751,7 +3751,7 @@ fn genTypedValue(self: *Self, typed_value: TypedValue) InnerError!MCValue {
             if (info.bits <= 64) {
                 const unsigned = switch (info.signedness) {
                     .signed => blk: {
-                        const signed = typed_value.val.toSignedInt();
+                        const signed = typed_value.val.toSignedInt(target);
                         break :blk @bitCast(u64, signed);
                     },
                     .unsigned => typed_value.val.toUnsignedInt(target),
diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index c424c7b59d..1d24076154 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -2670,11 +2670,11 @@ fn lowerConstant(func: *CodeGen, arg_val: Value, ty: Type) InnerError!WValue {
             switch (int_info.signedness) {
                 .signed => switch (int_info.bits) {
                     0...32 => return WValue{ .imm32 = @intCast(u32, toTwosComplement(
-                        val.toSignedInt(),
+                        val.toSignedInt(target),
                         @intCast(u6, int_info.bits),
                     )) },
                     33...64 => return WValue{ .imm64 = toTwosComplement(
-                        val.toSignedInt(),
+                        val.toSignedInt(target),
                         @intCast(u7, int_info.bits),
                     ) },
                     else => unreachable,
@@ -2841,15 +2841,15 @@ fn valueAsI32(func: *const CodeGen, val: Value, ty: Type) i32 {
             }
         },
         .Int => switch (ty.intInfo(func.target).signedness) {
-            .signed => return @truncate(i32, val.toSignedInt()),
+            .signed => return @truncate(i32, val.toSignedInt(target)),
             .unsigned => return @bitCast(i32, @truncate(u32, val.toUnsignedInt(target))),
         },
         .ErrorSet => {
             const kv = func.bin_file.base.options.module.?.getErrorValue(val.getError().?) catch unreachable; // passed invalid `Value` to function
             return @bitCast(i32, kv.value);
         },
-        .Bool => return @intCast(i32, val.toSignedInt()),
-        .Pointer => return @intCast(i32, val.toSignedInt()),
+        .Bool => return @intCast(i32, val.toSignedInt(target)),
+        .Pointer => return @intCast(i32, val.toSignedInt(target)),
         else => unreachable, // Programmer called this function for an illegal type
     }
 }
diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig
index ae7cbc762d..baafdc9d1f 100644
--- a/src/arch/x86_64/CodeGen.zig
+++ b/src/arch/x86_64/CodeGen.zig
@@ -6862,7 +6862,7 @@ fn genTypedValue(self: *Self, arg_tv: TypedValue) InnerError!MCValue {
         .Int => {
             const info = typed_value.ty.intInfo(self.target.*);
             if (info.bits <= ptr_bits and info.signedness == .signed) {
-                return MCValue{ .immediate = @bitCast(u64, typed_value.val.toSignedInt()) };
+                return MCValue{ .immediate = @bitCast(u64, typed_value.val.toSignedInt(target)) };
             }
             if (!(info.bits > ptr_bits or info.signedness == .signed)) {
                 return MCValue{ .immediate = typed_value.val.toUnsignedInt(target) };
diff --git a/src/codegen.zig b/src/codegen.zig
index d6b2ed7d93..2261ba3b94 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -472,7 +472,7 @@ pub fn generateSymbol(
             if (info.bits <= 8) {
                 const x: u8 = switch (info.signedness) {
                     .unsigned => @intCast(u8, typed_value.val.toUnsignedInt(target)),
-                    .signed => @bitCast(u8, @intCast(i8, typed_value.val.toSignedInt())),
+                    .signed => @bitCast(u8, @intCast(i8, typed_value.val.toSignedInt(target))),
                 };
                 try code.append(x);
                 return Result{ .appended = {} };
@@ -501,13 +501,13 @@ pub fn generateSymbol(
                 },
                 .signed => {
                     if (info.bits <= 16) {
-                        const x = @intCast(i16, typed_value.val.toSignedInt());
+                        const x = @intCast(i16, typed_value.val.toSignedInt(target));
                         mem.writeInt(i16, try code.addManyAsArray(2), x, endian);
                     } else if (info.bits <= 32) {
-                        const x = @intCast(i32, typed_value.val.toSignedInt());
+                        const x = @intCast(i32, typed_value.val.toSignedInt(target));
                         mem.writeInt(i32, try code.addManyAsArray(4), x, endian);
                     } else {
-                        const x = typed_value.val.toSignedInt();
+                        const x = typed_value.val.toSignedInt(target);
                         mem.writeInt(i64, try code.addManyAsArray(8), x, endian);
                     }
                 },
@@ -549,13 +549,13 @@ pub fn generateSymbol(
                 },
                 .signed => {
                     if (info.bits <= 16) {
-                        const x = @intCast(i16, int_val.toSignedInt());
+                        const x = @intCast(i16, int_val.toSignedInt(target));
                         mem.writeInt(i16, try code.addManyAsArray(2), x, endian);
                     } else if (info.bits <= 32) {
-                        const x = @intCast(i32, int_val.toSignedInt());
+                        const x = @intCast(i32, int_val.toSignedInt(target));
                         mem.writeInt(i32, try code.addManyAsArray(4), x, endian);
                     } else {
-                        const x = int_val.toSignedInt();
+                        const x = int_val.toSignedInt(target);
                         mem.writeInt(i64, try code.addManyAsArray(8), x, endian);
                     }
                 },
diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 6215a11e6f..3fd1effc21 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -8932,7 +8932,7 @@ pub const FuncGen = struct {
             if (elem.isUndef()) {
                 val.* = llvm_i32.getUndef();
             } else {
-                const int = elem.toSignedInt();
+                const int = elem.toSignedInt(self.dg.module.getTarget());
                 const unsigned = if (int >= 0) @intCast(u32, int) else @intCast(u32, ~int + a_len);
                 val.* = llvm_i32.constInt(unsigned, .False);
             }
diff --git a/src/codegen/spirv.zig b/src/codegen/spirv.zig
index ada3918baf..bd0c8bc53c 100644
--- a/src/codegen/spirv.zig
+++ b/src/codegen/spirv.zig
@@ -360,7 +360,7 @@ pub const DeclGen = struct {
 
                 // Note, value is required to be sign-extended, so we don't need to mask off the upper bits.
                 // See https://www.khronos.org/registry/SPIR-V/specs/unified1/SPIRV.html#Literal
-                var int_bits = if (ty.isSignedInt()) @bitCast(u64, val.toSignedInt()) else val.toUnsignedInt(target);
+                var int_bits = if (ty.isSignedInt()) @bitCast(u64, val.toSignedInt(target)) else val.toUnsignedInt(target);
 
                 const value: spec.LiteralContextDependentNumber = switch (backing_bits) {
                     1...32 => .{ .uint32 = @truncate(u32, int_bits) },
@@ -763,7 +763,7 @@ pub const DeclGen = struct {
             if (elem.isUndef()) {
                 self.func.body.writeOperand(spec.LiteralInteger, 0xFFFF_FFFF);
             } else {
-                const int = elem.toSignedInt();
+                const int = elem.toSignedInt(self.getTarget());
                 const unsigned = if (int >= 0) @intCast(u32, int) else @intCast(u32, ~int + a_len);
                 self.func.body.writeOperand(spec.LiteralInteger, unsigned);
             }
diff --git a/src/link/Dwarf.zig b/src/link/Dwarf.zig
index 63ccb57e77..54f4300098 100644
--- a/src/link/Dwarf.zig
+++ b/src/link/Dwarf.zig
@@ -410,7 +410,7 @@ pub const DeclState = struct {
                         // See https://github.com/ziglang/zig/issues/645
                         var int_buffer: Value.Payload.U64 = undefined;
                         const field_int_val = value.enumToInt(ty, &int_buffer);
-                        break :value @bitCast(u64, field_int_val.toSignedInt());
+                        break :value @bitCast(u64, field_int_val.toSignedInt(target));
                     } else @intCast(u64, field_i);
                     mem.writeInt(u64, dbg_info_buffer.addManyAsArrayAssumeCapacity(8), value, target_endian);
                 }
diff --git a/src/print_zir.zig b/src/print_zir.zig
index 9135c22010..542f0e977d 100644
--- a/src/print_zir.zig
+++ b/src/print_zir.zig
@@ -235,7 +235,7 @@ const Writer = struct {
             => try self.writeUnNode(stream, inst),
 
             .ref,
-            .ret_tok,
+            .ret_implicit,
             .closure_capture,
             .switch_capture_tag,
             => try self.writeUnTok(stream, inst),
diff --git a/src/type.zig b/src/type.zig
index 21cfdf9d73..d36bd285f8 100644
--- a/src/type.zig
+++ b/src/type.zig
@@ -160,6 +160,17 @@ pub const Type = extern union {
         }
     }
 
+    pub fn baseZigTypeTag(self: Type) std.builtin.TypeId {
+        return switch (self.zigTypeTag()) {
+            .ErrorUnion => self.errorUnionPayload().baseZigTypeTag(),
+            .Optional => {
+                var buf: Payload.ElemType = undefined;
+                return self.optionalChild(&buf).baseZigTypeTag();
+            },
+            else => |t| t,
+        };
+    }
+
     pub fn isSelfComparable(ty: Type, is_equality_cmp: bool) bool {
         return switch (ty.zigTypeTag()) {
             .Int,
@@ -2459,6 +2470,7 @@ pub const Type = extern union {
                 if (struct_obj.status == .field_types_wip) {
                     // In this case, we guess that hasRuntimeBits() for this type is true,
                     // and then later if our guess was incorrect, we emit a compile error.
+                    struct_obj.assumed_runtime_bits = true;
                     return true;
                 }
                 switch (strat) {
@@ -2491,6 +2503,12 @@ pub const Type = extern union {
 
             .@"union" => {
                 const union_obj = ty.castTag(.@"union").?.data;
+                if (union_obj.status == .field_types_wip) {
+                    // In this case, we guess that hasRuntimeBits() for this type is true,
+                    // and then later if our guess was incorrect, we emit a compile error.
+                    union_obj.assumed_runtime_bits = true;
+                    return true;
+                }
                 switch (strat) {
                     .sema => |sema| _ = try sema.resolveTypeFields(ty),
                     .eager => assert(union_obj.haveFieldTypes()),
@@ -3027,8 +3045,9 @@ pub const Type = extern union {
                 const struct_obj = ty.castTag(.@"struct").?.data;
                 if (opt_sema) |sema| {
                     if (struct_obj.status == .field_types_wip) {
-                        // We'll guess "pointer-aligned" and if we guess wrong, emit
-                        // a compile error later.
+                        // We'll guess "pointer-aligned", if the struct has an
+                        // underaligned pointer field then some allocations
+                        // might require explicit alignment.
                         return AbiAlignmentAdvanced{ .scalar = @divExact(target.cpu.arch.ptrBitWidth(), 8) };
                     }
                     _ = try sema.resolveTypeFields(ty);
@@ -3153,8 +3172,9 @@ pub const Type = extern union {
         };
         if (opt_sema) |sema| {
             if (union_obj.status == .field_types_wip) {
-                // We'll guess "pointer-aligned" and if we guess wrong, emit
-                // a compile error later.
+                // We'll guess "pointer-aligned", if the union has an
+                // underaligned pointer field then some allocations
+                // might require explicit alignment.
                 return AbiAlignmentAdvanced{ .scalar = @divExact(target.cpu.arch.ptrBitWidth(), 8) };
             }
             _ = try sema.resolveTypeFields(ty);
@@ -5234,7 +5254,12 @@ pub const Type = extern union {
             .@"struct" => {
                 const struct_obj = ty.castTag(.@"struct").?.data;
                 switch (struct_obj.requires_comptime) {
-                    .wip, .unknown => unreachable, // This function asserts types already resolved.
+                    .wip, .unknown => {
+                        // Return false to avoid incorrect dependency loops.
+                        // This will be handled correctly once merged with
+                        // `Sema.typeRequiresComptime`.
+                        return false;
+                    },
                     .no => return false,
                     .yes => return true,
                 }
@@ -5243,7 +5268,12 @@ pub const Type = extern union {
             .@"union", .union_safety_tagged, .union_tagged => {
                 const union_obj = ty.cast(Type.Payload.Union).?.data;
                 switch (union_obj.requires_comptime) {
-                    .wip, .unknown => unreachable, // This function asserts types already resolved.
+                    .wip, .unknown => {
+                        // Return false to avoid incorrect dependency loops.
+                        // This will be handled correctly once merged with
+                        // `Sema.typeRequiresComptime`.
+                        return false;
+                    },
                     .no => return false,
                     .yes => return true,
                 }
@@ -6472,8 +6502,16 @@ pub const Type = extern union {
         // type, we change it to 0 here. If this causes an assertion trip because the
         // pointee type needs to be resolved more, that needs to be done before calling
         // this ptr() function.
-        if (d.@"align" != 0 and d.@"align" == d.pointee_type.abiAlignment(target)) {
-            d.@"align" = 0;
+        if (d.@"align" != 0) canonicalize: {
+            if (d.pointee_type.castTag(.@"struct")) |struct_ty| {
+                if (!struct_ty.data.haveLayout()) break :canonicalize;
+            }
+            if (d.pointee_type.cast(Payload.Union)) |union_ty| {
+                if (!union_ty.data.haveLayout()) break :canonicalize;
+            }
+            if (d.@"align" == d.pointee_type.abiAlignment(target)) {
+                d.@"align" = 0;
+            }
         }
 
         // Canonicalize host_size. If it matches the bit size of the pointee type,
diff --git a/src/value.zig b/src/value.zig
index be643f65a3..d3035946f9 100644
--- a/src/value.zig
+++ b/src/value.zig
@@ -187,7 +187,7 @@ pub const Value = extern union {
         bound_fn,
         /// The ABI alignment of the payload type.
         lazy_align,
-        /// The ABI alignment of the payload type.
+        /// The ABI size of the payload type.
         lazy_size,
 
         pub const last_no_payload_tag = Tag.empty_array;
@@ -1201,8 +1201,8 @@ pub const Value = extern union {
     }
 
     /// Asserts the value is an integer and it fits in a i64
-    pub fn toSignedInt(self: Value) i64 {
-        switch (self.tag()) {
+    pub fn toSignedInt(val: Value, target: Target) i64 {
+        switch (val.tag()) {
             .zero,
             .bool_false,
             .the_only_possible_value, // i0, u0
@@ -1212,10 +1212,19 @@ pub const Value = extern union {
             .bool_true,
             => return 1,
 
-            .int_u64 => return @intCast(i64, self.castTag(.int_u64).?.data),
-            .int_i64 => return self.castTag(.int_i64).?.data,
-            .int_big_positive => return self.castTag(.int_big_positive).?.asBigInt().to(i64) catch unreachable,
-            .int_big_negative => return self.castTag(.int_big_negative).?.asBigInt().to(i64) catch unreachable,
+            .int_u64 => return @intCast(i64, val.castTag(.int_u64).?.data),
+            .int_i64 => return val.castTag(.int_i64).?.data,
+            .int_big_positive => return val.castTag(.int_big_positive).?.asBigInt().to(i64) catch unreachable,
+            .int_big_negative => return val.castTag(.int_big_negative).?.asBigInt().to(i64) catch unreachable,
+
+            .lazy_align => {
+                const ty = val.castTag(.lazy_align).?.data;
+                return @intCast(i64, ty.abiAlignment(target));
+            },
+            .lazy_size => {
+                const ty = val.castTag(.lazy_size).?.data;
+                return @intCast(i64, ty.abiSize(target));
+            },
 
             .undef => unreachable,
             else => unreachable,
diff --git a/test/behavior.zig b/test/behavior.zig
index 4e959fcf7d..3b6eb9c6ef 100644
--- a/test/behavior.zig
+++ b/test/behavior.zig
@@ -90,6 +90,7 @@ test {
     _ = @import("behavior/bugs/12430.zig");
     _ = @import("behavior/bugs/12486.zig");
     _ = @import("behavior/bugs/12488.zig");
+    _ = @import("behavior/bugs/12498.zig");
     _ = @import("behavior/bugs/12551.zig");
     _ = @import("behavior/bugs/12644.zig");
     _ = @import("behavior/bugs/12680.zig");
diff --git a/test/behavior/bugs/12498.zig b/test/behavior/bugs/12498.zig
new file mode 100644
index 0000000000..3e4bafc2db
--- /dev/null
+++ b/test/behavior/bugs/12498.zig
@@ -0,0 +1,8 @@
+const std = @import("std");
+const expect = std.testing.expect;
+
+const S = struct { a: usize };
+test "lazy abi size used in comparison" {
+    var rhs: i32 = 100;
+    try expect(@sizeOf(S) < rhs);
+}
diff --git a/test/behavior/struct.zig b/test/behavior/struct.zig
index a74b9fdd53..1807b7a447 100644
--- a/test/behavior/struct.zig
+++ b/test/behavior/struct.zig
@@ -1406,3 +1406,15 @@ test "address of zero-bit field is equal to address of only field" {
         try std.testing.expectEqual(&a, a_ptr);
     }
 }
+
+test "struct field has a pointer to an aligned version of itself" {
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
+
+    const E = struct {
+        next: *align(1) @This(),
+    };
+    var e: E = undefined;
+    e = .{ .next = &e };
+
+    try expect(&e == e.next);
+}
diff --git a/test/cases/aarch64-macos/hello_world_with_updates.1.zig b/test/cases/aarch64-macos/hello_world_with_updates.1.zig
index e18a4c6a1e..dcf18bbf87 100644
--- a/test/cases/aarch64-macos/hello_world_with_updates.1.zig
+++ b/test/cases/aarch64-macos/hello_world_with_updates.1.zig
@@ -2,5 +2,5 @@ pub export fn main() noreturn {}
 
 // error
 //
-// :1:32: error: function declared 'noreturn' returns
-// :1:22: note: 'noreturn' declared here
+// :1:22: error: function declared 'noreturn' implicitly returns
+// :1:32: note: control flow reaches end of body here
diff --git a/test/cases/compile_errors/calling_var_args_extern_function_passing_array_instead_of_pointer.zig b/test/cases/compile_errors/calling_var_args_extern_function_passing_array_instead_of_pointer.zig
index 846a5ff81a..c9e2e2e5eb 100644
--- a/test/cases/compile_errors/calling_var_args_extern_function_passing_array_instead_of_pointer.zig
+++ b/test/cases/compile_errors/calling_var_args_extern_function_passing_array_instead_of_pointer.zig
@@ -8,3 +8,4 @@ pub extern fn foo(format: *const u8, ...) void;
 // target=native
 //
 // :2:16: error: expected type '*const u8', found '[5:0]u8'
+// :4:27: note: parameter type declared here
diff --git a/test/cases/compile_errors/casting_bit_offset_pointer_to_regular_pointer.zig b/test/cases/compile_errors/casting_bit_offset_pointer_to_regular_pointer.zig
index 132627557e..7fd38280c6 100644
--- a/test/cases/compile_errors/casting_bit_offset_pointer_to_regular_pointer.zig
+++ b/test/cases/compile_errors/casting_bit_offset_pointer_to_regular_pointer.zig
@@ -21,3 +21,4 @@ export fn entry() usize { return @sizeOf(@TypeOf(&foo)); }
 // :8:16: error: expected type '*const u3', found '*align(0:3:1) const u3'
 // :8:16: note: pointer host size '1' cannot cast into pointer host size '0'
 // :8:16: note: pointer bit offset '3' cannot cast into pointer bit offset '0'
+// :11:11: note: parameter type declared here
diff --git a/test/cases/compile_errors/closure_get_in_param_ty_instantiate_incorrectly.zig b/test/cases/compile_errors/closure_get_in_param_ty_instantiate_incorrectly.zig
index dc533442fb..8855755ec1 100644
--- a/test/cases/compile_errors/closure_get_in_param_ty_instantiate_incorrectly.zig
+++ b/test/cases/compile_errors/closure_get_in_param_ty_instantiate_incorrectly.zig
@@ -22,3 +22,4 @@ pub export fn entry() void {
 // target=native
 //
 // :17:25: error: expected type 'u32', found 'type'
+// :3:21: note: parameter type declared here
diff --git a/test/cases/compile_errors/control_reaches_end_of_non-void_function.zig b/test/cases/compile_errors/control_reaches_end_of_non-void_function.zig
deleted file mode 100644
index c92b6b0927..0000000000
--- a/test/cases/compile_errors/control_reaches_end_of_non-void_function.zig
+++ /dev/null
@@ -1,9 +0,0 @@
-fn a() i32 {}
-export fn entry() void { _ = a(); }
-
-// error
-// backend=stage2
-// target=native
-//
-// :1:13: error: expected type 'i32', found 'void'
-// :1:8: note: function return type declared here
diff --git a/test/cases/compile_errors/disallow_coercion_from_non-null-terminated_pointer_to_null-terminated_pointer.zig b/test/cases/compile_errors/disallow_coercion_from_non-null-terminated_pointer_to_null-terminated_pointer.zig
index 0074c26de7..3670def4ee 100644
--- a/test/cases/compile_errors/disallow_coercion_from_non-null-terminated_pointer_to_null-terminated_pointer.zig
+++ b/test/cases/compile_errors/disallow_coercion_from_non-null-terminated_pointer_to_null-terminated_pointer.zig
@@ -11,3 +11,4 @@ pub export fn entry() void {
 //
 // :5:14: error: expected type '[*:0]const u8', found '[*]const u8'
 // :5:14: note: destination pointer requires '0' sentinel
+// :1:20: note: parameter type declared here
diff --git a/test/cases/compile_errors/double_pointer_to_anyopaque_pointer.zig b/test/cases/compile_errors/double_pointer_to_anyopaque_pointer.zig
index 6aa9618dbd..c7e54738d1 100644
--- a/test/cases/compile_errors/double_pointer_to_anyopaque_pointer.zig
+++ b/test/cases/compile_errors/double_pointer_to_anyopaque_pointer.zig
@@ -24,5 +24,6 @@ pub export fn entry3() void {
 // :4:35: note: cannot implicitly cast double pointer '*const *const usize' to anyopaque pointer '*const anyopaque'
 // :9:10: error: expected type '?*anyopaque', found '*[*:0]u8'
 // :9:10: note: cannot implicitly cast double pointer '*[*:0]u8' to anyopaque pointer '?*anyopaque'
+// :11:12: note: parameter type declared here
 // :15:35: error: expected type '*const anyopaque', found '*?*usize'
 // :15:35: note: cannot implicitly cast double pointer '*?*usize' to anyopaque pointer '*const anyopaque'
diff --git a/test/cases/compile_errors/implicitly_increasing_pointer_alignment.zig b/test/cases/compile_errors/implicitly_increasing_pointer_alignment.zig
index b9a9fb2faf..13adba1b91 100644
--- a/test/cases/compile_errors/implicitly_increasing_pointer_alignment.zig
+++ b/test/cases/compile_errors/implicitly_increasing_pointer_alignment.zig
@@ -18,3 +18,4 @@ fn bar(x: *u32) void {
 //
 // :8:9: error: expected type '*u32', found '*align(1) u32'
 // :8:9: note: pointer alignment '1' cannot cast into pointer alignment '4'
+// :11:11: note: parameter type declared here
diff --git a/test/cases/compile_errors/invalid_compare_string.zig b/test/cases/compile_errors/invalid_compare_string.zig
new file mode 100644
index 0000000000..a5c7f041a5
--- /dev/null
+++ b/test/cases/compile_errors/invalid_compare_string.zig
@@ -0,0 +1,29 @@
+comptime {
+    var a = "foo";
+    if (a == "foo") unreachable;
+}
+comptime {
+    var a = "foo";
+    if (a == ("foo")) unreachable; // intentionally allow
+}
+comptime {
+    var a = "foo";
+    switch (a) {
+        "foo" => unreachable,
+        else => {},
+    }
+}
+comptime {
+    var a = "foo";
+    switch (a) {
+        ("foo") => unreachable, // intentionally allow
+        else => {},
+    }
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:11: error: cannot compare strings with ==
+// :12:9: error: cannot switch on strings
diff --git a/test/cases/compile_errors/invalid_dependency_on_struct_size.zig b/test/cases/compile_errors/invalid_dependency_on_struct_size.zig
new file mode 100644
index 0000000000..02ea7e2710
--- /dev/null
+++ b/test/cases/compile_errors/invalid_dependency_on_struct_size.zig
@@ -0,0 +1,19 @@
+comptime {
+    const S = struct {
+        const Foo = struct {
+            y: Bar,
+        };
+        const Bar = struct {
+            y: if (@sizeOf(Foo) == 0) u64 else void,
+        };
+    };
+
+    _ = @sizeOf(S.Foo) + 1;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :6:21: error: struct layout depends on it having runtime bits
+// :4:13: note: while checking this field
diff --git a/test/cases/compile_errors/missing_parameter_name.zig b/test/cases/compile_errors/missing_parameter_name.zig
new file mode 100644
index 0000000000..3e576a1a6d
--- /dev/null
+++ b/test/cases/compile_errors/missing_parameter_name.zig
@@ -0,0 +1,19 @@
+fn f2(u64) u64 {
+    return x;
+}
+fn f3(*x) u64 {
+    return x;
+}
+fn f1(x) u64 {
+    return x;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :1:7: error: missing parameter name
+// :4:7: error: missing parameter name
+// :7:7: error: missing parameter name or type
+// :7:7: note: if this is a name, annotate its type 'x: T'
+// :7:7: note: if this is a type, give it a name '<name>: x'
diff --git a/test/cases/compile_errors/pass_const_ptr_to_mutable_ptr_fn.zig b/test/cases/compile_errors/pass_const_ptr_to_mutable_ptr_fn.zig
index 39c55870f1..fd24b58f55 100644
--- a/test/cases/compile_errors/pass_const_ptr_to_mutable_ptr_fn.zig
+++ b/test/cases/compile_errors/pass_const_ptr_to_mutable_ptr_fn.zig
@@ -16,3 +16,4 @@ export fn entry() usize { return @sizeOf(@TypeOf(&foo)); }
 //
 // :4:19: error: expected type '*[]const u8', found '*const []const u8'
 // :4:19: note: cast discards const qualifier
+// :6:14: note: parameter type declared here
diff --git a/test/cases/compile_errors/struct_init_passed_to_type_param.zig b/test/cases/compile_errors/struct_init_passed_to_type_param.zig
index b00c27986f..01906ac613 100644
--- a/test/cases/compile_errors/struct_init_passed_to_type_param.zig
+++ b/test/cases/compile_errors/struct_init_passed_to_type_param.zig
@@ -12,3 +12,4 @@ export const value = hi(MyStruct{ .x = 12 });
 //
 // :7:33: error: expected type 'type', found 'tmp.MyStruct'
 // :1:18: note: struct declared here
+// :3:19: note: parameter type declared here
diff --git a/test/cases/compile_errors/struct_type_mismatch_in_arg.zig b/test/cases/compile_errors/struct_type_mismatch_in_arg.zig
new file mode 100644
index 0000000000..a52bdfab6c
--- /dev/null
+++ b/test/cases/compile_errors/struct_type_mismatch_in_arg.zig
@@ -0,0 +1,18 @@
+const Foo = struct { i: i32 };
+const Bar = struct { j: i32 };
+
+pub fn helper(_: Foo, _: Bar) void { }
+
+comptime {
+    helper(Bar { .j = 10 }, Bar { .j = 10 });
+    helper(Bar { .i = 10 }, Bar { .j = 10 });
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :7:16: error: expected type 'tmp.Foo', found 'tmp.Bar'
+// :1:13: note: struct declared here
+// :2:13: note: struct declared here
+// :4:18: note: parameter type declared here
diff --git a/test/cases/compile_errors/switch_on_slice.zig b/test/cases/compile_errors/switch_on_slice.zig
index b4644b132c..c2b28f67ab 100644
--- a/test/cases/compile_errors/switch_on_slice.zig
+++ b/test/cases/compile_errors/switch_on_slice.zig
@@ -1,7 +1,7 @@
 pub export fn entry() void {
     var a: [:0]const u8 = "foo";
     switch (a) {
-        "--version", "version" => unreachable,
+        ("--version"), ("version") => unreachable,
         else => {},
     }
 }
diff --git a/test/cases/compile_errors/type_error_in_implicit_return.zig b/test/cases/compile_errors/type_error_in_implicit_return.zig
new file mode 100644
index 0000000000..8c8d498c97
--- /dev/null
+++ b/test/cases/compile_errors/type_error_in_implicit_return.zig
@@ -0,0 +1,17 @@
+fn f1(x: bool) u32 {
+    if (x) return 1;
+}
+fn f2() noreturn {}
+pub export fn entry() void {
+    _ = f1(true);
+    _ = f2();
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :1:16: error: function with non-void return type 'u32' implicitly returns
+// :3:1: note: control flow reaches end of body here
+// :4:9: error: function declared 'noreturn' implicitly returns
+// :4:19: note: control flow reaches end of body here
diff --git a/test/cases/compile_errors/wrong_pointer_coerced_to_pointer_to_opaque_{}.zig b/test/cases/compile_errors/wrong_pointer_coerced_to_pointer_to_opaque_{}.zig
index e22c285cb0..a050eb6a4c 100644
--- a/test/cases/compile_errors/wrong_pointer_coerced_to_pointer_to_opaque_{}.zig
+++ b/test/cases/compile_errors/wrong_pointer_coerced_to_pointer_to_opaque_{}.zig
@@ -12,3 +12,4 @@ export fn foo() void {
 // :5:9: error: expected type '*tmp.Derp', found '*anyopaque'
 // :5:9: note: pointer type child 'anyopaque' cannot cast into pointer type child 'tmp.Derp'
 // :1:14: note: opaque declared here
+// :2:18: note: parameter type declared here
diff --git a/test/cases/x86_64-linux/hello_world_with_updates.1.zig b/test/cases/x86_64-linux/hello_world_with_updates.1.zig
index 1f1a6a9682..dcf18bbf87 100644
--- a/test/cases/x86_64-linux/hello_world_with_updates.1.zig
+++ b/test/cases/x86_64-linux/hello_world_with_updates.1.zig
@@ -1,6 +1,6 @@
-pub export fn _start() noreturn {}
+pub export fn main() noreturn {}
 
 // error
 //
-// :1:34: error: function declared 'noreturn' returns
-// :1:24: note: 'noreturn' declared here
+// :1:22: error: function declared 'noreturn' implicitly returns
+// :1:32: note: control flow reaches end of body here
diff --git a/test/cases/x86_64-macos/hello_world_with_updates.1.zig b/test/cases/x86_64-macos/hello_world_with_updates.1.zig
index e18a4c6a1e..dcf18bbf87 100644
--- a/test/cases/x86_64-macos/hello_world_with_updates.1.zig
+++ b/test/cases/x86_64-macos/hello_world_with_updates.1.zig
@@ -2,5 +2,5 @@ pub export fn main() noreturn {}
 
 // error
 //
-// :1:32: error: function declared 'noreturn' returns
-// :1:22: note: 'noreturn' declared here
+// :1:22: error: function declared 'noreturn' implicitly returns
+// :1:32: note: control flow reaches end of body here
diff --git a/test/cases/x86_64-windows/hello_world_with_updates.1.zig b/test/cases/x86_64-windows/hello_world_with_updates.1.zig
index e18a4c6a1e..dcf18bbf87 100644
--- a/test/cases/x86_64-windows/hello_world_with_updates.1.zig
+++ b/test/cases/x86_64-windows/hello_world_with_updates.1.zig
@@ -2,5 +2,5 @@ pub export fn main() noreturn {}
 
 // error
 //
-// :1:32: error: function declared 'noreturn' returns
-// :1:22: note: 'noreturn' declared here
+// :1:22: error: function declared 'noreturn' implicitly returns
+// :1:32: note: control flow reaches end of body here