Merge pull request #2147 from emekoi/fix1940

added error for implicit cast from *const T to *[1]T.

src/ir.cpp

@@ -11090,6 +11090,7 @@ static IrInstruction *ir_analyze_ptr_to_array(IrAnalyze *ira, IrInstruction *sou
     Error err;
     if ((err = type_resolve(ira->codegen, target->value.type->data.pointer.child_type, ResolveStatusAlignmentKnown)))
         return ira->codegen->invalid_instruction;
+    assert((wanted_type->data.pointer.is_const && target->value.type->data.pointer.is_const) || !target->value.type->data.pointer.is_const);
     wanted_type = adjust_ptr_align(ira->codegen, wanted_type, get_ptr_align(ira->codegen, target->value.type));
     ZigType *array_type = wanted_type->data.pointer.child_type;
     assert(array_type->id == ZigTypeIdArray);
@@ -11651,7 +11652,11 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
         if (array_type->id == ZigTypeIdArray && array_type->data.array.len == 1 &&
             types_match_const_cast_only(ira, array_type->data.array.child_type,
             actual_type->data.pointer.child_type, source_node,
-            !wanted_type->data.pointer.is_const).id == ConstCastResultIdOk)
+            !wanted_type->data.pointer.is_const).id == ConstCastResultIdOk &&
+            // This should be the job of `types_match_const_cast_only`
+            // but `types_match_const_cast_only` only gets info for child_types
+            ((wanted_type->data.pointer.is_const && actual_type->data.pointer.is_const) ||
+            !actual_type->data.pointer.is_const))
         {
             if ((err = type_resolve(ira->codegen, wanted_type->data.pointer.child_type,
                             ResolveStatusAlignmentKnown)))

std/event/loop.zig

@@ -263,7 +263,7 @@ pub const Loop = struct {
                         .next = undefined,
                     };
                     self.available_eventfd_resume_nodes.push(eventfd_node);
-                    const kevent_array = (*[1]posix.Kevent)(&eventfd_node.data.kevent);
+                    const kevent_array = (*const [1]posix.Kevent)(&eventfd_node.data.kevent);
                     _ = try os.bsdKEvent(self.os_data.kqfd, kevent_array, empty_kevs, null);
                     eventfd_node.data.kevent.flags = posix.EV_CLEAR | posix.EV_ENABLE;
                     eventfd_node.data.kevent.fflags = posix.NOTE_TRIGGER;
@@ -279,7 +279,7 @@ pub const Loop = struct {
                     .data = 0,
                     .udata = @ptrToInt(&self.final_resume_node),
                 };
-                const final_kev_arr = (*[1]posix.Kevent)(&self.os_data.final_kevent);
+                const final_kev_arr = (*const [1]posix.Kevent)(&self.os_data.final_kevent);
                 _ = try os.bsdKEvent(self.os_data.kqfd, final_kev_arr, empty_kevs, null);
                 self.os_data.final_kevent.flags = posix.EV_ENABLE;
                 self.os_data.final_kevent.fflags = posix.NOTE_TRIGGER;
@@ -472,7 +472,7 @@ pub const Loop = struct {
             .data = 0,
             .udata = @ptrToInt(&resume_node.base),
         };
-        const kevent_array = (*[1]posix.Kevent)(&kev);
+        const kevent_array = (*const [1]posix.Kevent)(&kev);
         const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
         _ = try os.bsdKEvent(self.os_data.kqfd, kevent_array, empty_kevs, null);
     }
@@ -486,7 +486,7 @@ pub const Loop = struct {
             .data = 0,
             .udata = 0,
         };
-        const kevent_array = (*[1]posix.Kevent)(&kev);
+        const kevent_array = (*const [1]posix.Kevent)(&kev);
         const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
         _ = os.bsdKEvent(self.os_data.kqfd, kevent_array, empty_kevs, null) catch undefined;
         self.finishOneEvent();
@@ -502,7 +502,7 @@ pub const Loop = struct {
             eventfd_node.base.handle = next_tick_node.data;
             switch (builtin.os) {
                 builtin.Os.macosx, builtin.Os.freebsd, builtin.Os.netbsd => {
-                    const kevent_array = (*[1]posix.Kevent)(&eventfd_node.kevent);
+                    const kevent_array = (*const [1]posix.Kevent)(&eventfd_node.kevent);
                     const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
                     _ = os.bsdKEvent(self.os_data.kqfd, kevent_array, empty_kevs, null) catch {
                         self.next_tick_queue.unget(next_tick_node);
@@ -631,7 +631,7 @@ pub const Loop = struct {
                 },
                 builtin.Os.macosx, builtin.Os.freebsd, builtin.Os.netbsd => {
                     self.posixFsRequest(&self.os_data.fs_end_request);
-                    const final_kevent = (*[1]posix.Kevent)(&self.os_data.final_kevent);
+                    const final_kevent = (*const [1]posix.Kevent)(&self.os_data.final_kevent);
                     const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
                     // cannot fail because we already added it and this just enables it
                     _ = os.bsdKEvent(self.os_data.kqfd, final_kevent, empty_kevs, null) catch unreachable;
@@ -751,7 +751,7 @@ pub const Loop = struct {
         self.os_data.fs_queue.put(request_node);
         switch (builtin.os) {
             builtin.Os.macosx, builtin.Os.freebsd, builtin.Os.netbsd => {
-                const fs_kevs = (*[1]posix.Kevent)(&self.os_data.fs_kevent_wake);
+                const fs_kevs = (*const [1]posix.Kevent)(&self.os_data.fs_kevent_wake);
                 const empty_kevs = ([*]posix.Kevent)(undefined)[0..0];
                 _ = os.bsdKEvent(self.os_data.fs_kqfd, fs_kevs, empty_kevs, null) catch unreachable;
             },
@@ -821,7 +821,7 @@ pub const Loop = struct {
                     }
                 },
                 builtin.Os.macosx, builtin.Os.freebsd, builtin.Os.netbsd => {
-                    const fs_kevs = (*[1]posix.Kevent)(&self.os_data.fs_kevent_wait);
+                    const fs_kevs = (*const [1]posix.Kevent)(&self.os_data.fs_kevent_wait);
                     var out_kevs: [1]posix.Kevent = undefined;
                     _ = os.bsdKEvent(self.os_data.fs_kqfd, fs_kevs, out_kevs[0..], null) catch unreachable;
                 },

std/fmt.zig

@@ -375,7 +375,7 @@ pub fn formatAsciiChar(
     comptime Errors: type,
     output: fn (@typeOf(context), []const u8) Errors!void,
 ) Errors!void {
-    return output(context, (*[1]u8)(&c)[0..]);
+    return output(context, (*const [1]u8)(&c)[0..]);
 }
 
 pub fn formatBuf(
@@ -390,7 +390,7 @@ pub fn formatBuf(
     var leftover_padding = if (width > buf.len) (width - buf.len) else return;
     const pad_byte: u8 = ' ';
     while (leftover_padding > 0) : (leftover_padding -= 1) {
-        try output(context, (*[1]u8)(&pad_byte)[0..1]);
+        try output(context, (*const [1]u8)(&pad_byte)[0..1]);
     }
 }
 
@@ -705,7 +705,7 @@ fn formatIntSigned(
     const uint = @IntType(false, @typeOf(value).bit_count);
     if (value < 0) {
         const minus_sign: u8 = '-';
-        try output(context, (*[1]u8)(&minus_sign)[0..]);
+        try output(context, (*const [1]u8)(&minus_sign)[0..]);
         const new_value = @intCast(uint, -(value + 1)) + 1;
         const new_width = if (width == 0) 0 else (width - 1);
         return formatIntUnsigned(new_value, base, uppercase, new_width, context, Errors, output);
@@ -713,7 +713,7 @@ fn formatIntSigned(
         return formatIntUnsigned(@intCast(uint, value), base, uppercase, width, context, Errors, output);
     } else {
         const plus_sign: u8 = '+';
-        try output(context, (*[1]u8)(&plus_sign)[0..]);
+        try output(context, (*const [1]u8)(&plus_sign)[0..]);
         const new_value = @intCast(uint, value);
         const new_width = if (width == 0) 0 else (width - 1);
         return formatIntUnsigned(new_value, base, uppercase, new_width, context, Errors, output);
@@ -751,7 +751,7 @@ fn formatIntUnsigned(
         const zero_byte: u8 = '0';
         var leftover_padding = padding - index;
         while (true) {
-            try output(context, (*[1]u8)(&zero_byte)[0..]);
+            try output(context, (*const [1]u8)(&zero_byte)[0..]);
             leftover_padding -= 1;
             if (leftover_padding == 0) break;
         }

std/io.zig

@@ -227,12 +227,12 @@ pub fn OutStream(comptime WriteError: type) type {
         }
 
         pub fn writeByte(self: *Self, byte: u8) Error!void {
-            const slice = (*[1]u8)(&byte)[0..];
+            const slice = (*const [1]u8)(&byte)[0..];
             return self.writeFn(self, slice);
         }
 
         pub fn writeByteNTimes(self: *Self, byte: u8, n: usize) Error!void {
-            const slice = (*[1]u8)(&byte)[0..];
+            const slice = (*const [1]u8)(&byte)[0..];
             var i: usize = 0;
             while (i < n) : (i += 1) {
                 try self.writeFn(self, slice);

test/compile_errors.zig

@@ -5869,4 +5869,27 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         \\    comptime testCompileLog(Bar{.X = 123});
         \\}
     , "tmp.zig:6:5: error: found compile log statement");
+
+    cases.add(
+        "attempted implicit cast from *const T to *[1]T",
+        \\export fn entry(byte: u8) void {
+        \\    const w: i32 = 1234;
+        \\    var x: *const i32 = &w;
+        \\    var y: *[1]i32 = x;
+        \\    y[0] += 1;
+        \\}
+    ,
+        "tmp.zig:4:22: error: expected type '*[1]i32', found '*const i32'",
+        "tmp.zig:4:22: note: pointer type child 'i32' cannot cast into pointer type child '[1]i32'",
+    );
+
+    cases.add(
+        "attempted implicit cast from *const T to []T",
+        \\export fn entry() void {
+        \\    const u: u32 = 42;
+        \\    const x: []u32 = &u;
+        \\}
+    ,
+        "tmp.zig:3:23: error: expected type '[]u32', found '*const u32'",
+    );
 }

test/stage1/behavior/align.zig

@@ -60,7 +60,7 @@ fn addUnaligned(a: *align(1) const u32, b: *align(1) const u32) u32 {
 test "implicitly decreasing slice alignment" {
     const a: u32 align(4) = 3;
     const b: u32 align(8) = 4;
-    expect(addUnalignedSlice((*[1]u32)(&a)[0..], (*[1]u32)(&b)[0..]) == 7);
+    expect(addUnalignedSlice((*const [1]u32)(&a)[0..], (*const [1]u32)(&b)[0..]) == 7);
 }
 fn addUnalignedSlice(a: []align(1) const u32, b: []align(1) const u32) u32 {
     return a[0] + b[0];