harec

commit 46f819db532a864b1934a81c66a75376eaacdb41
parent e3dbd78a2a5dc4f1d004a2462efa8e98c622b596
Author: Drew DeVault <sir@cmpwn.com>
Date:   Sun,  3 Jan 2021 12:30:19 -0500

Prevent assignment of *const <type> to *void

Diffstat:
M
include/types.h
 | 
1
+
M
rt/+linux/syscalls.ha
 | 
2
+-
M
rt/abort.ha
 | 
4
----
M
src/type_store.c
 | 
8
+++++---
M
src/types.c
 | 
6
++++++

5 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/include/types.h b/include/types.h
@@ -151,6 +151,7 @@ extern const struct type
 	builtin_type_const_uintptr,
 	builtin_type_const_rune,
 	builtin_type_const_size,
+	builtin_type_const_void,
 	// etc
 	builtin_type_const_ptr_char,
 	builtin_type_str,
diff --git a/rt/+linux/syscalls.ha b/rt/+linux/syscalls.ha
@@ -6,7 +6,7 @@ fn syscall4(u64, u64, u64, u64, u64) u64;
 fn syscall5(u64, u64, u64, u64, u64, u64) u64;
 fn syscall6(u64, u64, u64, u64, u64, u64, u64) u64;
 
-export fn write(fd: int, buf: *void, count: size) size =
+export fn write(fd: int, buf: *const void, count: size) size =
 	syscall3(SYS_write, fd: u64, buf: uintptr: u64, count: u64): size;
 
 export fn close(fd: int) int = syscall1(SYS_close, fd: u64): int;
diff --git a/rt/abort.ha b/rt/abort.ha
@@ -1,8 +1,4 @@
 export @noreturn @symbol("rt.abort") fn _abort(msg: str) void = {
-	// XXX: these implicit casts call const to fall off because const types
-	// are assignable from non-const types. This should not transit pointer
-	// secondaries. Write should be updated to *const void, but not before
-	// the compiler catches the error.
 	const prefix = "Abort: ";
 	write(2, prefix: *const char, len(prefix));
 	write(2, msg: *const char, len(msg));
diff --git a/src/type_store.c b/src/type_store.c
@@ -77,8 +77,10 @@ type_is_assignable(struct type_store *store,
 		case TYPE_STORAGE_NULL:
 			return to->pointer.flags & PTR_NULLABLE;
 		case TYPE_STORAGE_POINTER:
-			if (to->pointer.referent->storage != TYPE_STORAGE_VOID &&
-					to->pointer.referent != from->pointer.referent) {
+			if (to->pointer.referent->storage == TYPE_STORAGE_VOID) {
+				// TODO: const transitivity
+				return to->pointer.referent->flags == from->pointer.referent->flags;
+			} else if (to->pointer.referent != from->pointer.referent) {
 				return false;
 			}
 			if (from->pointer.flags & PTR_NULLABLE) {
@@ -223,7 +225,7 @@ builtin_type_for_storage(enum type_storage storage, bool is_const)
 	case TYPE_STORAGE_UINTPTR:
 		return is_const ? &builtin_type_const_uintptr : &builtin_type_uintptr;
 	case TYPE_STORAGE_VOID:
-		return &builtin_type_void; // const void and void are the same type
+		return is_const ? &builtin_type_const_void : &builtin_type_void;
 	case TYPE_STORAGE_NULL:
 		return &builtin_type_null; // const null and null are the same type
 	case TYPE_STORAGE_STRING:
diff --git a/src/types.c b/src/types.c
@@ -398,6 +398,12 @@ builtin_type_const_size = {
 	.flags = TYPE_CONST,
 	.size = 8, // XXX: ARCH
 	.align = 8,
+},
+builtin_type_const_void = {
+	.storage = TYPE_STORAGE_VOID,
+	.flags = TYPE_CONST,
+	.size = 0,
+	.align = 0,
 };
 
 // Others