Commit 6d24c40b6e79176b05ec735adcecfd346b03f059 | zig

author	Veikka Tuominen <git@vexu.eu> 2022-06-30 16:10:15+03:00
committer	Veikka Tuominen <git@vexu.eu> 2022-07-01 09:29:13+03:00
log	6d24c40b6e79176b05ec735adcecfd346b03f059
tree	26c5240abbadf123a98c0077b4521e9c61a4c2fc
parent	902dc8c721c762bc5d1b9786bad47b21da45042c

Sema: improve bitcast to enum error

3 files changed, 28 insertions(+), 14 deletions(-)

src
- Sema.zig
test
- cases
  - compile_errors
    bitCast_to_enum_type.zig
    stage1
    obj
    bitCast_to_enum_type.zig

src/Sema.zig+16-4

 @@ -7617,11 +7617,11 @@ fn zirBitcast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
     const extra = sema.code.extraData(Zir.Inst.Bin, inst_data.payload_index).data;
     const dest_ty = try sema.resolveType(block, dest_ty_src, extra.lhs);
+    const operand = try sema.resolveInst(extra.rhs);
     switch (dest_ty.zigTypeTag()) {
         .AnyFrame,
         .ComptimeFloat,
         .ComptimeInt,
-        .Enum,
         .EnumLiteral,
         .ErrorSet,
         .ErrorUnion,
 @@ -7634,7 +7634,21 @@ fn zirBitcast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
         .Type,
         .Undefined,
         .Void,
-        => return sema.fail(block, dest_ty_src, "invalid type '{}' for @bitCast", .{dest_ty.fmt(sema.mod)}),
+        => return sema.fail(block, dest_ty_src, "cannot @bitCast to '{}'", .{dest_ty.fmt(sema.mod)}),
+        .Enum => {
+            const msg = msg: {
+                const msg = try sema.errMsg(block, dest_ty_src, "cannot @bitCast to '{}'", .{dest_ty.fmt(sema.mod)});
+                errdefer msg.destroy(sema.gpa);
+                switch (sema.typeOf(operand).zigTypeTag()) {
+                    .Int, .ComptimeInt => try sema.errNote(block, dest_ty_src, msg, "use @intToEnum for type coercion", .{}),
+                    else => {},
+                }
+                break :msg msg;
+            };
+            return sema.failWithOwnedErrorMsg(block, msg);
+        },
         .Pointer => return sema.fail(block, dest_ty_src, "cannot @bitCast to '{}', use @ptrCast to cast to a pointer", .{
             dest_ty.fmt(sema.mod),
 @@ -7658,8 +7672,6 @@ fn zirBitcast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
         .Vector,
         => {},
     }
-    const operand = try sema.resolveInst(extra.rhs);
     return sema.bitCast(block, dest_ty, operand, operand_src);
 }

test/cases/compile_errors/bitCast_to_enum_type.zig created+12

...	@@ -0,0 +1,12 @@
1	export fn entry() void {
2	const E = enum(u32) { a, b };
3	const y = @bitCast(E, @as(u32, 3));
4	_ = y;
5	}
6
7	// error
8	// backend=stage2
9	// target=native
10	//
11	// :3:24: error: cannot @bitCast to 'tmp.entry.E'
12	// :3:24: note: use @intToEnum for type coercion

test/cases/compile_errors/stage1/obj/bitCast_to_enum_type.zig deleted-10

...	@@ -1,10 +0,0 @@
1	export fn entry() void {
2	const y = @bitCast(enum(u32) { a, b }, @as(u32, 3));
3	_ = y;
4	}
5
6	// error
7	// backend=stage1
8	// target=native
9	//
10	// tmp.zig:2:24: error: cannot cast a value of type 'y'