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disallow '_' prong when switching on non-exhaustive tagged union

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A tagged union cannot legally be initiated to an invalid enumeration
This commit is contained in:
Vexu 2020-07-27 18:04:08 +03:00
parent 65185016f1
commit 1e835e0fcc
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GPG Key ID: 59AEB8936E16A6AC
3 changed files with 64 additions and 7 deletions
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16
src/ir.cpp
View File

@ -14138,7 +14138,7 @@ static IrInstGen *ir_analyze_union_to_tag(IrAnalyze *ira, IrInst* source_instr,
// If there is only 1 possible tag, then we know at comptime what it is.
if (wanted_type->data.enumeration.layout == ContainerLayoutAuto &&
wanted_type->data.enumeration.src_field_count == 1 &&
!wanted_type->data.enumeration.non_exhaustive) // TODO are non-exhaustive union tag types supposed to be allowed?
!wanted_type->data.enumeration.non_exhaustive)
{
IrInstGen *result = ir_const(ira, source_instr, wanted_type);
result->value->special = ConstValSpecialStatic;
@ -23816,7 +23816,6 @@ static IrInstGen *ir_analyze_instruction_switch_target(IrAnalyze *ira,
bigint_init_bigint(&result->value->data.x_enum_tag, &pointee_val->data.x_union.tag);
return result;
}
// TODO are non-exhaustive union tag types supposed to be allowed?
if (tag_type->data.enumeration.src_field_count == 1 && !tag_type->data.enumeration.non_exhaustive) {
IrInstGen *result = ir_const(ira, &switch_target_instruction->base.base, tag_type);
TypeEnumField *only_field = &tag_type->data.enumeration.fields[0];
@ -28839,6 +28838,10 @@ static IrInstGen *ir_analyze_instruction_check_switch_prongs(IrAnalyze *ira,
if (type_is_invalid(switch_type))
return ira->codegen->invalid_inst_gen;
ZigValue *original_value = ((IrInstSrcSwitchTarget *)(instruction->target_value))->target_value_ptr->child->value;
bool target_is_originally_union = original_value->type->id == ZigTypeIdPointer &&
original_value->type->data.pointer.child_type->id == ZigTypeIdUnion;
if (switch_type->id == ZigTypeIdEnum) {
HashMap<BigInt, AstNode *, bigint_hash, bigint_eql> field_prev_uses = {};
field_prev_uses.init(switch_type->data.enumeration.src_field_count);
@ -28894,9 +28897,12 @@ static IrInstGen *ir_analyze_instruction_check_switch_prongs(IrAnalyze *ira,
}
}
if (instruction->have_underscore_prong) {
if (!switch_type->data.enumeration.non_exhaustive){
if (!switch_type->data.enumeration.non_exhaustive) {
ir_add_error(ira, &instruction->base.base,
buf_sprintf("switch on non-exhaustive enum has `_` prong"));
buf_sprintf("switch on exhaustive enum has `_` prong"));
} else if (target_is_originally_union) {
ir_add_error(ira, &instruction->base.base,
buf_sprintf("`_` prong not allowed when switching on tagged union"));
}
for (uint32_t i = 0; i < switch_type->data.enumeration.src_field_count; i += 1) {
TypeEnumField *enum_field = &switch_type->data.enumeration.fields[i];
@ -28911,7 +28917,7 @@ static IrInstGen *ir_analyze_instruction_check_switch_prongs(IrAnalyze *ira,
}
}
} else if (instruction->else_prong == nullptr) {
if (switch_type->data.enumeration.non_exhaustive) {
if (switch_type->data.enumeration.non_exhaustive && !target_is_originally_union) {
ir_add_error(ira, &instruction->base.base,
buf_sprintf("switch on non-exhaustive enum must include `else` or `_` prong"));
}

32
test/compile_errors.zig
View File

@ -51,6 +51,23 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
"tmp.zig:17:23: error: cannot adjust alignment of zero sized type 'fn(u32) anytype'",
});
cases.addTest("switching with exhaustive enum has '_' prong ",
\\const E = enum{
\\ a,
\\ b,
\\};
\\pub export fn entry() void {
\\ var e: E = .b;
\\ switch (e) {
\\ .a => {},
\\ .b => {},
\\ _ => {},
\\ }
\\}
, &[_][]const u8{
"tmp.zig:7:5: error: switch on exhaustive enum has `_` prong",
});
cases.addTest("invalid pointer with @Type",
\\export fn entry() void {
\\ _ = @Type(.{ .Pointer = .{
@ -564,6 +581,10 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
\\ b,
\\ _,
\\};
\\const U = union(E) {
\\ a: i32,
\\ b: u32,
\\};
\\pub export fn entry() void {
\\ var e: E = .b;
\\ switch (e) { // error: switch not handling the tag `b`
@ -574,10 +595,17 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
\\ .a => {},
\\ .b => {},
\\ }
\\ var u = U{.a = 2};
\\ switch (u) { // error: `_` prong not allowed when switching on tagged union
\\ .a => {},
\\ .b => {},
\\ _ => {},
\\ }
\\}
, &[_][]const u8{
"tmp.zig:8:5: error: enumeration value 'E.b' not handled in switch",
"tmp.zig:12:5: error: switch on non-exhaustive enum must include `else` or `_` prong",
"tmp.zig:12:5: error: enumeration value 'E.b' not handled in switch",
"tmp.zig:16:5: error: switch on non-exhaustive enum must include `else` or `_` prong",
"tmp.zig:21:5: error: `_` prong not allowed when switching on tagged union",
});
cases.add("switch expression - unreachable else prong (bool)",

23
test/stage1/behavior/union.zig
View File

@ -690,3 +690,26 @@ test "method call on an empty union" {
S.doTheTest();
comptime S.doTheTest();
}
test "switching on non exhaustive union" {
const S = struct {
const E = enum(u8) {
a,
b,
_,
};
const U = union(E) {
a: i32,
b: u32,
};
fn doTheTest() void {
var a = U{ .a = 2 };
switch (a) {
.a => |val| expect(val == 2),
.b => unreachable,
}
}
};
S.doTheTest();
comptime S.doTheTest();
}