Commit 9aa65c0e8e6e4135dcc04bcb388d1fa38c6d10f6 | zig

author	Ben Noordhuis <info@bnoordhuis.nl> 2018-02-26 18:40:33+01:00
committer	Ben Noordhuis <info@bnoordhuis.nl> 2018-02-26 19:56:26+01:00
log	9aa65c0e8e6e4135dcc04bcb388d1fa38c6d10f6
tree	d7bedb06367d28f4851fc2020f3fa6ca84b96294
parent	1eecfdaa9b9c04e50058695b8df9978ef47f121a

allow implicit cast from &const to ?&const &const

Allow implicit casts from n-th degree const pointers to nullable const
pointers of degree n+1.  That is:

    fn f() void {
        const s = S {};
        const p = &s;
        g(p);   // Works.
        g(&p);  // So does this.
    }

    fn g(_: ?&const &const S) void {  // Nullable 2nd degree const ptr.
    }

Fixes #731 some more.

2 files changed, 33 insertions(+), 1 deletions(-)

src
- ir.cpp
test
- cases
  - cast.zig

src/ir.cpp+2-1

...	@@ -8830,7 +8830,8 @@ static IrInstruction ir_analyze_cast(IrAnalyze ira, IrInstruction *source_inst	...	@@ -8830,7 +8830,8 @@ static IrInstruction ir_analyze_cast(IrAnalyze ira, IrInstruction *source_inst
8830	}	8830	}
8831	} else if (wanted_child_type->id == TypeTableEntryIdPointer &&	8831	} else if (wanted_child_type->id == TypeTableEntryIdPointer &&
8832	wanted_child_type->data.pointer.is_const &&	8832	wanted_child_type->data.pointer.is_const &&
8833	is_container(actual_type)) {	8833	(actual_type->id == TypeTableEntryIdPointer \|\| is_container(actual_type)))
		8834	{
8834	IrInstruction *cast1 = ir_analyze_cast(ira, source_instr, wanted_child_type, value);	8835	IrInstruction *cast1 = ir_analyze_cast(ira, source_instr, wanted_child_type, value);
8835	if (type_is_invalid(cast1->value.type))	8836	if (type_is_invalid(cast1->value.type))
8836	return ira->codegen->invalid_instruction;	8837	return ira->codegen->invalid_instruction;

test/cases/cast.zig+31

...	@@ -103,6 +103,37 @@ const Enum = enum {	...	@@ -103,6 +103,37 @@ const Enum = enum {
103	}	103	}
104	};	104	};
105		105
		106	test "implicitly cast indirect pointer to maybe-indirect pointer" {
		107	const S = struct {
		108	const Self = this;
		109	x: u8,
		110	fn constConst(p: &const &const Self) u8 {
		111	return (*p).x;
		112	}
		113	fn maybeConstConst(p: ?&const &const Self) u8 {
		114	return (*??p).x;
		115	}
		116	fn constConstConst(p: &const &const &const Self) u8 {
		117	return (**p).x;
		118	}
		119	fn maybeConstConstConst(p: ?&const &const &const Self) u8 {
		120	return (**??p).x;
		121	}
		122	};
		123	const s = S { .x = 42 };
		124	const p = &s;
		125	const q = &p;
		126	const r = &q;
		127	assert(42 == S.constConst(p));
		128	assert(42 == S.constConst(q));
		129	assert(42 == S.maybeConstConst(p));
		130	assert(42 == S.maybeConstConst(q));
		131	assert(42 == S.constConstConst(q));
		132	assert(42 == S.constConstConst(r));
		133	assert(42 == S.maybeConstConstConst(q));
		134	assert(42 == S.maybeConstConstConst(r));
		135	}
		136
106	test "explicit cast from integer to error type" {	137	test "explicit cast from integer to error type" {
107	testCastIntToErr(error.ItBroke);	138	testCastIntToErr(error.ItBroke);
108	comptime testCastIntToErr(error.ItBroke);	139	comptime testCastIntToErr(error.ItBroke);