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

test/cases/cast.zig+31

...	...	@@ -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	137	test "explicit cast from integer to error type" {
107	138	testCastIntToErr(error.ItBroke);
108	139	comptime testCastIntToErr(error.ItBroke);