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Clarify reason implicit cast does not work for large RHS (#1168)

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* Clarify reason implicit cast does not work for large RHS
This commit is contained in:
isaachier 2018-06-29 14:52:25 -04:00 committed by Andrew Kelley
parent 0874a5ba77
commit f1c56f7f22
2 changed files with 32 additions and 0 deletions
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20
src/ir.cpp
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@ -11432,6 +11432,26 @@ static TypeTableEntry *ir_analyze_bit_shift(IrAnalyze *ira, IrInstructionBinOp *
} else {
TypeTableEntry *shift_amt_type = get_smallest_unsigned_int_type(ira->codegen,
op1->value.type->data.integral.bit_count - 1);
if (bin_op_instruction->op_id == IrBinOpBitShiftLeftLossy &&
op2->value.type->id == TypeTableEntryIdComptimeInt) {
if (!bigint_fits_in_bits(&op2->value.data.x_bigint,
shift_amt_type->data.integral.bit_count,
op2->value.data.x_bigint.is_negative)) {
Buf *val_buf = buf_alloc();
bigint_append_buf(val_buf, &op2->value.data.x_bigint, 10);
ErrorMsg* msg = ir_add_error(ira,
&bin_op_instruction->base,
buf_sprintf("RHS of shift is too large for LHS type"));
add_error_note(
ira->codegen,
msg,
op2->source_node,
buf_sprintf("value %s cannot fit into type %s",
buf_ptr(val_buf),
buf_ptr(&shift_amt_type->name)));
return ira->codegen->builtin_types.entry_invalid;
}
}
casted_op2 = ir_implicit_cast(ira, op2, shift_amt_type);
if (casted_op2 == ira->codegen->invalid_instruction)

12
test/compile_errors.zig
View File

@ -1677,6 +1677,18 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
".tmp_source.zig:1:16: error: integer value 300 cannot be implicitly casted to type 'u8'",
);
cases.add(
"invalid shift amount error",
\\const x : u8 = 2;
\\fn f() u16 {
\\ return x << 8;
\\}
\\export fn entry() u16 { return f(); }
,
".tmp_source.zig:3:14: error: RHS of shift is too large for LHS type",
".tmp_source.zig:3:17: note: value 8 cannot fit into type u3",
);
cases.add(
"incompatible number literals",
\\const x = 2 == 2.0;