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

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Merged
merged 4 commits into from
Jun 29, 2018
Merged

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

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b62f803
Clarify reason implicit cast does not work for large RHS
isaachier Jun 28, 2018
b7f2238
Add test case
Jun 28, 2018
7f6e5fb
Check for bad shift upfront to avoid multiple errors later
Jun 28, 2018
9991287
Add more info in additional error note
isaachier Jun 29, 2018
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20 changes: 20 additions & 0 deletions src/ir.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
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12 changes: 12 additions & 0 deletions test/compile_errors.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
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