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https://github.com/carbon-language/carbon-lang.git
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Richard Smith
76576c1387
In general, LLVM's parsing of decimal integers to `APInt`s forms an `APInt` that is 4n bits wide, where n is the length of the integer, and the `isNegative` check only checks the high bit. In this case, we form an `APInt` that is four bits wide, with the high bit set, which we reject because we think it's "negative". These two array lengths are the only ones where this happens -- if the decimal integer value is two characters long, we form an `APInt` that is eight bits wide but holds a value < 100, so the high bit is never set, and the same applies for longer integers too. An `IntegerLiteral` is never negative, so we don't need the `isNegative` check, and in fact it only detects the n=8 and n=9 cases.
57 lines
2.1 KiB
C++
57 lines
2.1 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/check/context.h"
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#include "toolchain/parse/node_kind.h"
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#include "toolchain/sem_ir/node.h"
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#include "toolchain/sem_ir/node_kind.h"
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namespace Carbon::Check {
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auto HandleArrayExpressionStart(Context& /*context*/,
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Parse::Node /*parse_node*/) -> bool {
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return true;
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}
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auto HandleArrayExpressionSemi(Context& context, Parse::Node parse_node)
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-> bool {
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context.node_stack().Push(parse_node);
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return true;
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}
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auto HandleArrayExpression(Context& context, Parse::Node parse_node) -> bool {
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// TODO: Handle array type with undefined bound.
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if (context.parse_tree().node_kind(context.node_stack().PeekParseNode()) ==
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Parse::NodeKind::ArrayExpressionSemi) {
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context.node_stack().PopAndIgnore();
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context.node_stack().PopAndIgnore();
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return context.TODO(parse_node, "HandleArrayExpressionWithoutBounds");
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}
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auto bound_node_id = context.node_stack().PopExpression();
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context.node_stack()
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.PopAndDiscardSoloParseNode<Parse::NodeKind::ArrayExpressionSemi>();
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auto element_type_node_id = context.node_stack().PopExpression();
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auto bound_node = context.semantics_ir().GetNode(bound_node_id);
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if (bound_node.kind() == SemIR::NodeKind::IntegerLiteral) {
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auto bound_value = context.semantics_ir().GetIntegerLiteral(
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bound_node.GetAsIntegerLiteral());
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// TODO: Produce an error if the array type is too large.
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if (bound_value.getBitWidth() <= 64) {
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context.AddNodeAndPush(
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parse_node,
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SemIR::Node::ArrayType::Make(
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parse_node, SemIR::TypeId::TypeType, bound_node_id,
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context.ExpressionAsType(parse_node, element_type_node_id)));
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return true;
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}
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}
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CARBON_DIAGNOSTIC(InvalidArrayExpression, Error, "Invalid array expression.");
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context.emitter().Emit(parse_node, InvalidArrayExpression);
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context.node_stack().Push(parse_node, SemIR::NodeId::BuiltinError);
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return true;
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}
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} // namespace Carbon::Check
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