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IRGen: Fix handling of empty fields in Clang-imported types. #15351

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Merged
merged 1 commit into from
Mar 20, 2018
Merged

IRGen: Fix handling of empty fields in Clang-imported types. #15351

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21 changes: 15 additions & 6 deletions lib/IRGen/GenStruct.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,8 @@ namespace {
llvm::Constant *getConstantFieldOffset(IRGenModule &IGM,
VarDecl *field) const {
auto &fieldInfo = getFieldInfo(field);
if (fieldInfo.getKind() == ElementLayout::Kind::Fixed) {
if (fieldInfo.getKind() == ElementLayout::Kind::Fixed
|| fieldInfo.getKind() == ElementLayout::Kind::Empty) {
return llvm::ConstantInt::get(IGM.SizeTy,
fieldInfo.getFixedByteOffset().getValue());
}
Expand Down Expand Up @@ -773,14 +774,22 @@ class ClangRecordLowering {
unsigned explosionEnd = NextExplosionIndex;

ElementLayout layout = ElementLayout::getIncomplete(fieldType);
layout.completeFixed(fieldType.isPOD(ResilienceExpansion::Maximal),
NextOffset, LLVMFields.size());
auto isEmpty = fieldType.isKnownEmpty(ResilienceExpansion::Maximal);
if (isEmpty)
layout.completeEmpty(fieldType.isPOD(ResilienceExpansion::Maximal),
NextOffset);
else
layout.completeFixed(fieldType.isPOD(ResilienceExpansion::Maximal),
NextOffset, LLVMFields.size());

FieldInfos.push_back(
ClangFieldInfo(swiftField, layout, explosionBegin, explosionEnd));
LLVMFields.push_back(fieldType.getStorageType());
NextOffset += fieldType.getFixedSize();
SpareBits.append(fieldType.getSpareBits());

if (!isEmpty) {
LLVMFields.push_back(fieldType.getStorageType());
NextOffset += fieldType.getFixedSize();
SpareBits.append(fieldType.getSpareBits());
}
}

/// Add padding to get up to the given offset.
Expand Down
4 changes: 4 additions & 0 deletions test/IRGen/Inputs/clang_empty_type.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
struct TrailingArray {
int size;
char buffer[0];
};
6 changes: 6 additions & 0 deletions test/IRGen/clang_empty_type.swift
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@@ -0,0 +1,6 @@
// RUN: %target-swift-frontend -emit-ir -verify -import-objc-header %S/Inputs/clang_empty_type.h %s

public func projectTrailingArray(x: inout TrailingArray) {
x.size = 2
x.buffer = ()
}