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[clang] Add FixItHint for designated init order (#173136)
Generate fix-it for C++20 designated initializers when the initializers do not match the declaration order in the structure.
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‎clang/docs/ReleaseNotes.rst‎

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@@ -493,6 +493,9 @@ Improvements to Clang's diagnostics
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carries messages like 'In file included from ...' or 'In module ...'.
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Now the include/import locations are written into `sarif.run.result.relatedLocations`.
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- Clang now generates a fix-it for C++20 designated initializers when the
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initializers do not match the declaration order in the structure.
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Improvements to Clang's time-trace
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----------------------------------
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‎clang/lib/Sema/SemaInit.cpp‎

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@@ -31,8 +31,10 @@
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#include "clang/Sema/SemaHLSL.h"
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#include "clang/Sema/SemaObjC.h"
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#include "llvm/ADT/APInt.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/FoldingSet.h"
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#include "llvm/ADT/PointerIntPair.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Support/ErrorHandling.h"
@@ -3092,6 +3094,65 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
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PrevField = *FI;
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}
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const auto GenerateDesignatedInitReorderingFixit =
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[&](SemaBase::SemaDiagnosticBuilder &Diag) {
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struct ReorderInfo {
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int Pos{};
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const Expr *InitExpr{};
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};
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llvm::SmallDenseMap<IdentifierInfo *, int> MemberNameInx{};
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llvm::SmallVector<ReorderInfo, 16> ReorderedInitExprs{};
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const auto *CxxRecord =
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IList->getSemanticForm()->getType()->getAsCXXRecordDecl();
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for (const FieldDecl *Field : CxxRecord->fields())
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MemberNameInx[Field->getIdentifier()] = Field->getFieldIndex();
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for (const Expr *Init : IList->inits()) {
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if (const auto *DI =
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dyn_cast_if_present<DesignatedInitExpr>(Init)) {
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// We expect only one Designator
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if (DI->size() != 1)
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return;
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const IdentifierInfo *const FieldName =
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DI->getDesignator(0)->getFieldName();
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// In case we have an unknown initializer in the source, not in
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// the record
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if (MemberNameInx.contains(FieldName))
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ReorderedInitExprs.emplace_back(
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ReorderInfo{MemberNameInx.at(FieldName), Init});
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}
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}
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llvm::sort(ReorderedInitExprs,
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[](const ReorderInfo &A, const ReorderInfo &B) {
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return A.Pos < B.Pos;
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});
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llvm::SmallString<128> FixedInitList{};
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SourceManager &SM = SemaRef.getSourceManager();
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const LangOptions &LangOpts = SemaRef.getLangOpts();
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// In a derived Record, first n base-classes are initialized first.
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// They do not use designated init, so skip them
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const ArrayRef<clang::Expr *> IListInits =
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IList->inits().drop_front(CxxRecord->getNumBases());
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// loop over each existing expressions and apply replacement
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for (const auto &[OrigExpr, Repl] :
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llvm::zip(IListInits, ReorderedInitExprs)) {
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CharSourceRange CharRange = CharSourceRange::getTokenRange(
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Repl.InitExpr->getSourceRange());
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const StringRef InitText =
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Lexer::getSourceText(CharRange, SM, LangOpts);
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Diag << FixItHint::CreateReplacement(OrigExpr->getSourceRange(),
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InitText.str());
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}
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};
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if (PrevField &&
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PrevField->getFieldIndex() > KnownField->getFieldIndex()) {
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SemaRef.Diag(DIE->getInit()->getBeginLoc(),
@@ -3101,9 +3162,10 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
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unsigned OldIndex = StructuredIndex - 1;
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if (StructuredList && OldIndex <= StructuredList->getNumInits()) {
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if (Expr *PrevInit = StructuredList->getInit(OldIndex)) {
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SemaRef.Diag(PrevInit->getBeginLoc(),
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diag::note_previous_field_init)
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<< PrevField << PrevInit->getSourceRange();
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auto Diag = SemaRef.Diag(PrevInit->getBeginLoc(),
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diag::note_previous_field_init)
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<< PrevField << PrevInit->getSourceRange();
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GenerateDesignatedInitReorderingFixit(Diag);
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}
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}
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}

‎clang/test/SemaCXX/cxx20-designated-initializer-fixits.cpp‎

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// RUN: %clang_cc1 -std=c++20 %s -Wreorder-init-list -fdiagnostics-parseable-fixits 2>&1 | FileCheck %s
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// These tests are from clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
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struct C { int :0, x, :0, y, :0; };
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C c = {
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.x = 1,
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.x = 1,
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.y = 1,
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.y = 1,
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.x = 1,
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.x = 1,
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};
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:3-[[@LINE-7]]:9}:".x = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:3-[[@LINE-7]]:9}:".x = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:3-[[@LINE-7]]:9}:".x = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:3-[[@LINE-7]]:9}:".x = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:3-[[@LINE-7]]:9}:".y = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:3-[[@LINE-7]]:9}:".y = 1"
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namespace GH63605 {
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struct A {
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unsigned x;
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unsigned y;
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unsigned z;
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};
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struct B {
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unsigned a;
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unsigned b;
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};
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struct : public A, public B {
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unsigned : 2;
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unsigned a : 6;
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unsigned : 1;
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unsigned b : 6;
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unsigned : 2;
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unsigned c : 6;
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unsigned d : 1;
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unsigned e : 2;
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} data = {
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{.z=0,
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.y=1,
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.x=2},
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{.b=3,
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.a=4},
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.e = 1,
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.d = 1,
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.c = 1,
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.b = 1,
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.a = 1,
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};
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}
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// CHECK: fix-it:"{{.*}}":{[[@LINE-17]]:4-[[@LINE-17]]:8}:".x=2"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-15]]:4-[[@LINE-15]]:8}:".y=1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-14]]:4-[[@LINE-14]]:8}:".z=0"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-14]]:4-[[@LINE-14]]:8}:".a=4"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-14]]:4-[[@LINE-14]]:8}:".b=3"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-14]]:5-[[@LINE-14]]:11}:".a = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-13]]:5-[[@LINE-13]]:11}:".b = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-12]]:5-[[@LINE-12]]:11}:".c = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-12]]:5-[[@LINE-12]]:11}:".d = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-12]]:5-[[@LINE-12]]:11}:".e = 1"
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// END tests from clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp
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namespace reorder_derived {
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struct col {
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int r;
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int g;
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int b;
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};
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struct point {
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float x;
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float y;
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float z;
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};
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struct derived : public col, public point {
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int z2;
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int z1;
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};
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void test() {
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derived a {
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{.b = 1, .g = 2, .r = 3},
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{ .z = 1, .y=2, .x = 3 },
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.z1 = 1,
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.z2 = 2,
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};
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}
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// CHECK: fix-it:"{{.*}}":{[[@LINE-6]]:6-[[@LINE-6]]:12}:".r = 3"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-7]]:14-[[@LINE-7]]:20}:".g = 2"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-8]]:22-[[@LINE-8]]:28}:".b = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-8]]:15-[[@LINE-8]]:19}:".y=2"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-9]]:21-[[@LINE-9]]:28}:".z = 1"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-10]]:7-[[@LINE-10]]:13}:".x = 3"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-10]]:5-[[@LINE-10]]:12}:".z2 = 2"
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// CHECK: fix-it:"{{.*}}":{[[@LINE-10]]:5-[[@LINE-10]]:12}:".z1 = 1"
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} // namespace reorder_derived

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