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Fix new/free mismatch when differentiating delegating constructors. #1934

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Merged
vgvassilev merged 1 commit into from
Jul 30, 2026
Merged

Fix new/free mismatch when differentiating delegating constructors. #1934

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11 changes: 6 additions & 5 deletions lib/Differentiator/ReverseModeVisitor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -734,11 +734,12 @@ Expr* ReverseModeVisitor::getStdInitListSizeExpr(const Expr* E) {
initDiff.getExpr(), baseTSI,
{placementArg});
} else if (CI->isDelegatingInitializer()) {
auto* thisDRE = cast<DeclRefExpr>(thisExpr);
auto* thisVD = cast<VarDecl>(thisDRE->getDecl());
Expr* newInit = utils::BuildCXXNewExpr(m_Sema, baseTy, nullptr,
initDiff.getExpr(), baseTSI);
SetDeclInit(thisVD, newInit);
// Placement-new into the malloc'd `_this` (paired with free(_this)),
// as the base-initializer path above does. An allocating
// `new ClassTy(args)` here would be freed with free() -- a mismatch.
initCall =
utils::BuildCXXNewExpr(m_Sema, baseTy, /*arraySize=*/nullptr,
initDiff.getExpr(), baseTSI, {thisExpr});
}
}
CompoundStmt* block = endBlock(direction::reverse);
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8 changes: 4 additions & 4 deletions test/Gradient/Constructors.C
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Expand Up @@ -2,8 +2,6 @@
// RUN: ./Constructors.out | %filecheck_exec %s
// RUN: %cladclang -Xclang -plugin-arg-clad -Xclang -disable-tbr -Xclang -plugin-arg-clad -Xclang -enable-va %s -I%S/../../include -oConstructors.out
// RUN: ./Constructors.out | %filecheck_exec %s
// FIXME: real new/free mismatch for delegating constructors; drop when fixed.
// XFAIL: valgrind

#include "clad/Differentiator/Differentiator.h"
#include "clad/Differentiator/STLBuiltins.h"
Expand Down Expand Up @@ -368,15 +366,17 @@ double fn6(double x, double y) {
} // x^2 * y

// CHECK: static clad::ValueAndAdjoint<argByValWrapper, argByValWrapper> constructor_reverse_forw(clad::Tag<argByValWrapper>, double v, double u, double _d_v, double _d_u) {
// CHECK-NEXT: argByValWrapper *_this = new argByValWrapper(v);
// CHECK-NEXT: argByValWrapper *_this = (argByValWrapper *)malloc(sizeof(argByValWrapper));
// CHECK-NEXT: argByValWrapper *_d_this = (argByValWrapper *)malloc(sizeof(argByValWrapper));
// CHECK-NEXT: memset(_d_this, 0, sizeof(argByValWrapper));
// CHECK-NEXT: new (_this) argByValWrapper(v);
// CHECK-NEXT: _this->z = _this->y * u;
// CHECK-NEXT: return {*_this, *_d_this};
// CHECK-NEXT: }

// CHECK: static void constructor_pullback(double v, double u, argByValWrapper *_d_this, double *_d_v, double *_d_u) {
// CHECK-NEXT: argByValWrapper *_this = new argByValWrapper(v);
// CHECK-NEXT: argByValWrapper *_this = (argByValWrapper *)malloc(sizeof(argByValWrapper));
// CHECK-NEXT: new (_this) argByValWrapper(v);
// CHECK-NEXT: _this->z = _this->y * u;
// CHECK-NEXT: {
// CHECK-NEXT: double _r_d0 = _d_this->z;
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