The QMacApperanceStyle<QMacStyle> template instantiation in QMacStyle::create() triggers a clang compiler crash

Error Details

Compiler Crash

clang++: /home/mccakit/llvm-project/clang/lib/Sema/TreeTransform.h:17056: 
clang::ExprResult clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformBlockExpr(clang::BlockExpr *) 
[Derived = (anonymous namespace)::TemplateInstantiator]: 
Assertion `(!blockScope->isCXXThisCaptured() || oldBlock->capturesCXXThis()) && 
"this pointer isn't captured in the old block"' failed.

Problematic Code

Template Definition

template<typename Style>
class QMacApperanceStyle : public Style
{
public:
    void drawPrimitive(typename Style::PrimitiveElement pe, const QStyleOption *opt, QPainter *p
                       OPTIONAL_WIDGET_ARGUMENT) const override
    {
        [NSApp.effectiveAppearance performAsCurrentDrawingAppearance:^

{             Style::drawPrimitive(pe, opt, p                 FORWARD_OPTIONAL_WIDGET_ARGUMENT);         }

];
    }
    // ... similar methods for drawControl and drawComplexControl
};

Instantiation Site

QMacStyle *QMacStyle::create()

{     return new QMacApperanceStyle<QMacStyle>; // <- Causes compiler crash }

Proposed Solutions

Option 1: Fix Template Capture

Modify the template to explicitly handle this capture:

void drawPrimitive(typename Style::PrimitiveElement pe, const QStyleOption *opt, QPainter *p
                   OPTIONAL_WIDGET_ARGUMENT) const override
{
    const auto* self = this;
    [NSApp.effectiveAppearance performAsCurrentDrawingAppearance:^

{         self->Style::drawPrimitive(pe, opt, p             FORWARD_OPTIONAL_WIDGET_ARGUMENT);     }

];
}