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Fixed lambdas constexpr display and added support for P2564r3. #746

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Merged
andreasfertig merged 1 commit into from
Aug 2, 2026
Merged

Fixed lambdas constexpr display and added support for P2564r3. #746

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52 changes: 25 additions & 27 deletions CodeGenerator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4704,10 +4704,8 @@ void CodeGenerator::InsertFunctionNameWithReturnType(const FunctionDecl& d
const bool requiresComment{isCXXMethodDecl and not methodDecl->isUserProvided() and
not methodDecl->isExplicitlyDefaulted()};
// [expr.prim.lambda.closure] p7 consteval/constexpr are obtained from the call operator
const bool isLambdaStaticInvoker{isCXXMethodDecl and methodDecl->isLambdaStaticInvoker()};
const FunctionDecl& constExprDecl{not isLambdaStaticInvoker ? decl
: *methodDecl->getParent()->getLambdaCallOperator()};
const auto desugaredReturnType = GetType(GetDesugarReturnType(decl));
const bool isLambdaStaticInvoker{isCXXMethodDecl and methodDecl->isLambdaStaticInvoker()};
const auto desugaredReturnType = GetType(GetDesugarReturnType(decl));

if(methodDecl) {
if(requiresComment) {
Expand Down Expand Up @@ -4793,34 +4791,34 @@ void CodeGenerator::InsertFunctionNameWithReturnType(const FunctionDecl& d
}
}

if(constExprDecl.isConstexpr()) {
const bool skipConstexpr{isLambda and not isa<CXXConversionDecl>(constExprDecl)};
// Special treatment for a conversion operator in a captureless lambda. It appears that if the call operator
// is consteval the conversion operator must be as well, otherwise it cannot take the address of the invoke
// function.
const bool isConversionOpWithConstevalCallOp{[&]() {
if(methodDecl) {
if(const auto callOp = methodDecl->getParent()->getLambdaCallOperator()) {
return callOp->isConsteval();
}
}
if(const FunctionDecl& constExprDecl{isLambdaStaticInvoker ? *methodDecl->getParent()->getLambdaCallOperator()
: decl};
constExprDecl.isConstexpr()) {

return false;
}()};
ConstexprSpecKind constexrKind{constExprDecl.isImmediateFunction() ? ConstexprSpecKind::Consteval
: constExprDecl.getConstexprKind()};

if(not isConversionOpWithConstevalCallOp and constExprDecl.isConstexprSpecified()) {
if(skipConstexpr) {
mOutputFormatHelper.Append(kwCommentStart);
}

mOutputFormatHelper.Append(kwConstExprSpace);
if(isLambda) {
// Special treatment for a conversion operator in a captureless lambda. It appears that if the call operator
// is consteval the conversion operator must be manually promoted to consteval as well, otherwise it cannot
// take the address of the invoke function.
if(const auto* callOp{methodDecl->getParent()->getLambdaCallOperator()}; isa<CXXConversionDecl>(decl)) {
if(callOp->isConsteval()) {
constexrKind = ConstexprSpecKind::Consteval;
}

if(skipConstexpr) {
mOutputFormatHelper.Append(kwCCommentEndSpace);
} else if(llvm::SmallVector<clang::PartialDiagnosticAt, 8> Diags{};
// remove a potential constexpr from a lambda if the function is unusable in a constant expression
not clang::Expr::isPotentialConstantExpr(callOp, Diags)) {
constexrKind = ConstexprSpecKind::Unspecified;
}
}

} else if(isConversionOpWithConstevalCallOp or constExprDecl.isConsteval()) {
mOutputFormatHelper.Append(kwConstEvalSpace);
switch(constexrKind) {
case ConstexprSpecKind::Unspecified: break;
case ConstexprSpecKind::Constexpr: mOutputFormatHelper.Append(kwConstExprSpace); break;
case ConstexprSpecKind::Consteval: mOutputFormatHelper.Append(kwConstEvalSpace); break;
case ConstexprSpecKind::Constinit: break;
}
}

Expand Down
4 changes: 2 additions & 2 deletions tests/Basic.Start.Main.P5.3Test.expect
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ int main()
class __lambda_3_13
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return 2;
}
Expand All @@ -16,7 +16,7 @@ int main()
};

private:
static inline /*constexpr */ int __invoke()
static inline constexpr int __invoke()
{
return __lambda_3_13{}.operator()();
}
Expand Down
4 changes: 2 additions & 2 deletions tests/Basic.Start.Main.P5.4Test.expect
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Expand Up @@ -8,7 +8,7 @@ int main(int argc, const char ** argv)
class __lambda_5_13
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return 2;
}
Expand All @@ -20,7 +20,7 @@ int main(int argc, const char ** argv)
};

private:
static inline /*constexpr */ int __invoke()
static inline constexpr int __invoke()
{
return __lambda_5_13{}.operator()();
}
Expand Down
6 changes: 3 additions & 3 deletions tests/ConstraintAutoParameterTest.expect
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Original file line number Diff line number Diff line change
Expand Up @@ -7,20 +7,20 @@ class __lambda_6_15
{
public:
template<C type_parameter_0_0>
inline /*constexpr */ auto operator()(type_parameter_0_0 container) const
inline constexpr auto operator()(type_parameter_0_0 container) const
{
}

#ifdef INSIGHTS_USE_TEMPLATE
template<>
inline /*constexpr */ void operator()<int>(int container) const
inline constexpr void operator()<int>(int container) const
{
}
#endif

private:
template<C type_parameter_0_0>
static inline /*constexpr */ auto __invoke(type_parameter_0_0 container)
static inline constexpr auto __invoke(type_parameter_0_0 container)
{
return __lambda_6_15{}.operator()<type_parameter_0_0>(container);
}
Expand Down
4 changes: 2 additions & 2 deletions tests/EmptyLambda.expect
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ void foo()
class __lambda_2_1
{
public:
inline /*constexpr */ void operator()() const
inline constexpr void operator()() const
{
}

Expand All @@ -15,7 +15,7 @@ void foo()
};

private:
static inline /*constexpr */ void __invoke()
static inline constexpr void __invoke()
{
__lambda_2_1{}.operator()();
}
Expand Down
30 changes: 15 additions & 15 deletions tests/ForStmtWithLambdaInInitTest.expect
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Expand Up @@ -7,7 +7,7 @@ int main()
class __lambda_7_17
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return x * 2;
}
Expand All @@ -24,7 +24,7 @@ int main()
class __lambda_11_17
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return x * 2;
}
Expand All @@ -37,7 +37,7 @@ int main()
class __lambda_11_43
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return x * 2;
}
Expand All @@ -54,7 +54,7 @@ int main()
class __lambda_15_9
{
public:
inline /*constexpr */ void operator()() const
inline void operator()() const
{
printf("started\n");
}
Expand All @@ -66,7 +66,7 @@ int main()
};

private:
static inline /*constexpr */ void __invoke()
static inline void __invoke()
{
__lambda_15_9{}.operator()();
}
Expand All @@ -77,7 +77,7 @@ int main()
class __lambda_15_37
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return --x;
}
Expand All @@ -90,7 +90,7 @@ int main()
class __lambda_15_59
{
public:
inline /*constexpr */ void operator()() const
inline void operator()() const
{
printf("after\n");
}
Expand All @@ -102,7 +102,7 @@ int main()
};

private:
static inline /*constexpr */ void __invoke()
static inline void __invoke()
{
__lambda_15_59{}.operator()();
}
Expand All @@ -116,7 +116,7 @@ int main()
class __lambda_19_9
{
public:
inline /*constexpr */ void operator()() const
inline void operator()() const
{
printf("started\n");
}
Expand All @@ -128,7 +128,7 @@ int main()
};

private:
static inline /*constexpr */ void __invoke()
static inline void __invoke()
{
__lambda_19_9{}.operator()();
}
Expand All @@ -139,7 +139,7 @@ int main()
class __lambda_20_9
{
public:
inline /*constexpr */ void operator()() const
inline void operator()() const
{
printf("started\n");
}
Expand All @@ -151,7 +151,7 @@ int main()
};

private:
static inline /*constexpr */ void __invoke()
static inline void __invoke()
{
__lambda_20_9{}.operator()();
}
Expand All @@ -162,7 +162,7 @@ int main()
class __lambda_20_37
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return --x;
}
Expand All @@ -175,7 +175,7 @@ int main()
class __lambda_20_59
{
public:
inline /*constexpr */ void operator()() const
inline void operator()() const
{
printf("after\n");
}
Expand All @@ -187,7 +187,7 @@ int main()
};

private:
static inline /*constexpr */ void __invoke()
static inline void __invoke()
{
__lambda_20_59{}.operator()();
}
Expand Down
12 changes: 6 additions & 6 deletions tests/IfStmtWithLambdaInInitTest.expect
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ int main()
class __lambda_3_14
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return 2;
}
Expand All @@ -17,7 +17,7 @@ int main()
};

private:
static inline /*constexpr */ int __invoke()
static inline constexpr int __invoke()
{
return __lambda_3_14{}.operator()();
}
Expand All @@ -29,7 +29,7 @@ int main()
class __lambda_3_34
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return 3;
}
Expand All @@ -41,7 +41,7 @@ int main()
};

private:
static inline /*constexpr */ int __invoke()
static inline constexpr int __invoke()
{
return __lambda_3_34{}.operator()();
}
Expand All @@ -53,7 +53,7 @@ int main()
class __lambda_3_53
{
public:
inline /*constexpr */ int operator()() const
inline constexpr int operator()() const
{
return 4;
}
Expand All @@ -65,7 +65,7 @@ int main()
};

private:
static inline /*constexpr */ int __invoke()
static inline constexpr int __invoke()
{
return __lambda_3_53{}.operator()();
}
Expand Down
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