Rakete1111 updated this revision to Diff 128667.
Rakete1111 added a comment.
Rebased + friendly 2018 ping
https://reviews.llvm.org/D37442
Files:
include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Sema/Sema.h
lib/Parse/ParseDecl.cpp
lib/Parse/ParseDeclCXX.cpp
lib/Parse/ParseStmt.cpp
lib/Parse/ParseTemplate.cpp
lib/Sema/Sema.cpp
lib/Sema/SemaExpr.cpp
lib/Sema/SemaExprCXX.cpp
lib/Sema/TreeTransform.h
test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
Index: test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
===================================================================
--- test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
+++ test/CXX/expr/expr.prim/expr.prim.lambda/p2-template-parameter.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -std=c++17 %s -verify
+
+template<auto> struct Nothing {};
+
+void pr33696() {
+ Nothing<[]() { return 0; }()> nothing; // expected-error{{a lambda expression cannot appear in this context}}
+}
+
Index: lib/Sema/TreeTransform.h
===================================================================
--- lib/Sema/TreeTransform.h
+++ lib/Sema/TreeTransform.h
@@ -5507,7 +5507,7 @@
// decltype expressions are not potentially evaluated contexts
EnterExpressionEvaluationContext Unevaluated(
SemaRef, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
- /*IsDecltype=*/true);
+ Sema::ExpressionType::Decltype);
ExprResult E = getDerived().TransformExpr(T->getUnderlyingExpr());
if (E.isInvalid())
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -6195,7 +6195,7 @@
if (RD->isInvalidDecl() || RD->isDependentContext())
return E;
- bool IsDecltype = ExprEvalContexts.back().IsDecltype;
+ bool IsDecltype = ExprEvalContexts.back().Type == ExpressionType::Decltype;
CXXDestructorDecl *Destructor = IsDecltype ? nullptr : LookupDestructor(RD);
if (Destructor) {
@@ -6277,7 +6277,8 @@
/// are omitted for the 'topmost' call in the decltype expression. If the
/// topmost call bound a temporary, strip that temporary off the expression.
ExprResult Sema::ActOnDecltypeExpression(Expr *E) {
- assert(ExprEvalContexts.back().IsDecltype && "not in a decltype expression");
+ assert(ExprEvalContexts.back().Type == ExpressionType::Decltype &&
+ "not in a decltype expression");
// C++11 [expr.call]p11:
// If a function call is a prvalue of object type,
@@ -6319,7 +6320,7 @@
TopBind = nullptr;
// Disable the special decltype handling now.
- ExprEvalContexts.back().IsDecltype = false;
+ ExprEvalContexts.back().Type = ExpressionType::Other;
// In MS mode, don't perform any extra checking of call return types within a
// decltype expression.
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -13703,51 +13703,50 @@
void
Sema::PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
Decl *LambdaContextDecl,
- bool IsDecltype) {
+ ExpressionType Type) {
ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(), Cleanup,
- LambdaContextDecl, IsDecltype);
+ LambdaContextDecl, Type);
Cleanup.reset();
if (!MaybeODRUseExprs.empty())
std::swap(MaybeODRUseExprs, ExprEvalContexts.back().SavedMaybeODRUseExprs);
}
void
Sema::PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
ReuseLambdaContextDecl_t,
- bool IsDecltype) {
+ ExpressionType Type) {
Decl *ClosureContextDecl = ExprEvalContexts.back().ManglingContextDecl;
- PushExpressionEvaluationContext(NewContext, ClosureContextDecl, IsDecltype);
+ PushExpressionEvaluationContext(NewContext, ClosureContextDecl, Type);
}
void Sema::PopExpressionEvaluationContext() {
ExpressionEvaluationContextRecord& Rec = ExprEvalContexts.back();
unsigned NumTypos = Rec.NumTypos;
if (!Rec.Lambdas.empty()) {
- if (Rec.isUnevaluated() || Rec.isConstantEvaluated()) {
+ if (Rec.Type == ExpressionType::TemplateParameter || Rec.isUnevaluated() ||
+ (Rec.isConstantEvaluated() && !getLangOpts().CPlusPlus17)) {
unsigned D;
if (Rec.isUnevaluated()) {
// C++11 [expr.prim.lambda]p2:
// A lambda-expression shall not appear in an unevaluated operand
// (Clause 5).
D = diag::err_lambda_unevaluated_operand;
- } else {
+ } else if (Rec.isConstantEvaluated() && !getLangOpts().CPlusPlus17) {
// C++1y [expr.const]p2:
// A conditional-expression e is a core constant expression unless the
// evaluation of e, following the rules of the abstract machine, would
// evaluate [...] a lambda-expression.
D = diag::err_lambda_in_constant_expression;
- }
+ } else if (Rec.Type == ExpressionType::TemplateParameter) {
+ // C++17 [expr.prim.lamda]p2:
+ // A lambda-expression shall not appear [...] in a template-argument.
+ D = diag::err_lambda_in_invalid_context;
+ } else
+ llvm_unreachable("Couldn't infer lambda error message.");
- // C++1z allows lambda expressions as core constant expressions.
- // FIXME: In C++1z, reinstate the restrictions on lambda expressions (CWG
- // 1607) from appearing within template-arguments and array-bounds that
- // are part of function-signatures. Be mindful that P0315 (Lambdas in
- // unevaluated contexts) might lift some of these restrictions in a
- // future version.
- if (!Rec.isConstantEvaluated() || !getLangOpts().CPlusPlus17)
- for (const auto *L : Rec.Lambdas)
- Diag(L->getLocStart(), D);
+ for (const auto *L : Rec.Lambdas)
+ Diag(L->getLocStart(), D);
} else {
// Mark the capture expressions odr-used. This was deferred
// during lambda expression creation.
@@ -15229,7 +15228,7 @@
// If we're inside a decltype's expression, don't check for a valid return
// type or construct temporaries until we know whether this is the last call.
- if (ExprEvalContexts.back().IsDecltype) {
+ if (ExprEvalContexts.back().Type == ExpressionType::Decltype) {
ExprEvalContexts.back().DelayedDecltypeCalls.push_back(CE);
return false;
}
Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -159,7 +159,7 @@
ExprEvalContexts.emplace_back(
ExpressionEvaluationContext::PotentiallyEvaluated, 0, CleanupInfo{},
- nullptr, false);
+ nullptr, ExpressionType::Other);
FunctionScopes.push_back(new FunctionScopeInfo(Diags));
Index: lib/Parse/ParseTemplate.cpp
===================================================================
--- lib/Parse/ParseTemplate.cpp
+++ lib/Parse/ParseTemplate.cpp
@@ -1191,7 +1191,9 @@
// argument before trying to disambiguate.
EnterExpressionEvaluationContext EnterConstantEvaluated(
- Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+ Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated,
+ /*LambdaContextDecl=*/nullptr,
+ /*Type=*/Sema::ExpressionType::TemplateParameter);
if (isCXXTypeId(TypeIdAsTemplateArgument)) {
SourceLocation Loc = Tok.getLocation();
TypeResult TypeArg = ParseTypeName(
Index: lib/Parse/ParseStmt.cpp
===================================================================
--- lib/Parse/ParseStmt.cpp
+++ lib/Parse/ParseStmt.cpp
@@ -1196,7 +1196,7 @@
{
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Sema::ExpressionEvaluationContext::DiscardedStatement, nullptr,
- false,
+ Sema::ExpressionType::Other,
/*ShouldEnter=*/ConstexprCondition && !*ConstexprCondition);
ThenStmt = ParseStatement(&InnerStatementTrailingElseLoc);
}
@@ -1230,7 +1230,7 @@
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Sema::ExpressionEvaluationContext::DiscardedStatement, nullptr,
- false,
+ Sema::ExpressionType::Other,
/*ShouldEnter=*/ConstexprCondition && *ConstexprCondition);
ElseStmt = ParseStatement();
Index: lib/Parse/ParseDeclCXX.cpp
===================================================================
--- lib/Parse/ParseDeclCXX.cpp
+++ lib/Parse/ParseDeclCXX.cpp
@@ -942,7 +942,7 @@
// The operand of the decltype specifier is an unevaluated operand.
EnterExpressionEvaluationContext Unevaluated(
Actions, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
- /*IsDecltype=*/true);
+ Sema::ExpressionType::Decltype);
Result =
Actions.CorrectDelayedTyposInExpr(ParseExpression(), [](Expr *E) {
return E->hasPlaceholderType() ? ExprError() : E;
Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -310,9 +310,7 @@
EnterExpressionEvaluationContext Unevaluated(
Actions,
Uneval ? Sema::ExpressionEvaluationContext::Unevaluated
- : Sema::ExpressionEvaluationContext::ConstantEvaluated,
- /*LambdaContextDecl=*/nullptr,
- /*IsDecltype=*/false);
+ : Sema::ExpressionEvaluationContext::ConstantEvaluated);
ExprResult ArgExpr(
Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression()));
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -932,6 +932,12 @@
PotentiallyEvaluatedIfUsed
};
+ /// \brief Describes whether we are in an expression that needs
+ /// special handling.
+ enum class ExpressionType {
+ Decltype, TemplateParameter, Other
+ };
+
/// \brief Data structure used to record current or nested
/// expression evaluation contexts.
struct ExpressionEvaluationContextRecord {
@@ -941,8 +947,9 @@
/// \brief Whether the enclosing context needed a cleanup.
CleanupInfo ParentCleanup;
- /// \brief Whether we are in a decltype expression.
- bool IsDecltype;
+ /// \brief Whether this is a type of expression that needs
+ /// separate handling from other expressions.
+ ExpressionType Type;
/// \brief The number of active cleanup objects when we entered
/// this expression evaluation context.
@@ -982,11 +989,10 @@
unsigned NumCleanupObjects,
CleanupInfo ParentCleanup,
Decl *ManglingContextDecl,
- bool IsDecltype)
- : Context(Context), ParentCleanup(ParentCleanup),
- IsDecltype(IsDecltype), NumCleanupObjects(NumCleanupObjects),
- NumTypos(0),
- ManglingContextDecl(ManglingContextDecl), MangleNumbering() { }
+ ExpressionType Type)
+ : Context(Context), ParentCleanup(ParentCleanup), Type(Type),
+ NumCleanupObjects(NumCleanupObjects), NumTypos(0),
+ ManglingContextDecl(ManglingContextDecl), MangleNumbering() {}
/// \brief Retrieve the mangling numbering context, used to consistently
/// number constructs like lambdas for mangling.
@@ -3971,11 +3977,11 @@
void PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
Decl *LambdaContextDecl = nullptr,
- bool IsDecltype = false);
+ ExpressionType Type = ExpressionType::Other);
enum ReuseLambdaContextDecl_t { ReuseLambdaContextDecl };
void PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext,
ReuseLambdaContextDecl_t,
- bool IsDecltype = false);
+ ExpressionType Type = ExpressionType::Other);
void PopExpressionEvaluationContext();
void DiscardCleanupsInEvaluationContext();
@@ -10646,21 +10652,20 @@
EnterExpressionEvaluationContext(Sema &Actions,
Sema::ExpressionEvaluationContext NewContext,
Decl *LambdaContextDecl = nullptr,
- bool IsDecltype = false,
+ Sema::ExpressionType Type = Sema::ExpressionType::Other,
bool ShouldEnter = true)
: Actions(Actions), Entered(ShouldEnter) {
if (Entered)
Actions.PushExpressionEvaluationContext(NewContext, LambdaContextDecl,
- IsDecltype);
+ Type);
}
EnterExpressionEvaluationContext(Sema &Actions,
Sema::ExpressionEvaluationContext NewContext,
Sema::ReuseLambdaContextDecl_t,
- bool IsDecltype = false)
+ Sema::ExpressionType Type = Sema::ExpressionType::Other)
: Actions(Actions) {
Actions.PushExpressionEvaluationContext(NewContext,
- Sema::ReuseLambdaContextDecl,
- IsDecltype);
+ Sema::ReuseLambdaContextDecl, Type);
}
enum InitListTag { InitList };
@@ -10674,7 +10679,7 @@
if (ShouldEnter && Actions.isUnevaluatedContext() &&
Actions.getLangOpts().CPlusPlus11) {
Actions.PushExpressionEvaluationContext(
- Sema::ExpressionEvaluationContext::UnevaluatedList, nullptr, false);
+ Sema::ExpressionEvaluationContext::UnevaluatedList);
Entered = true;
}
}
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -6565,6 +6565,8 @@
"lambda expression in an unevaluated operand">;
def err_lambda_in_constant_expression : Error<
"a lambda expression may not appear inside of a constant expression">;
+ def err_lambda_in_invalid_context : Error<
+ "a lambda expression cannot appear in this context">;
def err_lambda_return_init_list : Error<
"cannot deduce lambda return type from initializer list">;
def err_lambda_capture_default_arg : Error<
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