[Clang] only inherit the parent eval context inside of lambdas

[cor3ntin]

As we create defaul constructors lazily, we should not inherit from the parent evaluation context.
However, we need to make an exception for lambdas (in particular their conversion operators, which are also implicitly defined).

As a drive-by, we introduce a generic way to query whether a function is a member of a lambda.

This fixes a regression introduced by baf6bd3.

Fixes #118000

[llvmbot]

@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-clang

Author: cor3ntin (cor3ntin)

Changes

As we create defaul constructors lazily, we should not inherit from the parent evaluation context.
However, we need to make an exception for lambdas (in particular their conversion operators, which are also implicitly defined).

As a drive-by, we introduce a generic way to query whether a function is a member of a lambda.

This fixes a regression introduced by baf6bd3.

Fixes #118000

---

Full diff: https://github.com/llvm/llvm-project/pull/124426.diff

8 Files Affected:

• (modified) clang/include/clang/AST/ASTLambda.h (+7)
• (modified) clang/include/clang/Sema/Sema.h (+9-6)
• (modified) clang/lib/AST/ASTImporter.cpp (+2-4)
• (modified) clang/lib/AST/Expr.cpp (+1-2)
• (modified) clang/lib/CodeGen/CGExpr.cpp (+2-2)
• (modified) clang/lib/Sema/SemaDeclCXX.cpp (+1-2)
• (modified) clang/lib/Sema/SemaTemplateInstantiateDecl.cpp (+1-2)
• (modified) clang/test/SemaCXX/cxx2b-consteval-propagate.cpp (+16)

diff --git a/clang/include/clang/AST/ASTLambda.h b/clang/include/clang/AST/ASTLambda.h
index 646cb574847fe2..50a828870501a3 100644
--- a/clang/include/clang/AST/ASTLambda.h
+++ b/clang/include/clang/AST/ASTLambda.h
@@ -17,6 +17,7 @@
 
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
+#include "llvm/Support/Casting.h"
 
 namespace clang {
 inline StringRef getLambdaStaticInvokerName() {
@@ -35,6 +36,12 @@ inline bool isLambdaCallOperator(const DeclContext *DC) {
   return isLambdaCallOperator(cast<CXXMethodDecl>(DC));
 }
 
+inline bool isLambdaMethod(const DeclContext *DC) {
+  if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(DC); MD)
+    return MD->getParent()->isLambda();
+  return false;
+}
+
 inline bool isLambdaCallWithExplicitObjectParameter(const DeclContext *DC) {
   return isLambdaCallOperator(DC) &&
          cast<CXXMethodDecl>(DC)->isExplicitObjectMemberFunction();
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 4d6e02fe2956e0..56a987146a18b3 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -16,6 +16,7 @@
 
 #include "clang/APINotes/APINotesManager.h"
 #include "clang/AST/ASTFwd.h"
+#include "clang/AST/ASTLambda.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/AttrIterator.h"
 #include "clang/AST/CharUnits.h"
@@ -13108,14 +13109,16 @@ class Sema final : public SemaBase {
               ? ExpressionEvaluationContext::ImmediateFunctionContext
               : ExpressionEvaluationContext::PotentiallyEvaluated);
       if (FD) {
+        auto &Current = S.currentEvaluationContext(),
+             Parent = S.parentEvaluationContext();
+
         FD->setWillHaveBody(true);
-        S.ExprEvalContexts.back().InImmediateFunctionContext =
+        Current.InImmediateFunctionContext =
             FD->isImmediateFunction() ||
-            S.ExprEvalContexts[S.ExprEvalContexts.size() - 2]
-                .isConstantEvaluated() ||
-            S.ExprEvalContexts[S.ExprEvalContexts.size() - 2]
-                .isImmediateFunctionContext();
-        S.ExprEvalContexts.back().InImmediateEscalatingFunctionContext =
+            (isLambdaMethod(FD) && (Parent.isConstantEvaluated() ||
+                                    Parent.isImmediateFunctionContext()));
+
+        Current.InImmediateEscalatingFunctionContext =
             S.getLangOpts().CPlusPlus20 && FD->isImmediateEscalating();
       } else
         assert(isa<ObjCMethodDecl>(DC));
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 0669aa1b809c34..5dfd9fcee02159 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTDiagnostic.h"
 #include "clang/AST/ASTImporterSharedState.h"
+#include "clang/AST/ASTLambda.h"
 #include "clang/AST/ASTStructuralEquivalence.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/Decl.h"
@@ -3729,10 +3730,7 @@ bool ASTNodeImporter::hasReturnTypeDeclaredInside(FunctionDecl *D) {
     if (Importer.FromContext.getLangOpts().CPlusPlus14) // C++14 or later
       return false;
 
-    if (const auto *MD = dyn_cast<CXXMethodDecl>(D))
-      return cast<CXXRecordDecl>(MD->getDeclContext())->isLambda();
-
-    return false;
+    return isLambdaMethod(D);
   };
 
   QualType RetT = FromFPT->getReturnType();
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 31b95bca613c21..06b04914426737 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -895,8 +895,7 @@ std::string PredefinedExpr::ComputeName(PredefinedIdentKind IK,
     // type deduction and lambdas. For trailing return types resolve the
     // decltype expression. Otherwise print the real type when this is
     // not a constructor or destructor.
-    if (isa<CXXMethodDecl>(FD) &&
-         cast<CXXMethodDecl>(FD)->getParent()->isLambda())
+    if (isLambdaMethod(FD))
       Proto = "auto " + Proto;
     else if (FT && FT->getReturnType()->getAs<DecltypeType>())
       FT->getReturnType()
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 054f8d1eadb8c5..28c52690916393 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -24,6 +24,7 @@
 #include "ConstantEmitter.h"
 #include "TargetInfo.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTLambda.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/NSAPI.h"
@@ -1809,8 +1810,7 @@ CodeGenFunction::tryEmitAsConstant(DeclRefExpr *refExpr) {
   if (CGM.getLangOpts().CUDAIsDevice && result.Val.isLValue() &&
       refExpr->refersToEnclosingVariableOrCapture()) {
     auto *MD = dyn_cast_or_null<CXXMethodDecl>(CurCodeDecl);
-    if (MD && MD->getParent()->isLambda() &&
-        MD->getOverloadedOperator() == OO_Call) {
+    if (isLambdaMethod(MD) && MD->getOverloadedOperator() == OO_Call) {
       const APValue::LValueBase &base = result.Val.getLValueBase();
       if (const ValueDecl *D = base.dyn_cast<const ValueDecl *>()) {
         if (const VarDecl *VD = dyn_cast<const VarDecl>(D)) {
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 08065e3cad2bb3..c803e1fba43d3c 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -13855,8 +13855,7 @@ void Sema::setupImplicitSpecialMemberType(CXXMethodDecl *SpecialMem,
   // During template instantiation of implicit special member functions we need
   // a reliable TypeSourceInfo for the function prototype in order to allow
   // functions to be substituted.
-  if (inTemplateInstantiation() &&
-      cast<CXXRecordDecl>(SpecialMem->getParent())->isLambda()) {
+  if (inTemplateInstantiation() && isLambdaMethod(SpecialMem)) {
     TypeSourceInfo *TSI =
         Context.getTrivialTypeSourceInfo(SpecialMem->getType());
     SpecialMem->setTypeSourceInfo(TSI);
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 6a2331e59477a2..b3dcb12c4c8352 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2606,8 +2606,7 @@ Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(
   // conditionally populate the TSI without breaking non-template related use
   // cases. Populate TSIs prior to calling SubstFunctionType to make sure we get
   // a proper transformation.
-  if (cast<CXXRecordDecl>(D->getParent())->isLambda() &&
-      !D->getTypeSourceInfo() &&
+  if (isLambdaMethod(D) && !D->getTypeSourceInfo() &&
       isa<CXXConstructorDecl, CXXDestructorDecl>(D)) {
     TypeSourceInfo *TSI =
         SemaRef.Context.getTrivialTypeSourceInfo(D->getType());
diff --git a/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp b/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
index 3f3123eaee76b6..aeae82d63b696d 100644
--- a/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
+++ b/clang/test/SemaCXX/cxx2b-consteval-propagate.cpp
@@ -528,3 +528,19 @@ D d(0); // expected-note {{in implicit initialization for inherited constructor
 // expected-error@-1 {{call to immediate function 'GH112677::D::SimpleCtor' is not a constant expression}}
 
 }
+
+
+namespace GH118000 {
+consteval int baz() { return 0;}
+struct S {
+    int mSize = baz();
+};
+
+consteval void bar() {
+    S s;
+}
+
+void foo() {
+    S s;
+}
+}

[Sirraide]

Suggested change

	auto &Current = S.currentEvaluationContext(),
	Parent = S.parentEvaluationContext();
	auto &Current = S.currentEvaluationContext();
	auto &Parent = S.parentEvaluationContext();

I think this is a bit clearer, because I don’t think you meant to copy the parent evaluation context here, right?

[tbaederr]

Suggested change

	if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(DC); MD)
	if (const auto *MD = dyn_cast_if_present<CXXMethodDecl>(DC))