[SYCL][clang] Always lift SYCL device code restrictions in constant expressions

clang/include/clang/Basic/LangOptions.def

@@ -307,7 +307,6 @@ LANGOPT(SYCLAllowFuncPtr  , 1, 0, "Allow function pointers in SYCL device code")
 LANGOPT(SYCLStdLayoutKernelParams, 1, 0, "Enable standard layout requirement for SYCL kernel parameters")
 LANGOPT(SYCLUnnamedLambda , 1, 0, "Allow unnamed lambda SYCL kernels")
 LANGOPT(SYCLForceInlineKernelLambda , 1, 0, "Force inline SYCL kernel lambdas in entry point")
-LANGOPT(SYCLAllowAllFeaturesInConstexpr, 1, 0, "Allow all C++ features in SYCL device code in manifestly constant-evaluated expressions")
 LANGOPT(SYCLESIMDForceStatelessMem, 1, 0, "Make accessors use USM memory in ESIMD kernels")
 LANGOPT(SYCLESIMDBuildHostCode, 1, 1, "Build the host implementation of ESIMD functions")
 ENUM_LANGOPT(SYCLVersion  , SYCLMajorVersion, 2, SYCL_None, "Version of the SYCL standard used")

clang/include/clang/Driver/Options.td

@@ -8628,11 +8628,6 @@ def fsycl_is_native_cpu : Flag<["-"], "fsycl-is-native-cpu">,
   HelpText<"Perform device compilation for Native CPU.">,
   Visibility<[CC1Option]>,
   MarshallingInfoFlag<LangOpts<"SYCLIsNativeCPU">>;
-defm sycl_allow_all_features_in_constexpr
-    : BoolFOption<
-          "sycl-allow-all-features-in-constexpr", LangOpts<"SYCLAllowAllFeaturesInConstexpr">,
-          DefaultFalse,
-          PosFlag<SetTrue, [], [CC1Option], "Allow all C++ features in SYCL device code in manifestly constant-evaluated expressions">, NegFlag<SetFalse>>;
 
 } // let Visibility = [CC1Option]
 

clang/lib/Sema/Sema.cpp

@@ -1829,7 +1829,7 @@ class DeferredDiagnosticsEmitter
   }
 
   void VisitDeclStmt(DeclStmt *DS) {
-    if (S.getLangOpts().SYCLAllowAllFeaturesInConstexpr) {
+    if (S.getLangOpts().SYCLIsDevice) {
       if (DS->isSingleDecl()) {
         Decl *D = DS->getSingleDecl();
         if (auto *VD = dyn_cast<VarDecl>(D))
@@ -1850,7 +1850,7 @@ class DeferredDiagnosticsEmitter
   }
 
   void VisitConstantExpr(ConstantExpr *E) {
-    if (S.getLangOpts().SYCLAllowAllFeaturesInConstexpr)
+    if (S.getLangOpts().SYCLIsDevice)
       return;
     this->VisitStmt(E);
   }
@@ -2264,7 +2264,7 @@ void Sema::checkTypeSupport(QualType Ty, SourceLocation Loc, ValueDecl *D) {
 
   CheckType(Ty);
   if (const auto *FD = dyn_cast_if_present<FunctionDecl>(D)) {
-    if (LangOpts.SYCLAllowAllFeaturesInConstexpr && FD->isConsteval())
+    if (LangOpts.SYCLIsDevice && FD->isConsteval())
       return;
     if (const auto *FPTy = dyn_cast<FunctionProtoType>(Ty)) {
       for (const auto &ParamTy : FPTy->param_types())

clang/lib/Sema/SemaDeclCXX.cpp

@@ -18418,7 +18418,7 @@ void Sema::ActOnCXXEnterDeclInitializer(Scope *S, Decl *D) {
 
   if (auto *VD = dyn_cast<VarDecl>(D);
       VD && (VD->mightBeUsableInConstantExpressions(Context)))
-    InConstexprVarInit = LangOpts.SYCLAllowAllFeaturesInConstexpr;
+    InConstexprVarInit = true;
   PushExpressionEvaluationContext(
       ExpressionEvaluationContext::PotentiallyEvaluated, D);
 }

clang/lib/Sema/SemaSYCL.cpp

@@ -782,8 +782,7 @@ class DeviceFunctionTracker {
 
 public:
   DeviceFunctionTracker(SemaSYCL &S) : SemaSYCLRef(S) {
-    if (S.getLangOpts().SYCLAllowAllFeaturesInConstexpr)
-      CG.setSkipConstantExpressions(S.getASTContext());
+    CG.setSkipConstantExpressions(S.getASTContext());
     CG.addToCallGraph(S.getASTContext().getTranslationUnitDecl());
     CollectSyclExternalFuncs();
   }
@@ -5594,14 +5593,12 @@ SemaSYCL::DiagIfDeviceCode(SourceLocation Loc, unsigned DiagID,
       return SemaDiagnosticBuilder::K_ImmediateWithCallStack;
     if (!FD)
       return SemaDiagnosticBuilder::K_Nop;
-    if (SemaRef.getLangOpts().SYCLAllowAllFeaturesInConstexpr &&
-        (SemaRef.isConstantEvaluatedContext() ||
-         SemaRef.currentEvaluationContext().isDiscardedStatementContext()))
+    if (SemaRef.isConstantEvaluatedContext() ||
+        SemaRef.currentEvaluationContext().isDiscardedStatementContext())
       return SemaDiagnosticBuilder::K_Nop;
     // Defer until we know that the variable's intializer is actually a
     // manifestly constant-evaluated expression.
-    if (SemaRef.getLangOpts().SYCLAllowAllFeaturesInConstexpr &&
-        SemaRef.InConstexprVarInit)
+    if (SemaRef.InConstexprVarInit)
       return SemaDiagnosticBuilder::K_Deferred;
     if (SemaRef.getEmissionStatus(FD) ==
         Sema::FunctionEmissionStatus::Emitted) {

clang/test/SemaSYCL/allow-all-features-in-constexpr.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsycl-is-device -internal-isystem %S/Inputs -fcxx-exceptions -verify -fsyntax-only -std=c++23 -triple spir64 -aux-triple x86_64 -fsycl-allow-all-features-in-constexpr %s
+// RUN: %clang_cc1 -fsycl-is-device -internal-isystem %S/Inputs -fcxx-exceptions -verify -fsyntax-only -std=c++23 -triple spir64 -aux-triple x86_64 %s
 
 // The test checks that all SYCL device code limitations are lifted in
 // manifestly constant-evaluated expressions under an option.

clang/test/SemaSYCL/wrong-address-taking.cpp

@@ -50,7 +50,6 @@ template <typename T> void templatedContext() {
   // expected-error@+1 {{taking address of a function not marked with 'intel::device_indirectly_callable' attribute is not allowed in SYCL device code}}
   auto p1 = &ForMembers::badMember;
 
-  // expected-error@+2 {{taking address of a function not marked with 'intel::device_indirectly_callable' attribute is not allowed in SYCL device code}}
   // expected-note@+1 {{called by 'templatedContext<int>'}}
   templateCaller1<badFoo>(1);
 }
@@ -84,9 +83,7 @@ int main() {
           a = goodFoo;
           a = &goodFoo;
 
-          // expected-error@+1 {{taking address of a function not marked with 'intel::device_indirectly_callable' attribute is not allowed in SYCL device code}}
           constexpr auto b = badFoo;
-          // expected-error@+1 {{taking address of a function not marked with 'intel::device_indirectly_callable' attribute is not allowed in SYCL device code}}
           constexpr auto c = &badFoo;
           // expected-note@+1 {{called by 'operator()'}}
           basicUsage();
@@ -125,8 +122,7 @@ int main() {
 
           templateCaller1<goodFoo>(1);
 
-          // expected-note@+2 {{called by 'operator()'}}
-          // expected-error@+1 {{taking address of a function not marked with 'intel::device_indirectly_callable' attribute is not allowed in SYCL device code}}
+          // expected-note@+1 {{called by 'operator()'}}
           templateCaller1<badFoo>(1);
         });
   });