r369722 - PR42587: diagnose unexpanded uses of a pack parameter of a generic

[Richard Smith via cfe-commits]

Author: rsmith
Date: Thu Aug 22 18:41:48 2019
New Revision: 369722

URL: http://llvm.org/viewvc/llvm-project?rev=369722&view=rev
Log:
PR42587: diagnose unexpanded uses of a pack parameter of a generic
lambda from within the lambda-declarator.

Modified:
    cfe/trunk/lib/Sema/SemaLambda.cpp
    cfe/trunk/lib/Sema/SemaTemplateVariadic.cpp
    cfe/trunk/test/SemaCXX/cxx1y-generic-lambdas-variadics.cpp

Modified: cfe/trunk/lib/Sema/SemaLambda.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLambda.cpp?rev=369722&r1=369721&r2=369722&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaLambda.cpp (original)
+++ cfe/trunk/lib/Sema/SemaLambda.cpp Thu Aug 22 18:41:48 2019
@@ -928,12 +928,12 @@ void Sema::ActOnStartOfLambdaDefinition(
 
     // Check for unexpanded parameter packs in the method type.
     if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
-      ContainsUnexpandedParameterPack = true;
+      DiagnoseUnexpandedParameterPack(Intro.Range.getBegin(), MethodTyInfo,
+                                      UPPC_DeclarationType);
   }
 
   CXXRecordDecl *Class = createLambdaClosureType(Intro.Range, MethodTyInfo,
                                                  KnownDependent, Intro.Default);
-
   CXXMethodDecl *Method =
       startLambdaDefinition(Class, Intro.Range, MethodTyInfo, EndLoc, Params,
                             ParamInfo.getDeclSpec().getConstexprSpecifier());

Modified: cfe/trunk/lib/Sema/SemaTemplateVariadic.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateVariadic.cpp?rev=369722&r1=369721&r2=369722&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateVariadic.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateVariadic.cpp Thu Aug 22 18:41:48 2019
@@ -313,10 +313,17 @@ Sema::DiagnoseUnexpandedParameterPacks(S
 
     if (auto *LSI = dyn_cast<sema::LambdaScopeInfo>(Func)) {
       if (N == FunctionScopes.size()) {
+        const DeclContext *LambdaDC = LSI->CallOperator;
+        // While we're parsing the lambda-declarator, we don't have a call
+        // operator yet and the parameters instead get temporarily attached
+        // to the translation unit.
+        if (!LambdaDC)
+          LambdaDC = Context.getTranslationUnitDecl();
+
         for (auto &Pack : Unexpanded) {
           auto *VD = dyn_cast_or_null<VarDecl>(
               Pack.first.dyn_cast<NamedDecl *>());
-          if (VD && VD->getDeclContext() == LSI->CallOperator)
+          if (VD && VD->getDeclContext() == LambdaDC)
             LambdaParamPackReferences.push_back(Pack);
         }
       }

Modified: cfe/trunk/test/SemaCXX/cxx1y-generic-lambdas-variadics.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx1y-generic-lambdas-variadics.cpp?rev=369722&r1=369721&r2=369722&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/cxx1y-generic-lambdas-variadics.cpp (original)
+++ cfe/trunk/test/SemaCXX/cxx1y-generic-lambdas-variadics.cpp Thu Aug 22 18:41:48 2019
@@ -122,3 +122,11 @@ namespace PR33082 {
     b(Pack<int*, float*>(), 1, 2, 3); // expected-note {{instantiation of}}
   }
 }
+
+void pr42587() {
+  (void)[](auto... args) -> decltype(args) {}; // expected-error {{type contains unexpanded parameter pack}}
+  (void)[](auto... args, int = args) {}; // expected-error {{default argument contains unexpanded parameter pack}}
+  (void)[](auto... args, decltype(args)) {}; // expected-error {{type contains unexpanded parameter pack}}
+  (void)[](auto... args, decltype(args)...) {}; // (ok)
+  (void)[](auto... args, int = [=] { return args; }()) {}; // expected-error {{default argument contains unexpanded parameter pack}}
+}