From 1370c76c3875d3d0ca88d81c8551f77d6d269dbd Mon Sep 17 00:00:00 2001
From: Hannes Vogt <hannes@havogt.de>
Date: Tue, 26 Feb 2019 23:31:25 +0100
Subject: [PATCH] Bug 544681 - Support for template<auto...>

Change-Id: I059d69ee86603c1aed95eeed1be61b915df6e3ed
Signed-off-by: Hannes Vogt <hannes@havogt.de>
---
 .../parser/tests/ast2/AST2TemplateTests.java  | 22 +++++++++++++++++++
 .../cpp/CPPTemplateNonTypeParameter.java      | 17 ++++++++++----
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java
index 7872bd93ab5..1323628a656 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java
@@ -11260,4 +11260,26 @@ public class AST2TemplateTests extends AST2CPPTestBase {
 		bh.assertProblem("foo(0)", 3);
 	}
 
+	//  template <auto First, auto...>
+	//  struct getFirst {
+	//      static constexpr auto value = First;
+	//  };
+	//  template <auto, auto Second, auto...>
+	//  struct getSecond {
+	//      static constexpr auto value = Second;
+	//  };
+	//	template <auto... T>
+	//	struct A {
+	//	    static constexpr auto first = getFirst<T...>::value;
+	//	    static constexpr auto second = getSecond<T...>::value;
+	//	};
+	//
+	//	typedef A<42,43> B;
+	//  static constexpr auto val1 = B::first;
+	//  static constexpr auto val2 = B::second;
+	public void testVariadicTemplateAuto_544681() throws Exception {
+		BindingAssertionHelper helper = getAssertionHelper();
+		helper.assertVariableValue("val1", 42);
+		helper.assertVariableValue("val2", 43);
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPTemplateNonTypeParameter.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPTemplateNonTypeParameter.java
index 9d960cdddb3..3c881e21329 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPTemplateNonTypeParameter.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPTemplateNonTypeParameter.java
@@ -120,15 +120,24 @@ public class CPPTemplateNonTypeParameter extends CPPTemplateParameter implements
 
 			// C++17 template<auto>
 			if (type instanceof CPPPlaceholderType) {
-				CPPDependentEvaluation eval = new EvalBinding(this, null, getPrimaryDeclaration());
-				TypeOfDependentExpression replacementType = new TypeOfDependentExpression(eval);
-				replacementType.setForTemplateAuto(true);
-				type = replacementType;
+				type = getDependentTypeForAuto();
+			}
+			// template<auto...>
+			if (type instanceof CPPParameterPackType
+					&& ((CPPParameterPackType) type).getType() instanceof CPPPlaceholderType) {
+				type = new CPPParameterPackType(getDependentTypeForAuto());
 			}
 		}
 		return type;
 	}
 
+	private IType getDependentTypeForAuto() {
+		CPPDependentEvaluation eval = new EvalBinding(this, null, getPrimaryDeclaration());
+		TypeOfDependentExpression replacementType = new TypeOfDependentExpression(eval);
+		replacementType.setForTemplateAuto(true);
+		return replacementType;
+	}
+
 	@Override
 	public boolean isParameterPack() {
 		return getType() instanceof ICPPParameterPackType;