From f9c8f0da020820997c2d2394c07e834a33994aab Mon Sep 17 00:00:00 2001
From: Hannes Vogt <hannes@havogt.de>
Date: Sat, 3 Nov 2018 22:01:29 +0100
Subject: [PATCH] Bug 540676 - Improve parsing of alias templates

- If the argument for a template template paramter is unknown
(ICPPUnknownType), don't create a problem.
- Ensure that a possible argument-parameter mismatch is caught at
template instantiation time.

Change-Id: Ief61ef93f9d0c19d043aedb89f1c5e66c0374ef2
Signed-off-by: Hannes Vogt <hannes@havogt.de>
---
 .../parser/tests/ast2/AST2TemplateTests.java  | 40 +++++++++++++++++++
 .../parser/cpp/semantics/CPPTemplates.java    | 12 ++++--
 2 files changed, 49 insertions(+), 3 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 e4390872b85..7e5d6696e60 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
@@ -10984,4 +10984,44 @@ public class AST2TemplateTests extends AST2CPPTestBase {
 	public void testDependentTemplateTemplateArgument_540450() throws Exception {
 		parseAndCheckBindings();
 	}
+
+	//	struct type{};
+	//
+	//	template <template <class> class T1>
+	//	using template_template_alias = type;
+	//
+	//	template<typename T2>
+	//	struct foo{
+	//		template <typename T3>
+	//		struct apply{};
+	//	};
+	//
+	//	template <class T4>
+	//	using trigger = template_template_alias<foo<T4>::template apply>;
+	public void testAliasTemplateWithTemplateTemplateParameter_540676() throws Exception {
+		parseAndCheckBindings();
+	}
+
+	//	struct type{};
+	//
+	//	template <template <class, class> class T1> // number of arguments doesn't match
+	//	using template_template_alias = type;
+	//
+	//	template<typename T2>
+	//	struct foo{
+	//		template <typename T3>
+	//		struct apply{};
+	//	};
+	//
+	//	template <class T4>
+	//	using trigger = template_template_alias<foo<T4>::template apply>;
+	//
+	//	using A = trigger<type>;
+	//
+	//	template <typename> struct B;
+	//	using C = B<A>;
+	public void testInvalidAliasTemplateWithTemplateTemplateParameter_540676() throws Exception {
+		BindingAssertionHelper bh= new AST2AssertionHelper(getAboveComment(), CPP);
+		bh.assertProblem("B<A>", 4);
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java
index 89c30f2a77c..12d2321b5f8 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java
@@ -1629,9 +1629,13 @@ public class CPPTemplates {
 							IProblemBinding.SEMANTIC_INVALID_TEMPLATE_ARGUMENTS);
 				} else if (args != newArgs) {
 					IType target = instantiateType(instance.getType(), context);
-					CPPTemplateParameterMap map = 
-							instantiateArgumentMap(instance.getTemplateParameterMap(), context);
-					result = new CPPAliasTemplateInstance(template, target, instance.getOwner(), map, newArgs);
+					CPPTemplateParameterMap map = createParameterMap(template, newArgs);
+					if (map == null) {
+						result = (IType) createProblem(template,
+								IProblemBinding.SEMANTIC_INVALID_TEMPLATE_ARGUMENTS);
+					} else {
+						result = new CPPAliasTemplateInstance(template, target, instance.getOwner(), map, newArgs);
+					}
 				} else {
 					result = type;
 				}
@@ -2737,6 +2741,8 @@ public class CPPTemplates {
 
 		if (param instanceof ICPPTemplateTemplateParameter) {
 			IType t= arg.getTypeValue();
+			if (t instanceof ICPPUnknownType)
+				return arg;
 			while (!(t instanceof ICPPTemplateDefinition)) {
 				if (t instanceof ICPPClassSpecialization) {
 					// Undo the effect of specializing a template when the unqualified name