From 87db7de76505c9fbb945a5f5af8aa22a9e0e6b0d Mon Sep 17 00:00:00 2001
From: Nathan Ridge <zeratul976@hotmail.com>
Date: Sun, 23 Apr 2017 17:27:53 -0400
Subject: [PATCH] Bug 515453 - Clear all ProblemBindings stored during
 ambiguity resolution

This prevents names getting incorrectly stuck with ProblemBindings
created at a time when the AST wasn't fully ambiguity-resolved yet.

Change-Id: Ibca4a774ee26c393bf2b6decb535b82a2329caad
---
 .../parser/tests/ast2/AST2TemplateTests.java  | 17 +++++++++++++++++
 .../dom/parser/cpp/CPPASTTranslationUnit.java | 19 +++++++++++++++++++
 2 files changed, 36 insertions(+)

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 fbd78fe3cd2..29ccee449d1 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
@@ -9867,6 +9867,23 @@ public class AST2TemplateTests extends AST2TestBase {
 	public void testAmbiguityResolutionInNestedClassMethodBody_485388() throws Exception {
 		parseAndCheckBindings();
 	}
+	
+	//	template <typename...>
+	//	struct Voider {
+	//	  using type = void;
+	//	};
+	//
+	//	template <typename... Args>
+	//	using void_t = typename Voider<Args...>::type;
+	//
+	//	template <typename, template <typename...> class Op, typename... Args>
+	//	struct IsDetectedImpl;
+	//
+	//	template <template <typename...> class Op, typename... Args>
+	//	struct IsDetectedImpl<void_t<Op<Args...>>, Op, Args...> {};
+	public void testAmbiguityResolution_515453() throws Exception {
+		parseAndCheckBindings();
+	}
 
 	//	template<typename T, T v>
 	//	struct F {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTranslationUnit.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTranslationUnit.java
index 5e7c40235a1..8f01e8ba5a2 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTranslationUnit.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPASTTranslationUnit.java
@@ -16,6 +16,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 import org.eclipse.cdt.core.dom.ILinkage;
+import org.eclipse.cdt.core.dom.ast.ASTVisitor;
 import org.eclipse.cdt.core.dom.ast.IASTName;
 import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IASTTypeId;
@@ -23,6 +24,7 @@ import org.eclipse.cdt.core.dom.ast.IBasicType;
 import org.eclipse.cdt.core.dom.ast.IBasicType.Kind;
 import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.IMacroBinding;
+import org.eclipse.cdt.core.dom.ast.IProblemBinding;
 import org.eclipse.cdt.core.dom.ast.IScope;
 import org.eclipse.cdt.core.dom.ast.IType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTTranslationUnit;
@@ -204,10 +206,27 @@ public class CPPASTTranslationUnit extends ASTTranslationUnit implements ICPPAST
 		fScopeMapper.handleAdditionalDirectives(scope);
 	}
 
+	private class ProblemBindingClearer extends ASTVisitor {
+		public ProblemBindingClearer() {
+			shouldVisitNames = true;
+		}
+		@Override
+		public int visit(IASTName name) {
+			if (name.getBinding() instanceof IProblemBinding) {
+				name.setBinding(null);
+			}
+			return PROCESS_CONTINUE;
+		}
+	}
+	
 	@Override
 	public void resolveAmbiguities() {
 		fAmbiguityResolver = new CPPASTAmbiguityResolver();
 		accept(fAmbiguityResolver);
+		// During ambiguity resolution, names can incorrectly get stuck with ProblemBindings.
+		// To prevent this, clear all ProblemBindings here, allowing name resolution for
+		// the affected names to be attempted again with a fully ambiguity-resolved AST.
+		accept(new ProblemBindingClearer());
 		fAmbiguityResolver = null;
 	}