Bug 516291 - If a function call has dependent arguments, resolve the function name as a CPPDeferredFunction even if there is only one viable candidate

This ensures that, when instantiating the function call, we get into
EvalFunctionSet.resolveFunction(), and check that the function is
actually callable with the instantiated argument types, and error out
if it isn't (which is important for SFINAE purposes).

Change-Id: Ia01755bc1a830fded1f61658f4beef875cc0b029

2 files changed, 19 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 f8147702a18..c0a010b010b 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
@@ -3916,8 +3916,7 @@ public class AST2TemplateTests extends AST2TestBase {
 		bh.assertNonProblem("f(b)", 1, ICPPUnknownBinding.class, IFunction.class);
 		bh.assertNonProblem("h(b)", 1, ICPPUnknownBinding.class, IFunction.class);
 		bh.assertNonProblem("m(b)", 1, ICPPUnknownBinding.class, IFunction.class);
-		IFunction g= bh.assertNonProblem("g(b)", 1);
-		assertFalse(g instanceof ICPPUnknownBinding);
+		bh.assertNonProblem("g(b)", 1, ICPPUnknownBinding.class, IFunction.class);
 	}
 
 	//    template<typename T> struct A  {
@@ -10112,6 +10111,24 @@ public class AST2TemplateTests extends AST2TestBase {
 		parseAndCheckBindings();
 	}
 	
+	//	class C {};
+	//
+	//	void aux(C);
+	//
+	//	template<typename T>
+	//	decltype(aux(T())) foo(T);
+	//
+	//	int foo(...);
+	//
+	//	void waldo(int);
+	//
+	//	int main() {
+	//	    waldo(foo(0));  // Error here
+	//	}
+	public void testSFINAEInDecltype_516291() throws Exception {
+		parseAndCheckBindings();
+	}
+	
 	//	template <typename, typename>
 	//	struct is_same {
 	//	    static constexpr bool value = false;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
index 157fe372339..ece87713b22 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
@@ -2616,8 +2616,6 @@ public class CPPSemantics {
 		// Check for dependent arguments
 		fns= tmp;
 		if (CPPTemplates.containsDependentType(argTypes)) {
-			if (viableCount == 1)
-				return fns[0];
 			setTargetedFunctionsToUnknown(argTypes);
 			return CPPDeferredFunction.createForCandidates(fns);
 		}