Bug 541474 - Disambiguate function with default argument

Take number of explicitly passed arguments into account.

Change-Id: If85f072d8b18f3fd1ca28f3c5688e864b0ffb4cd
Signed-off-by: Hannes Vogt <hannes@havogt.de>

4 files changed, 34 insertions, 18 deletions

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 d4e6b667c63..2299b6b5dc5 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
@@ -2733,7 +2733,7 @@ public class CPPSemantics {
 				potentialCosts.add(fnCost);
 				continue;
 			}
-			int cmp = fnCost.compareTo(tu, bestFnCost);
+			int cmp = fnCost.compareTo(tu, bestFnCost, data.getFunctionArgumentCount());
 			if (cmp < 0) {
 				bestFnCost = fnCost;
 				ambiguousFunctions = null;
@@ -2745,7 +2745,7 @@ public class CPPSemantics {
 		if (potentialCosts != null) {
 			for (FunctionCost fnCost : potentialCosts) {
 				if (!fnCost.mustBeWorse(bestFnCost) && fnCost.performUDC()) {
-					int cmp = fnCost.compareTo(tu, bestFnCost);
+					int cmp = fnCost.compareTo(tu, bestFnCost, data.getFunctionArgumentCount());
 					if (cmp < 0) {
 						bestFnCost = fnCost;
 						ambiguousFunctions = null;
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 a2b17c0e9fd..0c6e1954ffd 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
@@ -2502,9 +2502,19 @@ public class CPPTemplates {
 		return null;
 	}
 
-	// 14.5.6.2 Partial ordering of function templates
-	static int orderFunctionTemplates(ICPPFunctionTemplate f1, ICPPFunctionTemplate f2, TypeSelection mode)
-			throws DOMException {
+	/**
+	 * 14.5.6.2 Partial ordering of function templates
+	 *
+	 * @param f1
+	 * @param f2
+	 * @param mode
+	 * @param nExplicitArgs determines the number of parameters taken into consideration for ordering:
+	 *        for ordering in the context of a call, nExplicitArguments should be the number of arguments in the call
+	 *        for ordering in other contexts, nExplicitArguments should be Integer.MAX_VALUE to indicate
+	 *         that all parameters should be considered
+	 */
+	static int orderFunctionTemplates(ICPPFunctionTemplate f1, ICPPFunctionTemplate f2, TypeSelection mode,
+			int nExplicitArgs) throws DOMException {
 		if (f1 == f2)
 			return 0;
 		if (f1 == null)
@@ -2512,8 +2522,8 @@ public class CPPTemplates {
 		if (f2 == null)
 			return 1;
 
-		int s1 = compareSpecialization(f1, f2, mode);
-		int s2 = compareSpecialization(f2, f1, mode);
+		int s1 = compareSpecialization(f1, f2, mode, nExplicitArgs);
+		int s2 = compareSpecialization(f2, f1, mode, nExplicitArgs);
 
 		if (s1 == s2)
 			return 0;
@@ -2523,6 +2533,11 @@ public class CPPTemplates {
 		return 1;
 	}
 
+	static int orderFunctionTemplates(ICPPFunctionTemplate f1, ICPPFunctionTemplate f2, TypeSelection mode)
+			throws DOMException {
+		return orderFunctionTemplates(f1, f2, mode, Integer.MAX_VALUE);
+	}
+
 	private static ICPPFunction transferFunctionTemplate(ICPPFunctionTemplate f) throws DOMException {
 		final ICPPTemplateParameter[] tpars = f.getTemplateParameters();
 		final int argLen = tpars.length;
@@ -2559,13 +2574,14 @@ public class CPPTemplates {
 		return arg;
 	}
 
-	private static ICPPFunctionType getFunctionTypeIgnoringParametersWithDefaults(ICPPFunction function) {
+	private static ICPPFunctionType getFunctionTypeIgnoringParametersWithDefaults(ICPPFunction function,
+			int nExplicitArgs) {
 		ICPPParameter[] parameters = function.getParameters();
 		IType[] parameterTypes = new IType[parameters.length];
 		int i;
 		for (i = 0; i < parameters.length; ++i) {
 			ICPPParameter parameter = parameters[i];
-			if (!parameter.hasDefaultValue()) {
+			if (i < nExplicitArgs || !parameter.hasDefaultValue()) {
 				parameterTypes[i] = parameter.getType();
 			} else {
 				break;
@@ -2579,8 +2595,8 @@ public class CPPTemplates {
 				originalType.takesVarArgs());
 	}
 
-	private static int compareSpecialization(ICPPFunctionTemplate f1, ICPPFunctionTemplate f2, TypeSelection mode)
-			throws DOMException {
+	private static int compareSpecialization(ICPPFunctionTemplate f1, ICPPFunctionTemplate f2, TypeSelection mode,
+			int nExplicitArgs) throws DOMException {
 		ICPPFunction transF1 = transferFunctionTemplate(f1);
 		if (transF1 == null)
 			return -1;
@@ -2588,7 +2604,7 @@ public class CPPTemplates {
 		final ICPPFunctionType ft2 = f2.getType();
 		// Ignore parameters with default arguments in the transformed function template
 		// as per [temp.func.order] p5.
-		final ICPPFunctionType transFt1 = getFunctionTypeIgnoringParametersWithDefaults(transF1);
+		final ICPPFunctionType transFt1 = getFunctionTypeIgnoringParametersWithDefaults(transF1, nExplicitArgs);
 		IType[] pars;
 		IType[] args;
 		switch (mode) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java
index 707ff7bd7e0..14470e681b2 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java
@@ -269,7 +269,7 @@ public class Conversions {
 					// Make sure top-level cv-qualifiers are compared
 					udcCost.setReferenceBinding(ReferenceBinding.LVALUE_REF);
 					FunctionCost udcFuncCost = new FunctionCost(op, udcCost);
-					int cmp = udcFuncCost.compareTo(null, bestUdcCost);
+					int cmp = udcFuncCost.compareTo(null, bestUdcCost, 1);
 					if (cmp <= 0) {
 						Cost cost = isReferenceCompatible(cv1T1, getNestedType(t, TDEF | REF), false); // converted to target
 						if (cost != null) {
@@ -794,7 +794,7 @@ public class Conversions {
 					c1 = new FunctionCost(ctor, checkImplicitConversionSequence(ptype, source, valueCat,
 							UDCMode.FORBIDDEN, Context.ORDINARY));
 				}
-				int cmp = c1.compareTo(null, cost1);
+				int cmp = c1.compareTo(null, cost1, 1);
 				if (cmp <= 0) {
 					cost1 = c1;
 					cost2 = new Cost(t, t, Rank.IDENTITY);
@@ -826,7 +826,7 @@ public class Conversions {
 							// Make sure top-level cv-qualifiers are compared
 							udcCost.setReferenceBinding(ReferenceBinding.LVALUE_REF);
 							FunctionCost c1 = new FunctionCost(op, udcCost);
-							int cmp = c1.compareTo(null, cost1);
+							int cmp = c1.compareTo(null, cost1, 1);
 							if (cmp <= 0) {
 								cost1 = c1;
 								cost2 = new Cost(t, t, Rank.IDENTITY);
@@ -890,7 +890,7 @@ public class Conversions {
 							udcCost.setReferenceBinding(ReferenceBinding.LVALUE_REF);
 						}
 						FunctionCost c1 = new FunctionCost(op, udcCost);
-						int cmp = c1.compareTo(null, cost1);
+						int cmp = c1.compareTo(null, cost1, 1);
 						if (cmp <= 0) {
 							cost1 = c1;
 							cost2 = c2;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java
index a4833904dca..1044779f327 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java
@@ -140,7 +140,7 @@ class FunctionCost {
 	/**
 	 * Compares this function call cost to another one.
 	 */
-	public int compareTo(IASTTranslationUnit tu, FunctionCost other) throws DOMException {
+	public int compareTo(IASTTranslationUnit tu, FunctionCost other, int nArguments) throws DOMException {
 		if (other == null)
 			return -1;
 
@@ -180,7 +180,7 @@ class FunctionCost {
 				haveBetter = true;
 			} else if (isTemplate && otherIsTemplate) {
 				TypeSelection ts = SemanticUtil.isConversionOperator(f1) ? RETURN_TYPE : PARAMETERS;
-				int order = CPPTemplates.orderFunctionTemplates(otherAsTemplate, asTemplate, ts);
+				int order = CPPTemplates.orderFunctionTemplates(otherAsTemplate, asTemplate, ts, nArguments);
 				if (order < 0) {
 					haveBetter = true;
 				} else if (order > 0) {