Bug 553794 - Add support for the __integer_pack builtin

Change-Id: Idc978d1d0b44cfe326283a0c3779969fdc3f3599

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java

@@ -11385,4 +11385,19 @@ public class AST2TemplateTests extends AST2CPPTestBase {
 	public void testStringLiteralOperatorTemplate_536986() throws Exception {
 		parseAndCheckImplicitNameBindings();
 	}
+
+	//	template <int...>
+	//	struct integer_sequence {};
+	//
+	//	template <int N>
+	//	using make_integer_sequence = integer_sequence<__integer_pack(N)...>;
+	//
+	//	using type1 = integer_sequence<0, 1, 2>;
+	//	using type2 = make_integer_sequence<3>;
+	public void testIntegerPack_553794() throws Exception {
+		BindingAssertionHelper helper = getAssertionHelper();
+		ITypedef type1 = helper.assertNonProblem("type1");
+		ITypedef type2 = helper.assertNonProblem("type2");
+		assertSameType(type1, type2);
+	}
 }

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/IASTUnaryExpression.java

@@ -134,6 +134,12 @@ public interface IASTUnaryExpression extends IASTExpression {
 	 */
 	public static final int op_labelReference = 18;
 
+	/**
+	 * For GCC parsers in C++ mode, only: '__integer_pack ( expression )'
+	 * @since 6.10
+	 */
+	public static final int op_integerPack = 19;
+
 	/**
 	 * {@code OPERAND} represents the relationship between an {@code IASTUnaryExpression} and
 	 * it's nested {@code IASTExpression}.

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/parser/cpp/GPPScannerExtensionConfiguration.java

@@ -175,6 +175,7 @@ public class GPPScannerExtensionConfiguration extends GNUScannerExtensionConfigu
 			}
 			if (version >= VERSION_8_0) {
 				addKeyword(GCCKeywords.cp__is_constructible, IGCCToken.tTT_is_constructible);
+				addKeyword(GCCKeywords.cp__integer_pack, IGCCToken.tTT_integer_pack);
 			}
 		} else if (compiler == CompilerType.Clang) {
 			// As documented at
@@ -201,6 +202,7 @@ public class GPPScannerExtensionConfiguration extends GNUScannerExtensionConfigu
 			addKeyword(GCCKeywords.cp__is_trivially_constructible, IGCCToken.tTT_is_trivially_constructible);
 			addKeyword(GCCKeywords.cp__is_trivially_assignable, IGCCToken.tTT_is_trivially_assignable);
 			addKeyword(GCCKeywords.cp__is_constructible, IGCCToken.tTT_is_constructible);
+			addKeyword(GCCKeywords.cp__integer_pack, IGCCToken.tTT_integer_pack);
 		} else if (compiler == CompilerType.MSVC) {
 			// As documented at
 			// https://docs.microsoft.com/en-us/cpp/extensions/compiler-support-for-type-traits-cpp-component-extensions?view=vs-2017

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/GCCKeywords.java

@@ -90,4 +90,7 @@ public class GCCKeywords {
 
 	/** @since 6.6 */
 	public static final char[] cp__is_constructible = "__is_constructible".toCharArray();
+
+	/** @since 6.10 */
+	public static final char[] cp__integer_pack = "__integer_pack".toCharArray();
 }

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/parser/IGCCToken.java

@@ -93,4 +93,7 @@ public interface IGCCToken extends IToken {
 
 	/** @since 6.6 */
 	int tTT_is_constructible = FIRST_RESERVED_IGCCToken + 35;
+
+	/** @since 6.10 */
+	int tTT_integer_pack = FIRST_RESERVED_IGCCToken + 36;
 }

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/GNUCPPSourceParser.java

@@ -1540,7 +1540,8 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
 		case IGCCToken.t___alignof__:
 			return parseTypeidInParenthesisOrUnaryExpression(false, consume().getOffset(),
 					IASTTypeIdExpression.op_alignof, IASTUnaryExpression.op_alignOf, ctx, strat);
-
+		case IGCCToken.tTT_integer_pack:
+			return unaryExpression(IASTUnaryExpression.op_integerPack, ctx, strat);
 		case IGCCToken.tTT_has_nothrow_assign:
 		case IGCCToken.tTT_has_nothrow_constructor:
 		case IGCCToken.tTT_has_nothrow_copy:

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalUnary.java

@@ -19,6 +19,7 @@ import static org.eclipse.cdt.core.dom.ast.IASTExpression.ValueCategory.PRVALUE;
 import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_alignOf;
 import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_amper;
 import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_bracketedPrimary;
+import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_integerPack;
 import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_minus;
 import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_noexcept;
 import static org.eclipse.cdt.core.dom.ast.IASTUnaryExpression.op_not;
@@ -156,6 +157,8 @@ public class EvalUnary extends CPPDependentEvaluation {
 			return fArgument.referencesTemplateParameter();
 		case op_throw:
 			return false;
+		case op_integerPack:
+			return true;
 		default:
 			return fArgument.isValueDependent();
 		}
@@ -242,6 +245,8 @@ public class EvalUnary extends CPPDependentEvaluation {
 			return CPPVisitor.get_type_info();
 		case op_throw:
 			return CPPSemantics.VOID_TYPE;
+		case op_integerPack:
+			return fArgument.getType();
 		case op_amper:
 			if (fAddressOfQualifiedNameBinding instanceof ICPPMember) {
 				ICPPMember member = (ICPPMember) fAddressOfQualifiedNameBinding;
@@ -394,6 +399,10 @@ public class EvalUnary extends CPPDependentEvaluation {
 
 	@Override
 	public ICPPEvaluation instantiate(InstantiationContext context, int maxDepth) {
+		if (fOperator == op_integerPack && context.getPackOffset() != -1) {
+			return new EvalFixed(getType(), ValueCategory.PRVALUE, IntegralValue.create(context.getPackOffset()));
+		}
+
 		ICPPEvaluation argument = fArgument.instantiate(context, maxDepth);
 		IBinding binding = fAddressOfQualifiedNameBinding;
 		if (binding instanceof ICPPUnknownBinding) {
@@ -520,6 +529,15 @@ public class EvalUnary extends CPPDependentEvaluation {
 
 	@Override
 	public int determinePackSize(ICPPTemplateParameterMap tpMap) {
+		if (fOperator == op_integerPack) {
+			ICPPEvaluation instantiatedArg = fArgument.instantiate(new InstantiationContext(tpMap),
+					IntegralValue.MAX_RECURSION_DEPTH);
+			IValue value = instantiatedArg.getValue();
+			if (value.numberValue() != null) {
+				return (int) value.numberValue().longValue();
+			}
+			return CPPTemplates.PACK_SIZE_DEFER;
+		}
 		return fArgument.determinePackSize(tpMap);
 	}
 

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java

@@ -2322,6 +2322,9 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 			addTypeTraitPrimitive("is_trivially_copyable", GCCKeywords.cp__is_trivially_copyable);
 			addTypeTraitPrimitive("is_union", GCCKeywords.cp__is_union);
 			addTypeTraitPrimitive("underlying_type", GCCKeywords.cp__underlying_type);
+
+			// TODO: If at some point we add support for __has_builtin, "__integer_pack"
+			//       should be added to the list of supported builtins.
 		}
 		return sSupportedFeatures;
 	}