Fix and Testcase for 195943, exponential complexity parsing expressions with consequtive left parenthesis.

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2Tests.java

@@ -3878,4 +3878,18 @@ public class AST2Tests extends AST2BaseTest {
 		parse( buffer.toString(), ParserLanguage.CPP, false, false, true ); 
 		parse( buffer.toString(), ParserLanguage.C, false, false, true ); 
 	}
+	
+	public void test195943() throws Exception {
+		final int depth= 100;
+		StringBuffer buffer = new StringBuffer();
+		buffer.append("#define M0 1\n");
+		for (int i = 1; i < depth; i++) {
+			buffer.append("#define M" + i + " (M" + (i-1) + "+1)\n");
+		}
+		buffer.append("int a= M" + (depth-1) + ";\n");
+		long time= System.currentTimeMillis();
+		parse(buffer.toString(), ParserLanguage.CPP); 
+		parse( buffer.toString(), ParserLanguage.C);
+		assertTrue(System.currentTimeMillis()-time < 1000);
+	}
 }

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/AbstractGNUSourceCodeParser.java

@@ -2406,6 +2406,47 @@ public abstract class AbstractGNUSourceCodeParser implements ISourceCodeParser {
 		return false;
 	}
 	
+	protected boolean canBeTypeSpecifier() throws EndOfFileException {
+		switch (LT(1)) {
+		// simple type specifiers:
+		case IToken.tIDENTIFIER:
+		case IToken.tCOLONCOLON:
+        case IToken.t_void:
+		case IToken.t_char:
+		case IToken.t_wchar_t:
+		case IToken.t_bool:
+		case IToken.t_short:
+        case IToken.t_int:
+        case IToken.t_long:
+        case IToken.t_float:
+        case IToken.t_double:
+        case IToken.t__Bool:
+        case IToken.t__Complex:
+        case IToken.t__Imaginary:
+        case IToken.t_signed:
+        case IToken.t_unsigned:
+
+        // class-specifier:
+        case IToken.t_class:
+        case IToken.t_struct:
+        case IToken.t_union:
+
+        // enum-specifier:
+        case IToken.t_enum:
+
+        // elaborated type specifier: (together with class, struct, union, enum
+        case IToken.t_typename:
+        	
+        // cq-qualifiers
+		case IToken.t_const:
+        case IToken.t_volatile:
+        case IToken.t_restrict:
+        	return true;
+		}
+
+		return false;
+	}
+	
 	/**
 	 * Creates the ast node for a comment.
 	 * @since 4.0

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/c/GNUCSourceParser.java

@@ -1265,6 +1265,9 @@ public class GNUCSourceParser extends AbstractGNUSourceCodeParser {
     }
 
     protected IASTTypeId typeId(boolean forNewExpression) throws EndOfFileException {
+    	if (!canBeTypeSpecifier()) {
+    		return null;
+    	}
         IToken mark = mark();
         int startingOffset = mark.getOffset();
         IASTDeclSpecifier declSpecifier = null;

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

@@ -963,6 +963,9 @@ public class GNUCPPSourceParser extends AbstractGNUSourceCodeParser {
      * @throws BacktrackException
      */
     protected IASTTypeId typeId(boolean forNewExpression) throws EndOfFileException {
+    	if (!canBeTypeSpecifier()) {
+    		return null;
+    	}
         IToken mark = mark();
         int startingOffset = mark.getOffset();
         IASTDeclSpecifier declSpecifier = null;