fix: __attribute__ of declarator is missing from AST (issues #706 and #602)

Move `mark()` call to before `__attribute_decl_seq()` in
`GNUCSourceParser.consumePointerOperators()` so that when no pointer
operator follows an attribute, `backup(mark)` correctly restores the
token stream to before the attribute. Previously, the mark was set
*after* consuming the attribute, so the attribute was permanently lost.

Also update `startOffset` to use `last.getOffset()` (the offset of the
`*` token) instead of `mark.getOffset()` to preserve correct pointer
operator location information.

Agent-Logs-Url: https://github.com/emmtrix/cdt/sessions/64cb901c-b4db-40ca-bc5e-49f7c8ae83a2

Co-authored-by: strimo378 <59825937+strimo378@users.noreply.github.com>

Author: Copilot

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2CPPAttributeTests.java

@@ -642,4 +642,19 @@ public void testMixedAttributeSpecifiers() throws Exception {
 		assertSame(parent1, parent3);
 		assertSame(parent1, parent4);
 	}
+
+	//	int target;
+	//	extern int other, __attribute__((alias("target"))) error_decl;
+	@Test
+	public void testGCCAttributeBeforeDeclaratorInList_bug706() throws Exception {
+		IASTTranslationUnit tu = parseAndCheckBindings(getAboveComment(), ParserLanguage.C, ScannerKind.GNU);
+		checkAttributeRelations(getAttributeSpecifiers(tu), IASTDeclarator.class);
+	}
+
+	//	extern int ( __attribute__((__artificial__)) func)();
+	@Test
+	public void testGCCAttributeInNestedDeclarator_bug602() throws Exception {
+		IASTTranslationUnit tu = parseAndCheckBindings(getAboveComment(), ParserLanguage.C, ScannerKind.GNU);
+		checkAttributeRelations(getAttributeSpecifiers(tu), IASTDeclarator.class);
+	}
 }

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

@@ -869,10 +869,11 @@ protected IASTTypeId typeId(DeclarationOptions option) throws EndOfFileException
 	protected void consumePointerOperators(List<IASTPointerOperator> pointerOps)
 			throws EndOfFileException, BacktrackException {
 		for (;;) {
+			IToken mark = mark();
+
 			// __attribute__ in-between pointers
 			__attribute_decl_seq(supportAttributeSpecifiers, false);
 
-			IToken mark = mark();
 			IToken last = null;
 
 			boolean isConst = false, isVolatile = false, isRestrict = false;
@@ -883,7 +884,7 @@ protected void consumePointerOperators(List<IASTPointerOperator> pointerOps)
 			}
 
 			last = consume();
-			int startOffset = mark.getOffset();
+			int startOffset = last.getOffset();
 			for (;;) {
 				IToken t = LA(1);
 				switch (LT(1)) {