[clang] fixing -ast-print for variadic parameter pack in lambda capture

[Tyker]

Summary

currently for:

 template<typename ... T>
void f(T... t) {
  auto l = [t...]{};
}

clang -ast-print file.cpp
outputs:

template <typename ...T> void f(T ...t) {
    auto l = [t]         {
        }
;
}

notice that there is not ... in the capture list of the lambda. this patch fixes this issue. and add test for it.

[Tyker]

could you commit it for me please ?

[Rakete1111]

You might want to consider getting commit access.

lib/AST/StmtPrinter.cpp

for (LambdaExpr::capture_iterator C = Node->explicit_capture_begin(),
     case LCK_ByCopy:
       OS << C->getCapturedVar()->getName();
       break;
 
     case LCK_VLAType:
       llvm_unreachable("VLA type in explicit captures.");
     }
 
+    if (C->isPackExpansion())
+      OS << "...";
+
     if (Node->isInitCapture(C))
       PrintExpr(C->getCapturedVar()->getInit());
   }
   OS << ']';
 
   if (!Node->getExplicitTemplateParameters().empty()) {
     Node->getTemplateParameterList()->print(
         OS, Node->getLambdaClass()->getASTContext(),

test/AST/ast-printer-lambda.cpp

+// RUN: %clang_cc1 -ast-print -std=c++17 %s | FileCheck %s
+
+struct S {
+template<typename ... T>
+void test1(int i, T... t) {
+{
+  auto lambda = [i]{};
+  //CHECK: [i] {
+}
+{
+  auto lambda = [=]{};
+  //CHECK: [=] {
+}
+{
+  auto lambda = [&]{};
+  //CHECK: [&] {
+}
+{
+  auto lambda = [t..., i]{};
+  //CHECK: [t..., i] {
+}
+{
+  auto lambda = [&t...]{};
+  //CHECK: [&t...] {
+}
+{
+  auto lambda = [this, &t...]{};
+  //CHECK: [this, &t...] {
+}
+{
+  auto lambda = [t..., this]{};
+  //CHECK: [t..., this] {
+}
+}
+
+};
 No newline at end of file