| // RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++14 | 
 | // RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++17 | 
 | // RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++20 -Wc++17-compat | 
 |  | 
 | namespace inline foo1::foo2::foo3 { // expected-error {{expected identifier or '{'}} expected-error {{use of undeclared identifier 'foo1'}} | 
 | } | 
 |  | 
 | inline namespace foo4::foo5::foo6 { // expected-error {{nested namespace definition cannot be 'inline'}}} | 
 | } | 
 |  | 
 | #if __cplusplus <= 201402L | 
 | // expected-warning@+7 {{nested namespace definition is a C++17 extension; define each namespace separately}} | 
 | // expected-warning@+6 {{inline nested namespace definition is a C++20 extension}} | 
 | #elif __cplusplus <= 201703L | 
 | // expected-warning@+4 {{inline nested namespace definition is a C++20 extension}} | 
 | #else | 
 | // expected-warning@+2 {{inline nested namespace definition is incompatible with C++ standards before C++20}} | 
 | #endif | 
 | namespace valid1::valid2::inline valid3::inline valid4::valid5 {} | 
 | // expected-note@-1 4 {{previous definition is here}} | 
 |  | 
 | #if __cplusplus <= 201402L | 
 | // expected-warning@+3 {{nested namespace definition is a C++17 extension; define each namespace separately}} | 
 | #endif | 
 | //expected-warning@+1 2 {{inline namespace reopened as a non-inline namespace}} | 
 | namespace valid1::valid2::valid3::valid4::valid5 {} | 
 |  | 
 | #if __cplusplus <= 201402L | 
 | // expected-warning@+7 {{nested namespace definition is a C++17 extension; define each namespace separately}} | 
 | // expected-warning@+6 {{inline nested namespace definition is a C++20 extension}} | 
 | #elif __cplusplus <= 201703L | 
 | // expected-warning@+4 {{inline nested namespace definition is a C++20 extension}} | 
 | #else | 
 | // expected-warning@+2 {{inline nested namespace definition is incompatible with C++ standards before C++20}} | 
 | #endif | 
 | namespace valid1::valid2::inline valid3::inline valid4::valid5 {} | 
 |  | 
 | namespace valid1 { | 
 | namespace valid2 { | 
 | //expected-warning@+1 {{inline namespace reopened as a non-inline namespace}} | 
 | namespace valid3 { | 
 | //expected-warning@+1 {{inline namespace reopened as a non-inline namespace}} | 
 | namespace valid4 { | 
 | namespace valid5 { | 
 | } | 
 | } // namespace valid4 | 
 | } // namespace valid3 | 
 | } // namespace valid2 | 
 | } // namespace valid1 | 
 |  |