Test -Wpre-c++26-compat

Author: zyn0217

clang/test/SemaCXX/decomposed-condition.cpp

@@ -1,5 +1,7 @@
-// RUN: %clang_cc1 -std=c++1z -Wno-c++26-extensions -verify %s
-// RUN: %clang_cc1 -std=c++1z -Wno-c++26-extensions -verify %s -fexperimental-new-constant-interpreter
+// RUN: %clang_cc1 -std=c++17 -Wno-c++26-extensions -verify %s
+// RUN: %clang_cc1 -std=c++17 -Wno-c++26-extensions -verify %s -fexperimental-new-constant-interpreter
+// RUN: %clang_cc1 -std=c++2c -Wpre-c++26-compat -verify=cxx26,expected %s
+// RUN: %clang_cc1 -std=c++2c -Wpre-c++26-compat -verify=cxx26,expected %s -fexperimental-new-constant-interpreter
 
 struct X {
   bool flag;
@@ -14,7 +16,7 @@ struct X {
 
 namespace CondInIf {
 constexpr int f(X x) {
-  if (auto [ok, d] = x)
+  if (auto [ok, d] = x) // cxx26-warning {{structured binding declaration in a condition is incompatible with C++ standards before C++2c}}
     return d + int(ok);
   else
     return d * int(ok);
@@ -26,12 +28,13 @@ static_assert(f({true, 2}) == 3);
 static_assert(f({false, 2}) == 0);
 
 constexpr char g(char const (&x)[2]) {
-  if (auto &[a, b] = x)
+  if (auto &[a, b] = x) // cxx26-warning {{structured binding declaration in a condition is incompatible with C++ standards before C++2c}}
     return a;
   else
     return b;
 
-  if (auto [a, b] = x) // expected-error {{an array type is not allowed here}}
+  if (auto [a, b] = x) // expected-error {{an array type is not allowed here}} \
+                       // cxx26-warning {{structured binding declaration in a condition is incompatible with C++ standards before C++2c}}
     ;
 }
 
@@ -41,6 +44,7 @@ static_assert(g("x") == 'x');
 namespace CondInSwitch {
 constexpr int f(int n) {
   switch (X s = {true, n}; auto [ok, d] = s) {
+    // cxx26-warning@-1 {{structured binding declaration in a condition is incompatible with C++ standards before C++2c}}
     s = {};
   case 0:
     return int(ok);
@@ -65,6 +69,7 @@ namespace CondInWhile {
 constexpr int f(int n) {
   int m = 1;
   while (auto [ok, d] = X{n > 1, n}) {
+    // cxx26-warning@-1 {{structured binding declaration in a condition is incompatible with C++ standards before C++2c}}
     m *= d;
     --n;
   }
@@ -81,6 +86,7 @@ namespace CondInFor {
 constexpr int f(int n) {
   int a = 1, b = 1;
   for (X x = {true, n}; auto &[ok, d] = x; --d) {
+    // cxx26-warning@-1 {{structured binding declaration in a condition is incompatible with C++ standards before C++2c}}
     if (d < 2)
       ok = false;
     else {