Add -std=c++17

[hans]

Summary

As suggested on PR33912.

Trying to keep this small to make it easy to merge to the 5.0 branch. We can do a follow-up with more thorough renaming (diagnostic text, options, ids, etc.) later.

(For c++14 this was done in r215982, and I think a smaller patch for the 3.5 branch: http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20140818/113013.html)

[rsmith]

include/clang/Frontend/LangStandards.def

113

Missing "with amendments" compared to the other languages. We already implement some DRs against c++17.

[hans]

include/clang/Frontend/LangStandards.def

113

Thanks! I wasn't sure about that part.

include/clang/Frontend/LangStandards.def

 LANGSTANDARD_ALIAS_DEPR(cxx14, "c++1y")
 
 LANGSTANDARD(gnucxx14, "gnu++14",
              CXX, "ISO C++ 2014 with amendments and GNU extensions",
              LineComment | CPlusPlus | CPlusPlus11 | CPlusPlus14 | Digraphs |
              GNUMode)
 LANGSTANDARD_ALIAS_DEPR(gnucxx14, "gnu++1y")
 
-LANGSTANDARD(cxx1z, "c++1z",
-             CXX, "Working draft for ISO C++ 2017",
+LANGSTANDARD(cxx17, "c++17",
+             CXX, "ISO C++ 2017",
              LineComment | CPlusPlus | CPlusPlus11 | CPlusPlus14 | CPlusPlus1z |
              Digraphs | HexFloat)
+LANGSTANDARD_ALIAS_DEPR(cxx17, "c++1z")
 
-LANGSTANDARD(gnucxx1z, "gnu++1z",
-             CXX, "Working draft for ISO C++ 2017 with GNU extensions",
+LANGSTANDARD(gnucxx17, "gnu++17",
+             CXX, "ISO C++ 2017 with GNU extensions",
              LineComment | CPlusPlus | CPlusPlus11 | CPlusPlus14 | CPlusPlus1z |
              Digraphs | HexFloat | GNUMode)
+LANGSTANDARD_ALIAS_DEPR(gnucxx17, "gnu++1z")
 
 LANGSTANDARD(cxx2a, "c++2a",
              CXX, "Working draft for ISO C++ 2020",
              LineComment | CPlusPlus | CPlusPlus11 | CPlusPlus14 | CPlusPlus1z |
              CPlusPlus2a | Digraphs | HexFloat)
 
 LANGSTANDARD(gnucxx2a, "gnu++2a",
              CXX, "Working draft for ISO C++ 2020 with GNU extensions",

test/Driver/unknown-std.cpp

 // This file checks output given when processing C++/ObjC++ files.
 // When user selects invalid language standard
 // print out supported values with short description.
 
 // RUN: not %clang %s -std=foobar -c 2>&1 | FileCheck --match-full-lines %s
 // RUN: not %clang -x objective-c++ %s -std=foobar -c 2>&1 | FileCheck --match-full-lines %s
 // RUN: not %clang -x cuda -nocudainc -nocudalib %s -std=foobar -c 2>&1 | FileCheck --match-full-lines --check-prefix=CHECK --check-prefix=CUDA %s
 
 // CHECK: error: invalid value 'foobar' in '-std=foobar'
 // CHECK-NEXT: note: use 'c++98' or 'c++03' for 'ISO C++ 1998 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++98' or 'gnu++03' for 'ISO C++ 1998 with amendments and GNU extensions' standard
 // CHECK-NEXT: note: use 'c++11' for 'ISO C++ 2011 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++11' for 'ISO C++ 2011 with amendments and GNU extensions' standard
 // CHECK-NEXT: note: use 'c++14' for 'ISO C++ 2014 with amendments' standard
 // CHECK-NEXT: note: use 'gnu++14' for 'ISO C++ 2014 with amendments and GNU extensions' standard
-// CHECK-NEXT: note: use 'c++1z' for 'Working draft for ISO C++ 2017' standard
-// CHECK-NEXT: note: use 'gnu++1z' for 'Working draft for ISO C++ 2017 with GNU extensions' standard
+// CHECK-NEXT: note: use 'c++17' for 'ISO C++ 2017' standard
+// CHECK-NEXT: note: use 'gnu++17' for 'ISO C++ 2017 with GNU extensions' standard
 // CHECK-NEXT: note: use 'c++2a' for 'Working draft for ISO C++ 2020' standard
 // CHECK-NEXT: note: use 'gnu++2a' for 'Working draft for ISO C++ 2020 with GNU extensions' standard
 // CUDA-NEXT: note: use 'cuda' for 'NVIDIA CUDA(tm)' standard
 
 // Make sure that no other output is present.
 // CHECK-NOT: {{^.+$}}
 

test/SemaCXX/cxx1z-init-statement.cpp

 // RUN: %clang_cc1 -std=c++1z -verify %s
+// RUN: %clang_cc1 -std=c++17 -verify %s
 
 void testIf() {
   int x = 0;
   if (x; x) ++x;
   if (int t = 0; t) ++t; else --t;
 
   if (int x, y = 0; y) // expected-note 2 {{previous definition is here}}
     int x = 0; // expected-error {{redefinition of 'x'}}