[PATCH] D131465: C++/ObjC++: switch to gnu++17 as the default standard

[Fangrui Song via Phabricator via cfe-commits]

MaskRay updated this revision to Diff 458556.
MaskRay edited the summary of this revision.
MaskRay added a comment.

revert a clangd change after sammccall's change to make it immune to gnu++14/gnu++17 default change.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D131465/new/

https://reviews.llvm.org/D131465

Files:
  clang/docs/ReleaseNotes.rst
  clang/lib/Basic/LangStandards.cpp
  clang/test/Preprocessor/lang-std.cpp
  clang/test/Preprocessor/lang-std.cu
  clang/test/lit.cfg.py
  clang/test/lit.site.cfg.py.in


Index: clang/test/lit.site.cfg.py.in
===================================================================
--- clang/test/lit.site.cfg.py.in
+++ clang/test/lit.site.cfg.py.in
@@ -24,6 +24,7 @@
 config.clang_arcmt = @CLANG_ENABLE_ARCMT@
 config.clang_default_pie_on_linux = @CLANG_DEFAULT_PIE_ON_LINUX@
 config.clang_enable_opaque_pointers = @CLANG_ENABLE_OPAQUE_POINTERS_INTERNAL@
+config.clang_default_std_cxx = "@CLANG_DEFAULT_STD_CXX@"
 config.clang_default_cxx_stdlib = "@CLANG_DEFAULT_CXX_STDLIB@"
 config.clang_staticanalyzer = @CLANG_ENABLE_STATIC_ANALYZER@
 config.clang_staticanalyzer_z3 = @LLVM_WITH_Z3@
Index: clang/test/lit.cfg.py
===================================================================
--- clang/test/lit.cfg.py
+++ clang/test/lit.cfg.py
@@ -131,6 +131,9 @@
 if config.clang_enable_opaque_pointers:
     config.available_features.add('enable-opaque-pointers')
 
+if config.clang_default_std_cxx != '':
+    config.available_features.add('default-std-cxx')
+
 # Set available features we allow tests to conditionalize on.
 #
 if config.clang_default_cxx_stdlib != '':
Index: clang/test/Preprocessor/lang-std.cu
===================================================================
--- clang/test/Preprocessor/lang-std.cu
+++ /dev/null
@@ -1,7 +0,0 @@
-// RUN: %clang_cc1 -dM -E -x hip %s | FileCheck -check-prefix=CXX14 %s
-// RUN: %clang_cc1 -dM -E %s | FileCheck -check-prefix=CXX14 %s
-// RUN: %clang_cc1 -dM -E -std=c++98 -x hip %s | FileCheck -check-prefix=CXX98 %s
-// RUN: %clang_cc1 -dM -E -std=c++98 %s | FileCheck -check-prefix=CXX98 %s
-
-// CXX98: #define __cplusplus 199711L
-// CXX14: #define __cplusplus 201402L
Index: clang/test/Preprocessor/lang-std.cpp
===================================================================
--- /dev/null
+++ clang/test/Preprocessor/lang-std.cpp
@@ -0,0 +1,14 @@
+// UNSUPPORTED: default-std-cxx, ps4, ps5
+/// Test default standards when CLANG_DEFAULT_STD_CXX is unspecified.
+/// PS4/PS5 default to gnu++14.
+
+// RUN: %clang_cc1 -dM -E %s | FileCheck --check-prefix=CXX17 %s
+// RUN: %clang_cc1 -dM -E -x cuda %s | FileCheck --check-prefix=CXX14 %s
+// RUN: %clang_cc1 -dM -E -x hip %s | FileCheck --check-prefix=CXX14 %s
+
+// RUN: %clang_cc1 -dM -E -x cuda -std=c++14 %s | FileCheck --check-prefix=CXX14 %s
+// RUN: %clang_cc1 -dM -E -x hip -std=c++98 %s | FileCheck --check-prefix=CXX98 %s
+
+// CXX98: #define __cplusplus 199711L
+// CXX14: #define __cplusplus 201402L
+// CXX17: #define __cplusplus 201703L
Index: clang/lib/Basic/LangStandards.cpp
===================================================================
--- clang/lib/Basic/LangStandards.cpp
+++ clang/lib/Basic/LangStandards.cpp
@@ -75,10 +75,9 @@
     if (CLANG_DEFAULT_STD_CXX != LangStandard::lang_unspecified)
       return CLANG_DEFAULT_STD_CXX;
 
-    if (T.isDriverKit())
-      return LangStandard::lang_gnucxx17;
-    else
+    if (T.isPS())
       return LangStandard::lang_gnucxx14;
+    return LangStandard::lang_gnucxx17;
   case Language::RenderScript:
     return LangStandard::lang_c99;
   case Language::HIP:
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -200,6 +200,10 @@
 
 - Implemented DR692, DR1395 and DR1432. Use the ``-fclang-abi-compat=15`` option
   to get the old partial ordering behavior regarding packs.
+* Clang's default C++ dialect is now ``gnu++17`` instead of ``gnu++14``. This
+  means Clang will by default accept code using features from C++17 and
+  conforming GNU extensions. Projects incompatible with C++17 can add
+  ``-std=gnu++14`` to their build settings to restore the previous behaviour.
 
 C++20 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^


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