Update diagnostic groups for pre-compat warnings

[aaron.ballman]

Summary

As a follow-up to D95691, add new diagnostic groups named pre-c++N-compat to replace the old diagnostic groups with the standards listed out explicitly. The old group names are retained for backwards compatibility.

[aaron.ballman]

Ping

[aaron.ballman]

I feel comfortable accepting this one on my own authority given that it follows the pattern we talked about, so I'm accepting the review (so I can close it) and I've committed in ecfa87453113dad6bd9430606a06f7ab728cc21b. If there are concerns, I'll happily address them post commit.

[aaron.ballman]

Committed in ecfa87453113dad6bd9430606a06f7ab728cc21b

clang/include/clang/Basic/DiagnosticGroups.td

 
 def InvalidIOSDeploymentTarget : DiagGroup<"invalid-ios-deployment-target">;
 
 def CXX17CompatMangling : DiagGroup<"c++17-compat-mangling">;
 def : DiagGroup<"c++1z-compat-mangling", [CXX17CompatMangling]>;
 // Name of this warning in GCC.
 def NoexceptType : DiagGroup<"noexcept-type", [CXX17CompatMangling]>;
 
-// Warnings for C2x code which is not compatible with prior C standards.
+// Warnings for C code which is not compatible with previous C standards.
 def CPre2xCompat : DiagGroup<"pre-c2x-compat">;
 def CPre2xCompatPedantic : DiagGroup<"pre-c2x-compat-pedantic",
                                      [CPre2xCompat]>;
 
-// Warnings for C++1y code which is not compatible with prior C++ standards.
-def CXXPre14Compat : DiagGroup<"c++98-c++11-compat">;
-def CXXPre14CompatPedantic : DiagGroup<"c++98-c++11-compat-pedantic",
+// Warnings for C++ code which is not compatible with previous C++ standards.
+def CXXPre14Compat : DiagGroup<"pre-c++14-compat">;
+def : DiagGroup<"c++98-c++11-compat", [CXXPre14Compat]>;
+def CXXPre14CompatPedantic : DiagGroup<"pre-c++14-compat-pedantic",
                                        [CXXPre14Compat,
                                         CXXPre14CompatBinaryLiteral]>;
-def CXXPre17Compat : DiagGroup<"c++98-c++11-c++14-compat">;
-def CXXPre17CompatPedantic : DiagGroup<"c++98-c++11-c++14-compat-pedantic",
+def : DiagGroup<"c++98-c++11-compat-pedantic", [CXXPre14CompatPedantic]>;
+def CXXPre17Compat : DiagGroup<"pre-c++17-compat">;
+def : DiagGroup<"c++98-c++11-c++14-compat", [CXXPre17Compat]>;
+def CXXPre17CompatPedantic : DiagGroup<"pre-c++17-compat-pedantic",
                                        [CXXPre17Compat]>;
-def CXXPre20Compat : DiagGroup<"c++98-c++11-c++14-c++17-compat">;
-def CXXPre20CompatPedantic : DiagGroup<"c++98-c++11-c++14-c++17-compat-pedantic",
+def : DiagGroup<"c++98-c++11-c++14-compat-pedantic",
+                [CXXPre17CompatPedantic]>;
+def CXXPre20Compat : DiagGroup<"pre-c++20-compat">;
+def : DiagGroup<"c++98-c++11-c++14-c++17-compat", [CXXPre20Compat]>;
+def CXXPre20CompatPedantic : DiagGroup<"pre-c++20-compat-pedantic",
                                        [CXXPre20Compat]>;
+def : DiagGroup<"c++98-c++11-c++14-c++17-compat-pedantic",
+                [CXXPre20CompatPedantic]>;
 def CXXPre2bCompat : DiagGroup<"pre-c++2b-compat">;
 def CXXPre2bCompatPedantic :
   DiagGroup<"pre-c++2b-compat-pedantic", [CXXPre2bCompat]>;
 
 def CXX98CompatBindToTemporaryCopy :
   DiagGroup<"c++98-compat-bind-to-temporary-copy">;
 def CXX98CompatLocalTypeTemplateArgs :
   DiagGroup<"c++98-compat-local-type-template-args">;

clang/test/Parser/static_assert.c

 // RUN: %clang_cc1 -fsyntax-only -std=c2x -DTEST_SPELLING -verify=c2x %s
 // RUN: %clang_cc1 -fsyntax-only -std=c2x -DTEST_SPELLING -fms-compatibility -verify=c2x-ms %s
 // RUN: %clang_cc1 -fsyntax-only -std=c2x -Wpre-c2x-compat -verify=c2x-compat %s
 // RUN: %clang_cc1 -fsyntax-only -std=c99 -verify=c99 %s
 // RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic -verify=c99-pedantic %s
 // RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify=cxx17 -x c++ %s
 // RUN: %clang_cc1 -fsyntax-only -std=c++17 -pedantic -verify=cxx17-pedantic -x c++ %s
 // RUN: %clang_cc1 -fsyntax-only -std=c++98 -verify=cxx98 -x c++ %s
 // RUN: %clang_cc1 -fsyntax-only -std=c++98 -pedantic -verify=cxx98-pedantic -x c++ %s
-// RUN: %clang_cc1 -fsyntax-only -std=c++17 -Wc++98-c++11-c++14-compat -verify=cxx17-compat -x c++ %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -Wpre-c++17-compat -verify=cxx17-compat -x c++ %s
 
 // cxx17-no-diagnostics
 
 #ifdef TEST_SPELLING
 // Only test the C++ spelling in C mode in some of the tests, to reduce the
 // amount of diagnostics to have to check. This spelling is allowed in MS-
 // compatibility mode in C, but otherwise produces errors.
 static_assert(1, ""); // c2x-error {{expected parameter declarator}} \

clang/test/SemaCXX/cxx98-compat-pedantic.cpp

 // RUN: %clang_cc1 -fsyntax-only -std=c++1y -DCXX1Y -Wc++98-compat-pedantic -verify %s -DCXX1Y2
 // RUN: %clang_cc1 -fsyntax-only -std=c++1y -DCXX1Y -Wc++98-compat -Werror %s -DCXX1Y2
 // RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wc++98-compat-pedantic -verify %s
 // RUN: %clang_cc1 -fsyntax-only -std=c++11 -Wc++98-compat -Werror %s
 // RUN: %clang_cc1 -fsyntax-only -std=c++98 -Werror %s -DCXX98
 
-// RUN: %clang_cc1 -fsyntax-only -std=c++1y -Wc++98-compat-pedantic -verify %s -Wno-c++98-c++11-compat-pedantic -DCXX1Y2
+// RUN: %clang_cc1 -fsyntax-only -std=c++1y -Wc++98-compat-pedantic -verify %s -Wno-pre-c++14-compat-pedantic -DCXX1Y2
 
 // -Wc++98-compat-pedantic warns on C++11 features which we accept without a
 // warning in C++98 mode.
 
 #line 32767 // ok
 #line 32768 // expected-warning {{#line number greater than 32767 is incompatible with C++98}}
 
 #define VA_MACRO(x, ...) x // expected-warning {{variadic macros are incompatible with C++98}}

clang/test/SemaCXX/inline.cpp

 // RUN: %clang_cc1 -fsyntax-only -verify %s
 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++14 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s -Wc++98-c++11-c++14-compat
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s -Wpre-c++17-compat
 
 // Check that we don't allow illegal uses of inline
 // (checking C++-only constructs here)
 struct c {inline int a;}; // expected-error{{'inline' can only appear on functions}}
 
 void localVar() {
   inline int a; // expected-error{{inline declaration of 'a' not allowed in block scope}}
 }
 
 // Check that we warn appropriately.
 #if __cplusplus <= 201402L
 inline int a; // expected-warning{{inline variables are a C++17 extension}}
 #else
 inline int a; // expected-warning{{inline variables are incompatible with C++ standards before C++17}}
 #endif