[clang][modules] Add features for recent C++ versions

Add cplusplus20, cplusplus23, and cplusplus26 (but don't document
the latter, following the current policy).

Differential Revision: https://reviews.llvm.org/D150773

5 files changed, 29 insertions, 3 deletions

diff --git a/clang/docs/Modules.rst b/clang/docs/Modules.rst
index 825d8722c4d5..a54850f5457b 100644
--- a/clang/docs/Modules.rst
+++ b/clang/docs/Modules.rst
@@ -573,6 +573,12 @@ cplusplus14
 cplusplus17
   C++17 support is available.
 
+cplusplus20
+  C++20 support is available.
+
+cplusplus23
+  C++23 support is available.
+
 c99
   C99 support is available.
 
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2f13ef96ba03..0059707529e0 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -94,6 +94,7 @@ C++20 Feature Support
 - Clang now implements `[temp.deduct]p9`. Substitution failures inside lambdas from
   unevaluated contexts will be surfaced as errors. They were previously handled as
   SFINAE.
+- Clang now supports `requires cplusplus20` for module maps.
 
 C++23 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
@@ -108,6 +109,7 @@ C++23 Feature Support
   longer have to be constexpr compatible but rather support a less restricted requirements for constexpr
   functions. Which include allowing non-literal types as return values and parameters, allow calling of
   non-constexpr functions and constructors.
+- Clang now supports `requires cplusplus23` for module maps.
 
 C++2c Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
index e5994a7cc2fa..12ca19d8c6eb 100644
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -107,6 +107,9 @@ static bool hasFeature(StringRef Feature, const LangOptions &LangOpts,
                         .Case("cplusplus11", LangOpts.CPlusPlus11)
                         .Case("cplusplus14", LangOpts.CPlusPlus14)
                         .Case("cplusplus17", LangOpts.CPlusPlus17)
+                        .Case("cplusplus20", LangOpts.CPlusPlus20)
+                        .Case("cplusplus23", LangOpts.CPlusPlus23)
+                        .Case("cplusplus26", LangOpts.CPlusPlus26)
                         .Case("c99", LangOpts.C99)
                         .Case("c11", LangOpts.C11)
                         .Case("c17", LangOpts.C17)
diff --git a/clang/test/Modules/Inputs/DependsOnModule.framework/module.map b/clang/test/Modules/Inputs/DependsOnModule.framework/module.map
index 948a1efd743a..9cede40c45c3 100644
--- a/clang/test/Modules/Inputs/DependsOnModule.framework/module.map
+++ b/clang/test/Modules/Inputs/DependsOnModule.framework/module.map
@@ -46,6 +46,15 @@ framework module DependsOnModule {
   explicit module CXX17 {
     requires cplusplus17
   }
+  explicit module CXX20 {
+    requires cplusplus20
+  }
+  explicit module CXX23 {
+    requires cplusplus23
+  }
+  explicit module CXX26 {
+    requires cplusplus26
+  }
   explicit module C99 {
     requires c99
   }
diff --git a/clang/test/Modules/requires.m b/clang/test/Modules/requires.m
index 0ba51d4609ce..b370fa31ee0d 100644
--- a/clang/test/Modules/requires.m
+++ b/clang/test/Modules/requires.m
@@ -22,11 +22,17 @@
 @import DependsOnModule.CXX14; // expected-note {{module imported here}}
 // expected-error@DependsOnModule.framework/module.map:46 {{module 'DependsOnModule.CXX17' requires feature 'cplusplus17'}}
 @import DependsOnModule.CXX17; // expected-note {{module imported here}}
+// expected-error@DependsOnModule.framework/module.map:49 {{module 'DependsOnModule.CXX20' requires feature 'cplusplus20'}}
+@import DependsOnModule.CXX20; // expected-note {{module imported here}}
+// expected-error@DependsOnModule.framework/module.map:52 {{module 'DependsOnModule.CXX23' requires feature 'cplusplus23'}}
+@import DependsOnModule.CXX23; // expected-note {{module imported here}}
+// expected-error@DependsOnModule.framework/module.map:55 {{module 'DependsOnModule.CXX26' requires feature 'cplusplus26'}}
+@import DependsOnModule.CXX26; // expected-note {{module imported here}}
 #else
-// expected-error@DependsOnModule.framework/module.map:49 {{module 'DependsOnModule.C99' requires feature 'c99'}}
+// expected-error@DependsOnModule.framework/module.map:58 {{module 'DependsOnModule.C99' requires feature 'c99'}}
 @import DependsOnModule.C99; // expected-note {{module imported here}}
-// expected-error@DependsOnModule.framework/module.map:52 {{module 'DependsOnModule.C11' requires feature 'c11'}}
+// expected-error@DependsOnModule.framework/module.map:61 {{module 'DependsOnModule.C11' requires feature 'c11'}}
 @import DependsOnModule.C11; // expected-note {{module imported here}}
-// expected-error@DependsOnModule.framework/module.map:55 {{module 'DependsOnModule.C17' requires feature 'c17'}}
+// expected-error@DependsOnModule.framework/module.map:64 {{module 'DependsOnModule.C17' requires feature 'c17'}}
 @import DependsOnModule.C17; // expected-note {{module imported here}}
 #endif