4 files changed, 76 insertions, 0 deletions
diff --git a/clang/test/CodeGenCXX/char8_t.cpp b/clang/test/CodeGenCXX/char8_t.cpp
new file mode 100644
index 00000000000..e4dba584a6e
--- /dev/null
+++ b/clang/test/CodeGenCXX/char8_t.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -std=c++17 -emit-llvm -fchar8_t -triple x86_64-linux %s -o - | FileCheck %s
+
+// CHECK: define void @_Z1fDu(
+void f(char8_t c) {}
+
+// CHECK: define void @_Z1gIiEvDTplplcvT__ELA4_KDuELDu114EE
+template<typename T> void g(decltype(T() + u8"foo" + u8'r')) {}
+template void g<int>(const char8_t*);
diff --git a/clang/test/Lexer/char8_t.cpp b/clang/test/Lexer/char8_t.cpp
new file mode 100644
index 00000000000..20f820e2401
--- /dev/null
+++ b/clang/test/Lexer/char8_t.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s
+// RUN: %clang_cc1 -std=c++2a -verify %s -fchar8_t
+
+#if defined(__cpp_char8_t) && __is_identifier(char8_t)
+#error char8_t is an identifier under -fchar8_t
+#endif
+
+#if !defined(__cpp_char8_t) && !__is_identifier(char8_t)
+#error char8_t is a keyword under -fno-char8_t
+#endif
+
+char8_t c8t;
+#ifndef __cpp_char8_t
+// expected-error@-2 {{unknown type}}
+#else
+// expected-no-diagnostics
+#endif
diff --git a/clang/test/Lexer/cxx-features.cpp b/clang/test/Lexer/cxx-features.cpp
index a7d12e2e14f..352f08e73b3 100644
--- a/clang/test/Lexer/cxx-features.cpp
+++ b/clang/test/Lexer/cxx-features.cpp
@@ -6,6 +6,7 @@
 // RUN: %clang_cc1 -std=c++1z -fcxx-exceptions -fsized-deallocation -fconcepts-ts -DCONCEPTS_TS=1 -verify %s
 // RUN: %clang_cc1 -fno-rtti -fno-threadsafe-statics -verify %s -DNO_EXCEPTIONS -DNO_RTTI -DNO_THREADSAFE_STATICS -fsized-deallocation
 // RUN: %clang_cc1 -fcoroutines-ts -DNO_EXCEPTIONS -DCOROUTINES -verify -fsized-deallocation %s
+// RUN: %clang_cc1 -fchar8_t -DNO_EXCEPTIONS -DCHAR8_T -verify -fsized-deallocation %s
 
 // expected-no-diagnostics
 
@@ -242,3 +243,9 @@
 #if defined(COROUTINES) ? check(coroutines, 201703L, 201703L, 201703L, 201703L) : check(coroutines, 0, 0, 0, 0)
 #error "wrong value for __cpp_coroutines"
 #endif
+
+// --- not-yet-standard features --
+
+#if defined(CHAR8_T) ? check(char8_t, 201803, 201803, 201803, 201803) : check(char8_t, 0, 0, 0, 0)
+#error "wrong value for __cpp_char8_t"
+#endif
diff --git a/clang/test/SemaCXX/char8_t.cpp b/clang/test/SemaCXX/char8_t.cpp
new file mode 100644
index 00000000000..5eb3d7062d2
--- /dev/null
+++ b/clang/test/SemaCXX/char8_t.cpp
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -fchar8_t -std=c++2a -verify %s
+
+char8_t a = u8'a';
+char8_t b[] = u8"foo";
+char8_t c = 'a';
+char8_t d[] = "foo"; // expected-error {{initializing 'char8_t' array with plain string literal}} expected-note {{add 'u8' prefix}}
+
+char e = u8'a';
+char f[] = u8"foo"; // expected-error {{initialization of char array with UTF-8 string literal is not permitted by '-fchar8_t'}}
+char g = 'a';
+char h[] = "foo";
+
+void disambig() {
+  char8_t (a) = u8'x';
+}
+
+void operator""_a(char);
+void operator""_a(const char*, decltype(sizeof(0)));
+
+void test_udl1() {
+  int &x = u8'a'_a; // expected-error {{no matching literal operator}}
+  float &y = u8"a"_a; // expected-error {{no matching literal operator}}
+}
+
+int &operator""_a(char8_t);
+float &operator""_a(const char8_t*, decltype(sizeof(0)));
+
+void test_udl2() {
+  int &x = u8'a'_a;
+  float &y = u8"a"_a;
+}
+
+template<typename E, typename T> void check(T &&t) {
+  using Check = E;
+  using Check = T;
+}
+void check_deduction() {
+  check<char8_t>(u8'a');
+  check<const char8_t(&)[5]>(u8"a\u1000");
+}
+
+static_assert(sizeof(char8_t) == 1);
+static_assert(char8_t(-1) > 0);
+static_assert(u8"\u0080"[0] > 0);