[c++1z] Support constant folding for __builtin_strchr and __builtin_memchr.

llvm-svn: 286699

1 files changed, 39 insertions, 1 deletions

diff --git a/clang/test/SemaCXX/constexpr-string.cpp b/clang/test/SemaCXX/constexpr-string.cpp
index e614d43b30e..0ce3b05436e 100644
--- a/clang/test/SemaCXX/constexpr-string.cpp
+++ b/clang/test/SemaCXX/constexpr-string.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic
+// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic -fno-signed-char
 
 # 4 "/usr/include/string.h" 1 3 4
 extern "C" {
@@ -9,9 +10,12 @@ extern "C" {
   extern int strcmp(const char *s1, const char *s2);
   extern int strncmp(const char *s1, const char *s2, size_t n);
   extern int memcmp(const char *s1, const char *s2, size_t n); // expected-note {{here}}
+
+  extern char *strchr(const char *s, int c);
+  extern void *memchr(const void *s, int c, size_t n);
 }
 
-# 15 "SemaCXX/constexpr-string.cpp" 2
+# 19 "SemaCXX/constexpr-string.cpp" 2
 namespace Strlen {
   constexpr int n = __builtin_strlen("hello"); // ok
   constexpr int m = strlen("hello"); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strlen' cannot be used in a constant expression}}
@@ -66,3 +70,37 @@ namespace StrcmpEtc {
   constexpr int b = strncmp("hello", "world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strncmp' cannot be used in a constant expression}}
   constexpr int c = memcmp("hello", "world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'memcmp' cannot be used in a constant expression}}
 }
+
+namespace StrchrEtc {
+  constexpr const char *kStr = "abca\xff\0d";
+  constexpr char kFoo[] = {'f', 'o', 'o'};
+  static_assert(__builtin_strchr(kStr, 'a') == kStr);
+  static_assert(__builtin_strchr(kStr, 'b') == kStr + 1);
+  static_assert(__builtin_strchr(kStr, 'c') == kStr + 2);
+  static_assert(__builtin_strchr(kStr, 'd') == nullptr);
+  static_assert(__builtin_strchr(kStr, 'e') == nullptr);
+  static_assert(__builtin_strchr(kStr, '\0') == kStr + 5);
+  static_assert(__builtin_strchr(kStr, 'a' + 256) == nullptr);
+  static_assert(__builtin_strchr(kStr, 'a' - 256) == nullptr);
+  static_assert(__builtin_strchr(kStr, '\xff') == kStr + 4);
+  static_assert(__builtin_strchr(kStr, '\xff' + 256) == nullptr);
+  static_assert(__builtin_strchr(kStr, '\xff' - 256) == nullptr);
+  static_assert(__builtin_strchr(kFoo, 'o') == kFoo + 1);
+  static_assert(__builtin_strchr(kFoo, 'x') == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_strchr(nullptr, 'x') == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+
+  static_assert(__builtin_memchr(kStr, 'a', 0) == nullptr);
+  static_assert(__builtin_memchr(kStr, 'a', 1) == kStr);
+  static_assert(__builtin_memchr(kStr, '\0', 5) == nullptr);
+  static_assert(__builtin_memchr(kStr, '\0', 6) == kStr + 5);
+  static_assert(__builtin_memchr(kStr, '\xff', 8) == kStr + 4);
+  static_assert(__builtin_memchr(kStr, '\xff' + 256, 8) == kStr + 4);
+  static_assert(__builtin_memchr(kStr, '\xff' - 256, 8) == kStr + 4);
+  static_assert(__builtin_memchr(kFoo, 'x', 3) == nullptr);
+  static_assert(__builtin_memchr(kFoo, 'x', 4) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_memchr(nullptr, 'x', 3) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+  static_assert(__builtin_memchr(nullptr, 'x', 0) == nullptr); // FIXME: Should we reject this?
+
+  constexpr bool a = !strchr("hello", 'h'); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strchr' cannot be used in a constant expression}}
+  constexpr bool b = !memchr("hello", 'h', 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'memchr' cannot be used in a constant expression}}
+}