Add __has_builtin support for builtin function-like type traits.

Summary:
Previously __has_builtin(__builtin_*) would return false for
__builtin_*s that we modeled as keywords rather than as functions
(because they take type arguments). With this patch, all builtins
that are called with function-call-like syntax return true from
__has_builtin (covering __builtin_* and also the __is_* and __has_* type
traits and the handful of similar builtins without such a prefix).

Update the documentation on __has_builtin and on type traits to match.
While doing this I noticed the type trait documentation was out of date
and incomplete; that's fixed here too.

Reviewers: aaron.ballman

Subscribers: jfb, kristina, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66100

llvm-svn: 368785

1 files changed, 43 insertions, 0 deletions

diff --git a/clang/test/Preprocessor/feature_tests.cpp b/clang/test/Preprocessor/feature_tests.cpp
new file mode 100644
index 00000000000..50da228a4ef
--- /dev/null
+++ b/clang/test/Preprocessor/feature_tests.cpp
@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 %s -triple=i686-apple-darwin9 -verify -DVERIFY
+// expected-no-diagnostics
+
+#ifndef __has_feature
+#error Should have __has_feature
+#endif
+
+#if __has_feature(something_we_dont_have)
+#error Bad
+#endif
+
+#if  !__has_builtin(__builtin_huge_val) || \
+     !__has_builtin(__builtin_shufflevector) || \
+     !__has_builtin(__builtin_convertvector) || \
+     !__has_builtin(__builtin_trap) || \
+     !__has_builtin(__c11_atomic_init) || \
+     !__has_builtin(__builtin_launder) || \
+     !__has_feature(attribute_analyzer_noreturn) || \
+     !__has_feature(attribute_overloadable)
+#error Clang should have these
+#endif
+
+// These are technically implemented as keywords, but __has_builtin should
+// still return true.
+#if !__has_builtin(__builtin_LINE) || \
+    !__has_builtin(__builtin_FILE) || \
+    !__has_builtin(__builtin_FUNCTION) || \
+    !__has_builtin(__builtin_COLUMN) || \
+    !__has_builtin(__array_rank) || \
+    !__has_builtin(__underlying_type) || \
+    !__has_builtin(__is_trivial) || \
+    !__has_builtin(__has_unique_object_representations)
+#error Clang should have these
+#endif
+
+// This is a C-only builtin.
+#if __has_builtin(__builtin_types_compatible_p)
+#error Clang should not have this in C++ mode
+#endif
+
+#if __has_builtin(__builtin_insanity)
+#error Clang should not have this
+#endif