Implement __builtin_LINE() et. al. to support source location capture.
Summary:
This patch implements the source location builtins `__builtin_LINE(), `__builtin_FUNCTION()`, `__builtin_FILE()` and `__builtin_COLUMN()`. These builtins are needed to implement [`std::experimental::source_location`](https://rawgit.com/cplusplus/fundamentals-ts/v2/main.html#reflection.src_loc.creation).
With the exception of `__builtin_COLUMN`, GCC also implements these builtins, and Clangs behavior is intended to match as closely as possible.
Reviewers: rsmith, joerg, aaron.ballman, bogner, majnemer, shafik, martong
Reviewed By: rsmith
Subscribers: rnkovacs, loskutov, riccibruno, mgorny, kunitoki, alexr, majnemer, hfinkel, cfe-commits
Differential Revision: https://reviews.llvm.org/D37035
llvm-svn: 360937
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 7772bf5..9871c23 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2300,6 +2300,61 @@
token `none`. If a user calls `__builin_suspend`, clang will insert `token none`
as the first argument to the intrinsic.
+Source location builtins
+------------------------
+
+Clang provides experimental builtins to support C++ standard library implementation
+of ``std::experimental::source_location`` as specified in http://wg21.link/N4600.
+With the exception of ``__builtin_COLUMN``, these builtins are also implemented by
+GCC.
+
+**Syntax**:
+
+.. code-block:: c
+
+ const char *__builtin_FILE();
+ const char *__builtin_FUNCTION();
+ unsigned __builtin_LINE();
+ unsigned __builtin_COLUMN(); // Clang only
+
+**Example of use**:
+
+.. code-block:: c++
+
+ void my_assert(bool pred, int line = __builtin_LINE(), // Captures line of caller
+ const char* file = __builtin_FILE(),
+ const char* function = __builtin_FUNCTION()) {
+ if (pred) return;
+ printf("%s:%d assertion failed in function %s\n", file, line, function);
+ std::abort();
+ }
+
+ struct MyAggregateType {
+ int x;
+ int line = __builtin_LINE(); // captures line where aggregate initialization occurs
+ };
+ static_assert(MyAggregateType{42}.line == __LINE__);
+
+ struct MyClassType {
+ int line = __builtin_LINE(); // captures line of the constructor used during initialization
+ constexpr MyClassType(int) { assert(line == __LINE__); }
+ };
+
+**Description**:
+
+The builtins ``__builtin_LINE``, ``__builtin_FUNCTION``, and ``__builtin_FILE`` return
+the values, at the "invocation point", for ``__LINE__``, ``__FUNCTION__``, and
+``__FILE__`` respectively. These builtins are constant expressions.
+
+When the builtins appear as part of a default function argument the invocation
+point is the location of the caller. When the builtins appear as part of a
+default member initializer, the invocation point is the location of the
+constructor or aggregate initialization used to create the object. Otherwise
+the invocation point is the same as the location of the builtin.
+
+When the invocation point of ``__builtin_FUNCTION`` is not a function scope the
+empty string is returned.
+
Non-standard C++11 Attributes
=============================