From 6e86d8cfb48cf3a56d96b1acb464300759d6c43f Mon Sep 17 00:00:00 2001
From: Yichao Yu <yyc1992@gmail.com>
Date: Thu, 7 Apr 2016 10:23:04 -0400
Subject: [PATCH] Better doc and codegen for noreturn ccall

Closes #14685
---
 doc/manual/calling-c-and-fortran-code.rst | 10 ++++++++++
 src/ccall.cpp                             |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/doc/manual/calling-c-and-fortran-code.rst b/doc/manual/calling-c-and-fortran-code.rst
index ddb85f17a5076..49affe6d61e0c 100644
--- a/doc/manual/calling-c-and-fortran-code.rst
+++ b/doc/manual/calling-c-and-fortran-code.rst
@@ -400,6 +400,9 @@ Julia type with the same name, prefixed by C. This can help for writing portable
 +-----------------------------------+-----------------+----------------------+-----------------------------------+
 | ``void``                          |                 |                      | ``Void``                          |
 +-----------------------------------+-----------------+----------------------+-----------------------------------+
+| ``void`` and                      |                 |                      | ``Union{}``                       |
+| ``[[noreturn]]`` or ``_Noreturn`` |                 |                      |                                   |
++-----------------------------------+-----------------+----------------------+-----------------------------------+
 | ``void*``                         |                 |                      | ``Ptr{Void}``                     |
 +-----------------------------------+-----------------+----------------------+-----------------------------------+
 | ``T*`` (where T represents an     |                 |                      | ``Ref{T}``                        |
@@ -473,6 +476,13 @@ C name                  Standard Julia Alias    Julia Base Type
     Julia's ``Char`` type is 32 bits, which is not the same as the wide character
     type (``wchar_t`` or ``wint_t``) on all platforms.
 
+.. warning::
+
+    A return type of ``Union{}`` means the function will not return
+    i.e. C++11 ``[[noreturn]]`` or C11 ``_Noreturn`` (e.g. ``jl_throw`` or
+    ``longjmp``). Do not use this for function that returns
+    no value (``void``) but does return.
+
 .. note::
 
     For ``wchar_t*`` arguments, the Julia type should be ``Cwstring`` (if the C
diff --git a/src/ccall.cpp b/src/ccall.cpp
index 43f3dc28d635f..753141b00f544 100644
--- a/src/ccall.cpp
+++ b/src/ccall.cpp
@@ -1013,6 +1013,10 @@ static std::string generate_func_sig(
                                                   AttributeSet::get(jl_LLVMContext, i + 1, paramattrs[i]));
         }
     }
+    if (rt == jl_bottom_type)
+        attributes = attributes.addAttribute(jl_LLVMContext,
+                                             AttributeSet::FunctionIndex,
+                                             Attribute::NoReturn);
     return "";
 }