[clang] 1609632 - [clang][Docs] Add release note for {target}-none-{environment} triple normalization changes (#90734)

[via cfe-commits]

Author: David Spickett
Date: 2024-05-02T08:44:32+01:00
New Revision: 16096325a5ff66d26b7e3424e7fac029c3dd35ea

URL: https://github.com/llvm/llvm-project/commit/16096325a5ff66d26b7e3424e7fac029c3dd35ea
DIFF: https://github.com/llvm/llvm-project/commit/16096325a5ff66d26b7e3424e7fac029c3dd35ea.diff

LOG: [clang][Docs] Add release note for {target}-none-{environment} triple normalization changes (#90734)

That were implemented by
https://github.com/llvm/llvm-project/pull/89638.

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 818dce8fb83b9e..85f7144a27caac 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -90,6 +90,25 @@ Clang Frontend Potentially Breaking Changes
   of ``-Wno-gnu-binary-literal`` will no longer silence this pedantic warning,
   which may break existing uses with ``-Werror``.
 
+- The normalization of 3 element target triples where ``-none-`` is the middle
+  element has changed. For example, ``armv7m-none-eabi`` previously normalized
+  to ``armv7m-none-unknown-eabi``, with ``none`` for the vendor and ``unknown``
+  for the operating system. It now normalizes to ``armv7m-unknown-none-eabi``,
+  which has ``unknown`` vendor and ``none`` operating system.
+
+  The affected triples are primarily for bare metal Arm where it is intended
+  that ``none`` means that there is no operating system. As opposed to an unknown
+  type of operating system.
+
+  This change my cause clang to not find libraries, or libraries to be built at
+  
diff erent file system locations. This can be fixed by changing your builds to
+  use the new normalized triple. However, we recommend instead getting the
+  normalized triple from clang itself, as this will make your builds more
+  robust in case of future changes::
+
+    $ clang --target=<your target triple> -print-target-triple
+    <the normalized target triple>
+
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