[flang-commits] [flang] eefe142 - [flang][NFC] Document an intentional violation of the ISO standard (#172105)

[via flang-commits]

Author: Peter Klausler
Date: 2025-12-16T08:11:18-08:00
New Revision: eefe1421122709da60ed2cc30a34b02624049486

URL: https://github.com/llvm/llvm-project/commit/eefe1421122709da60ed2cc30a34b02624049486
DIFF: https://github.com/llvm/llvm-project/commit/eefe1421122709da60ed2cc30a34b02624049486.diff

LOG: [flang][NFC] Document an intentional violation of the ISO standard (#172105)

This compiler (like all others) allows OPTIONAL dummy arguments to
appear as arguments to some intrinsic functions that are specified as
disallowing them; document this interpretation better.

Added: 
    

Modified: 
    flang/docs/Extensions.md

Removed: 
    


################################################################################
diff  --git a/flang/docs/Extensions.md b/flang/docs/Extensions.md
index 593cd99147515..6628597923fc4 100644
--- a/flang/docs/Extensions.md
+++ b/flang/docs/Extensions.md
@@ -189,6 +189,21 @@ end
   `PROCEDURE(), POINTER, NOPASS` derived type components.
   Such procedures may *not* be referenced as implicitly typed functions
   without first being associated with a function pointer.
+* Some intrinsic functions (`COUNT`, `LBOUND`, `LCOBOUND`, `TRANSFER`,
+  `UBOUND`, and `UCOBOUND`) have arguments (usually `DIM=`) that are documented
+  as not allowing `OPTIONAL` dummy arguments to appear as their values.
+  This prohibition appeared on the `DIM=` arguments of more
+  intrinsic functions in earlier revisions of the ISO standard.
+  (Perhaps these are meant to avoid misunderstanding these arguments,
+  which appear in square brackets in the synopses, as if their dynamic
+  presence at runtime could affect the semantics of the intrinsic in
+  the same way as the static presence or absence of the argument does
+  at compilation time, which would not be possible.)
+  No compiler seems to enforce this requirement.
+  We interpret it
+  to mean that an `OPTIONAL` dummy argument may appear but must be present
+  during execution, just as a pointer argument must be associated or an
+  allocatable argument must be allocated.
 
 ## Extensions, deletions, and legacy features supported by default