[flang-commits] [flang] [flang] Recognize IARGC and GETARG as aliases for F2003 intrinsics (PR #173973)

[via flang-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-semantics

Author: None (Vinayak-RZ)

<details>
<summary>Changes</summary>

This patch fixes a semantic issue where the GNU Fortran compatibility
intrinsics IARGC and GETARG were not recognized under IMPLICIT NONE,
despite being available in the Flang runtime.

The change registers both names as aliases for their Fortran 2003
standard equivalents, restoring compatibility with legacy code
without changing lowering or runtime behavior.

Fixes #<!-- -->158438.

---
Full diff: https://github.com/llvm/llvm-project/pull/173973.diff


3 Files Affected:

- (modified) flang/docs/Extensions.md (+3) 
- (modified) flang/lib/Evaluate/intrinsics.cpp (+2) 
- (added) flang/test/Semantics/intrinsic-alias-implicit-none.f90 (+17) 


``````````diff
diff --git a/flang/docs/Extensions.md b/flang/docs/Extensions.md
index 82822d5a143d2..57c58f567aa56 100644
--- a/flang/docs/Extensions.md
+++ b/flang/docs/Extensions.md
@@ -381,6 +381,9 @@ end
 * Legacy names `AND`, `OR`, and `XOR` are accepted as aliases for
   the standard intrinsic functions `IAND`, `IOR`, and `IEOR`
   respectively.
+* Legacy GNU intrinsics `IARGC` and `GETARG` are accepted as aliases for
+  the standard intrinsics `COMMAND_ARGUMENT_COUNT` and
+  `GET_COMMAND_ARGUMENT`, respectively.
 * A digit count of d=0 is accepted in Ew.0, Dw.0, and Gw.0 output
   editing if no nonzero scale factor (kP) is in effect.
 * The name `IMAG` is accepted as an alias for the generic intrinsic
diff --git a/flang/lib/Evaluate/intrinsics.cpp b/flang/lib/Evaluate/intrinsics.cpp
index 72ac9e2f68758..1a66e7576d61f 100644
--- a/flang/lib/Evaluate/intrinsics.cpp
+++ b/flang/lib/Evaluate/intrinsics.cpp
@@ -1164,6 +1164,7 @@ static const IntrinsicInterface genericIntrinsicFunction[]{
 // Aliases for a few generic procedures for legacy compatibility and builtins.
 static const std::pair<const char *, const char *> genericAlias[]{
     {"and", "iand"},
+    {"getarg", "get_command_argument"}, 
     {"getenv", "get_environment_variable"},
     {"fseek64", "fseek"},
     {"fseeko64", "fseek"}, // SUN
@@ -1172,6 +1173,7 @@ static const std::pair<const char *, const char *> genericAlias[]{
     {"ftello64", "ftell"}, // SUN
     {"ftelli8", "ftell"}, // Intel
     {"imag", "aimag"},
+    {"iargc", "command_argument_count"}, 
     {"lshift", "shiftl"},
     {"or", "ior"},
     {"rshift", "shifta"},
diff --git a/flang/test/Semantics/intrinsic-alias-implicit-none.f90 b/flang/test/Semantics/intrinsic-alias-implicit-none.f90
new file mode 100644
index 0000000000000..6b73782028198
--- /dev/null
+++ b/flang/test/Semantics/intrinsic-alias-implicit-none.f90
@@ -0,0 +1,17 @@
+! RUN: %flang_fc1 -fsyntax-only %s
+!
+! Check that GNU Fortran compatibility intrinsics IARGC and GETARG
+! are recognized as intrinsic procedures under IMPLICIT NONE.
+
+program test_intrinsic_aliases
+  implicit none
+
+  integer :: n
+  character(len=100) :: arg
+
+  ! IARGC is an alias for COMMAND_ARGUMENT_COUNT
+  n = iargc()
+
+  ! GETARG is an alias for GET_COMMAND_ARGUMENT
+  call getarg(1, arg)
+end program

``````````

</details>


https://github.com/llvm/llvm-project/pull/173973