[flang-commits] [flang] [Flang] Fix IsProcedure() for procedure-valued function references (PR #216322)

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https://github.com/keepyixiao updated https://github.com/llvm/llvm-project/pull/216322

>From 1a11c08188dc466f6befb8d4198b7ad36e60baec Mon Sep 17 00:00:00 2001
From: yixiao <yixiao at hygon.cn>
Date: Fri, 14 Aug 2026 21:02:41 +0800
Subject: [PATCH] [Flang] Fix IsProcedure() for procedure-valued function
 references

IsProcedure() does not recognize function references whose results are
procedures. This can cause an assertion failure in intrinsic argument
checking when such an expression is passed as an actual argument.

Update IsProcedure() to inspect the result symbol of a ProcedureRef
and determine whether the function result is a procedure.

Add a regression test for procedure-valued function references.
---
 flang/lib/Evaluate/tools.cpp                  | 16 ++++++-
 .../Semantics/func-proc-result-intrinsics.f90 | 47 +++++++++++++++++++
 flang/test/Semantics/func-proc-result.f90     | 30 ++++++++++++
 3 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Semantics/func-proc-result-intrinsics.f90

diff --git a/flang/lib/Evaluate/tools.cpp b/flang/lib/Evaluate/tools.cpp
index 589aab5132a65..5c436b5a3b326 100644
--- a/flang/lib/Evaluate/tools.cpp
+++ b/flang/lib/Evaluate/tools.cpp
@@ -1003,7 +1003,21 @@ bool IsProcedurePointer(const Expr<SomeType> &expr) {
 }
 
 bool IsProcedure(const Expr<SomeType> &expr) {
-  return IsProcedureDesignator(expr) || IsProcedurePointer(expr);
+  if (IsProcedureDesignator(expr) || IsProcedurePointer(expr)) {
+    return true;
+  }
+  // Also look through a reference to a function whose result is a
+  // procedure, mirroring the function-reference handling in
+  // IsProcedurePointer() above. (Matters for expressions produced
+  // during error recovery.)
+  if (const auto *funcRef{UnwrapProcedureRef(expr)}) {
+    if (const Symbol *proc{funcRef->proc().GetSymbol()}) {
+      if (const Symbol *result{FindFunctionResult(*proc)}) {
+        return IsProcedure(*result);
+      }
+    }
+  }
+  return false;
 }
 
 bool IsProcedurePointerTarget(const Expr<SomeType> &expr) {
diff --git a/flang/test/Semantics/func-proc-result-intrinsics.f90 b/flang/test/Semantics/func-proc-result-intrinsics.f90
new file mode 100644
index 0000000000000..3453e33df0c43
--- /dev/null
+++ b/flang/test/Semantics/func-proc-result-intrinsics.f90
@@ -0,0 +1,47 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+! A reference to a function whose result is a plain procedure (invalid:
+! a function result is either a variable or a procedure pointer, F2023
+! 19.3.3), passed to various intrinsics: each must produce an accurate
+! argument error instead of an assertion failure.
+
+function s1(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'a=' may not be a procedure
+  print *, rank(s1(dd))
+end
+
+function s2(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'source=' may not be a procedure
+  print *, shape(s2(dd))
+end
+
+function s3(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'array=' may not be a procedure
+  print *, size(s3(dd), 1)
+end
+
+function s4(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'a=' may not be a procedure
+  print *, storage_size(s4(dd))
+end
+
+function s5(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'source=' may not be a procedure
+  print *, transfer(s5(dd), 0)
+end
+
+function s6(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'array=' may not be a procedure
+  print *, lbound(s6(dd), 1)
+end
diff --git a/flang/test/Semantics/func-proc-result.f90 b/flang/test/Semantics/func-proc-result.f90
index 5bf8ac9c4ddea..eb887e42471af 100644
--- a/flang/test/Semantics/func-proc-result.f90
+++ b/flang/test/Semantics/func-proc-result.f90
@@ -16,3 +16,33 @@ function bad2() result(res2)
   !ERROR: EXTERNAL attribute not allowed on 'res2'
   external res2
 end
+
+function s(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Actual argument for 'array=' may not be a procedure
+  print *, size(S(dd))
+end
+
+! A procedure POINTER result is valid, but a reference to such a function
+! is still not acceptable as an intrinsic array argument.
+function s1(x) result(i)
+  procedure(), pointer :: i
+  !ERROR: Actual argument for 'array=' may not be a procedure
+  print *, size(S1(dd))
+end
+
+function s2(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Output item must not be a procedure
+  print *, s2(dd)
+end
+
+function s3(x) result(i)
+  !ERROR: A function result may not be a procedure unless it is a procedure pointer
+  procedure() :: i
+  !ERROR: Selector may not be a procedure
+  select type (y => s3(dd))
+  end select
+end