[flang-commits] [flang] [flang] Avoid crash on conflicting BIND(C) declaration (PR #231816)

[via flang-commits]

https://github.com/Anastasia-Artemova created https://github.com/llvm/llvm-project/pull/231816

Fixes [llvm/llvm-project#229729.](https://github.com/llvm/llvm-project/issues/229729)

This PR addresses a Flang crash that occurs when a scalar variable with the BIND(C) attribute conflicts with an existing derived-type declaration.

>From 87899de447e0df2a0c14efad9a0b044a07899432 Mon Sep 17 00:00:00 2001
From: Anastasia-Artemova <anastasia.r.artemova at gmail.com>
Date: Wed, 14 Oct 2026 10:41:21 +0200
Subject: [PATCH] [flang] Avoid crash on conflicting BIND(C) declaration

---
 flang/lib/Semantics/resolve-names.cpp | 2 +-
 flang/test/Semantics/bind-c22.f90     | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Semantics/bind-c22.f90

diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index 67690d6f47d06..903cb14b6d902 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -6831,7 +6831,7 @@ Symbol &DeclarationVisitor::DeclareUnknownEntity(
                    Attr::SAVE, Attr::TARGET, Attr::VALUE, Attr::VOLATILE})) {
       ConvertToObjectEntity(symbol);
     }
-    if (attrs.test(Attr::BIND_C)) {
+    if (attrs.test(Attr::BIND_C) && !context().HasError(symbol)) {
       SetBindNameOn(symbol);
     }
     return symbol;
diff --git a/flang/test/Semantics/bind-c22.f90 b/flang/test/Semantics/bind-c22.f90
new file mode 100644
index 0000000000000..2a8530b8be2e7
--- /dev/null
+++ b/flang/test/Semantics/bind-c22.f90
@@ -0,0 +1,8 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+
+module bind_c_conflicting_type_name
+  type :: x
+  end type
+  !ERROR: 'x' is already declared in this scoping unit
+  integer, bind(c) :: x
+end module