[flang-commits] [flang] [FLANG][Semantics] Add check for DATA statement in interface body. (PR #221397)

[via flang-commits]

https://github.com/laoshd created https://github.com/llvm/llvm-project/pull/221397

Will check and reject DATA statements in interface bodies before lowering. A regression test is also added.

This PR is to fix #219525.

>From e6a35d039bc6cb04c51623a269156de75d00b919 Mon Sep 17 00:00:00 2001
From: Shandong Lao <shandong.lao at hpe.com>
Date: Sat, 5 Sep 2026 00:58:45 -0500
Subject: [PATCH] [FLANG][Semantics] Add check for DATA statement in interface
 body.

Will check and reject DATA statements in interface bodies before lowering. A regression test is also added.
---
 flang/lib/Semantics/resolve-names.cpp        | 13 +++++++++++++
 flang/test/Semantics/interface-body-data.f90 | 11 +++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 flang/test/Semantics/interface-body-data.f90

diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index 6517232a1e21c..1b70985066ac7 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -1356,6 +1356,7 @@ class ConstructVisitor : public virtual DeclarationVisitor {
   bool Pre(const parser::AcSpec &);
   bool Pre(const parser::AcImpliedDo &);
   bool Pre(const parser::DataImpliedDo &);
+  bool Pre(const parser::DataStmt &);
   bool Pre(const parser::DataIDoObject &);
   bool Pre(const parser::DataStmtObject &);
   bool Pre(const parser::DataStmtValue &);
@@ -8922,6 +8923,18 @@ bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
   return false;
 }
 
+bool ConstructVisitor::Pre(const parser::DataStmt &) {
+  // C1506: an interface body may not contain a DATA statement.
+  if (const Symbol *symbol{currScope().symbol()}) {
+    if (const auto *subp{symbol->detailsIf<SubprogramDetails>()};
+        subp && subp->isInterface()) {
+      Say(currStmtSource().value(),
+          "A DATA statement may not appear in an interface body"_err_en_US);
+    }
+  }
+  return true;
+}
+
 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
diff --git a/flang/test/Semantics/interface-body-data.f90 b/flang/test/Semantics/interface-body-data.f90
new file mode 100644
index 0000000000000..bdd522ed0eee8
--- /dev/null
+++ b/flang/test/Semantics/interface-body-data.f90
@@ -0,0 +1,11 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+
+interface
+  subroutine s
+    integer :: x
+    !ERROR: A DATA statement may not appear in an interface body
+    data x /1/
+  end subroutine
+end interface
+
+end
\ No newline at end of file