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

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Fri Sep 4 23:04:58 PDT 2026


llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-semantics

Author: laoshd

<details>
<summary>Changes</summary>

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

This PR is to fix #<!-- -->219525.

---
Full diff: https://github.com/llvm/llvm-project/pull/221397.diff


2 Files Affected:

- (modified) flang/lib/Semantics/resolve-names.cpp (+13) 
- (added) flang/test/Semantics/interface-body-data.f90 (+11) 


``````````diff
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

``````````

</details>


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


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