[flang] Catch both EXTERNAL and INTRINSIC on type declaration stmt

[klausler]

The EXTERNAL and INTRINSIC attributes can't both appear on the same type declarations statement.

Fixes #149771.

[llvmbot]

@llvm/pr-subscribers-flang-semantics

Author: Peter Klausler (klausler)

Changes

The EXTERNAL and INTRINSIC attributes can't both appear on the same type declarations statement.

Fixes #149771.

---

Full diff: https://github.com/llvm/llvm-project/pull/150254.diff

2 Files Affected:

• (modified) flang/lib/Semantics/resolve-names.cpp (+2-1)
• (added) flang/test/Semantics/resolve126.f90 (+7)

diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index b3268605e7c0c..d08c669377cb2 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -2351,7 +2351,8 @@ bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
-      HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
+      HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE) ||
+      HaveAttrConflict(attrName, Attr::INTRINSIC, Attr::EXTERNAL);
 }
 bool AttrsVisitor::CheckAndSet(Attr attrName) {
   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
diff --git a/flang/test/Semantics/resolve126.f90 b/flang/test/Semantics/resolve126.f90
new file mode 100644
index 0000000000000..6313f8c539bf8
--- /dev/null
+++ b/flang/test/Semantics/resolve126.f90
@@ -0,0 +1,7 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+!ERROR: Attributes 'INTRINSIC' and 'EXTERNAL' conflict with each other
+real, external, intrinsic :: exp
+!ERROR: Symbol 'sin' cannot have both EXTERNAL and INTRINSIC attributes
+external sin
+intrinsic sin
+end

[c8ef]

Nit: Add a comment stating it violates C842(F2023)?