[flang] Fix crash on SMP with dummy procedure

[klausler]

When a separate module procedure is defined with MODULE PROCEDURE, the compiler crashes if there is a dummy procedure in the interface defined with only a result type. This is due to the type already having been defined on the ProcEntityDetails symbol as part of earlier wholesale symbol duplication. Adjust the code to not define the result type of the ProcEntityDetails if it is already present, but to verify that it is the same type instead.

Fixes #124487.

[llvmbot]

@llvm/pr-subscribers-flang-semantics

Author: Peter Klausler (klausler)

Changes

When a separate module procedure is defined with MODULE PROCEDURE, the compiler crashes if there is a dummy procedure in the interface defined with only a result type. This is due to the type already having been defined on the ProcEntityDetails symbol as part of earlier wholesale symbol duplication. Adjust the code to not define the result type of the ProcEntityDetails if it is already present, but to verify that it is the same type instead.

Fixes #124487.

---

Full diff: https://github.com/llvm/llvm-project/pull/124663.diff

2 Files Affected:

• (modified) flang/lib/Semantics/resolve-names-utils.cpp (+5-1)
• (added) flang/test/Semantics/bug124487.f90 (+13)

diff --git a/flang/lib/Semantics/resolve-names-utils.cpp b/flang/lib/Semantics/resolve-names-utils.cpp
index a838d49c06104d..347f54e0640705 100644
--- a/flang/lib/Semantics/resolve-names-utils.cpp
+++ b/flang/lib/Semantics/resolve-names-utils.cpp
@@ -762,7 +762,11 @@ void SymbolMapper::MapSymbolExprs(Symbol &symbol) {
               proc.set_procInterfaces(
                   *mappedSymbol, BypassGeneric(mappedSymbol->GetUltimate()));
             } else if (const DeclTypeSpec * mappedType{MapType(proc.type())}) {
-              proc.set_type(*mappedType);
+              if (proc.type()) {
+                CHECK(*proc.type() == *mappedType);
+              } else {
+                proc.set_type(*mappedType);
+              }
             }
             if (proc.init()) {
               if (const Symbol * mapped{MapSymbol(*proc.init())}) {
diff --git a/flang/test/Semantics/bug124487.f90 b/flang/test/Semantics/bug124487.f90
new file mode 100644
index 00000000000000..867f6e30beb5d1
--- /dev/null
+++ b/flang/test/Semantics/bug124487.f90
@@ -0,0 +1,13 @@
+!RUN: %flang_fc1 -fsyntax-only %s 2>&1 | FileCheck --allow-empty %s
+module m
+  interface
+    module subroutine smp(x)
+      character, external :: x
+    end
+  end interface
+end
+submodule (m) sm
+ contains
+  module procedure smp ! crashes here
+  end
+end