[flang][Semantics] Fix ICE when compiling a mod file with parameter w…

[JDPailleux]

…ithout type specified

Fatal internal error occurred when compiling a mod file with a subroutine which contain a parameter with no
explicit type.

Ex:

   module inform
      implicit none
      interface normp
         module subroutine normt( array, n, val,p )
         integer siz
         integer,optional::p
         real*8 array(*)
         real*8 val
         end subroutine
      end interface
   end

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[llvmbot]

@llvm/pr-subscribers-flang-semantics

Author: Jean-Didier PAILLEUX (JDPailleux)

Changes

…ithout type specified

Fatal internal error occurred when compiling a mod file with a subroutine which contain a parameter with no
explicit type.

Ex:

   module inform
      implicit none
      interface normp
         module subroutine normt( array, n, val,p )
         integer siz
         integer,optional::p
         real*8 array(*)
         real*8 val
         end subroutine
      end interface
   end

---

Full diff: https://github.com/llvm/llvm-project/pull/124285.diff

2 Files Affected:

• (modified) flang/lib/Semantics/mod-file.cpp (+7-1)
• (added) flang/test/Semantics/modfile_missing_type.f90 (+14)

diff --git a/flang/lib/Semantics/mod-file.cpp b/flang/lib/Semantics/mod-file.cpp
index 51ff70c3ed8341..7a60e22de726e7 100644
--- a/flang/lib/Semantics/mod-file.cpp
+++ b/flang/lib/Semantics/mod-file.cpp
@@ -955,7 +955,13 @@ void ModFileWriter::PutObjectEntity(
     }
   }
   PutEntity(
-      os, symbol, [&]() { PutType(os, DEREF(symbol.GetType())); },
+      os, symbol,
+      [&]() {
+        // Need to check if there is a TYPE on this symbol to avoid any ICE
+        if (details.type()) {
+          PutType(os, DEREF(symbol.GetType()));
+        }
+      },
       getSymbolAttrsToWrite(symbol));
   PutShape(os, details.shape(), '(', ')');
   PutShape(os, details.coshape(), '[', ']');
diff --git a/flang/test/Semantics/modfile_missing_type.f90 b/flang/test/Semantics/modfile_missing_type.f90
new file mode 100644
index 00000000000000..fda19372b8993f
--- /dev/null
+++ b/flang/test/Semantics/modfile_missing_type.f90
@@ -0,0 +1,14 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+! Test to check that this module can be compiled when an argument has no specified type
+module inform
+  implicit none
+  interface normp
+     module subroutine normt( array,n,val,p )
+     integer siz
+     integer,optional::p
+     real*8 array(*)
+     real*8 val
+     end subroutine
+  end interface
+end
+

[klausler]

This DEREF is not the bug. The bug is that the symbol has no type after name resolution, but must have one. The DEREF() here is catching the bug, and it must remain in place.