[flang] Fix missed case of symbol renaming in module file generation

[klausler]

The map of symbols requiring new local aliases for USE association needs to use the symbols' ultimate resolutions to avoid missing cases that can arise in convoluted codes with lots of confusing renamings.

Fixes #132435.

[llvmbot]

@llvm/pr-subscribers-flang-semantics

Author: Peter Klausler (klausler)

Changes

The map of symbols requiring new local aliases for USE association needs to use the symbols' ultimate resolutions to avoid missing cases that can arise in convoluted codes with lots of confusing renamings.

Fixes #132435.

---

Full diff: https://github.com/llvm/llvm-project/pull/132475.diff

3 Files Affected:

• (modified) flang/lib/Evaluate/formatting.cpp (+2-1)
• (modified) flang/lib/Semantics/mod-file.cpp (+1-1)
• (added) flang/test/Semantics/bug132435.f90 (+85)

diff --git a/flang/lib/Evaluate/formatting.cpp b/flang/lib/Evaluate/formatting.cpp
index c4c3998257830..6778fac9a44fd 100644
--- a/flang/lib/Evaluate/formatting.cpp
+++ b/flang/lib/Evaluate/formatting.cpp
@@ -129,7 +129,8 @@ llvm::raw_ostream &Constant<Type<TypeCategory::Character, KIND>>::AsFortran(
 llvm::raw_ostream &EmitVar(llvm::raw_ostream &o, const Symbol &symbol,
     std::optional<parser::CharBlock> name = std::nullopt) {
   const auto &renamings{symbol.owner().context().moduleFileOutputRenamings()};
-  if (auto iter{renamings.find(&symbol)}; iter != renamings.end()) {
+  if (auto iter{renamings.find(&symbol.GetUltimate())};
+      iter != renamings.end()) {
     return o << iter->second.ToString();
   } else if (name) {
     return o << name->ToString();
diff --git a/flang/lib/Semantics/mod-file.cpp b/flang/lib/Semantics/mod-file.cpp
index c3b46261228df..ee356e56e4458 100644
--- a/flang/lib/Semantics/mod-file.cpp
+++ b/flang/lib/Semantics/mod-file.cpp
@@ -348,7 +348,7 @@ void ModFileWriter::PrepareRenamings(const Scope &scope) {
     uses_ << DEREF(sMod->symbol()).name() << ",only:";
     if (rename != s->name()) {
       uses_ << rename << "=>";
-      renamings.emplace(&*s, rename);
+      renamings.emplace(&s->GetUltimate(), rename);
     }
     uses_ << s->name() << '\n';
     useExtraAttrs_ << "private::" << rename << '\n';
diff --git a/flang/test/Semantics/bug132435.f90 b/flang/test/Semantics/bug132435.f90
new file mode 100644
index 0000000000000..be8b661fcf6cc
--- /dev/null
+++ b/flang/test/Semantics/bug132435.f90
@@ -0,0 +1,85 @@
+! RUN: %python %S/test_modfile.py %s %flang_fc1
+module m1
+  type foo
+    integer :: c1 = 123
+  end type
+end
+
+module m2
+  use m1, only: foo
+  type baz
+    type(foo) :: d = foo()
+  end type
+  type bar
+    type(baz) :: e = baz()
+  end type
+end
+
+module m3
+  use m1, only: m1foo => foo
+  type foo
+    type(m1foo), private :: c2 = m1foo()
+  end type
+end
+
+module m4
+  use m2, only: m3foo => foo
+  type foo
+    type(m3foo), private :: c3 = m3foo()
+  end type
+end
+
+module m5
+  use m2, only: m2bar => bar
+  use m4, only: foo
+  type blah
+    type(m2bar) :: f = m2bar()
+  end type
+end
+
+!Expect: m1.mod
+!module m1
+!type::foo
+!integer(4)::c1=123_4
+!end type
+!end
+
+!Expect: m2.mod
+!module m2
+!use m1,only:foo
+!type::baz
+!type(foo)::d=foo(c1=123_4)
+!end type
+!type::bar
+!type(baz)::e=baz(d=foo(c1=123_4))
+!end type
+!end
+
+!Expect: m3.mod
+!module m3
+!use m1,only:m1foo=>foo
+!type::foo
+!type(m1foo),private::c2=m1foo(c1=123_4)
+!end type
+!end
+
+!Expect: m4.mod
+!module m4
+!use m2,only:m3foo=>foo
+!type::foo
+!type(m3foo),private::c3=m3foo(c1=123_4)
+!end type
+!end
+
+!Expect: m5.mod
+!module m5
+!use m2,only:m2$foo=>foo
+!use m2,only:baz
+!use m2,only:m2bar=>bar
+!use m4,only:foo
+!private::m2$foo
+!private::baz
+!type::blah
+!type(m2bar)::f=m2bar(e=baz(d=m2$foo(c1=123_4)))
+!end type
+!end

[pawosm-arm]

considering importance of CP2K in the Fortran world, I'd suggest cherrypicking to LLVM20 release branch.

[pawosm-arm]

/cherry-pick 6df27dd

[llvmbot]

/pull-request #133223