[flang-commits] [flang] 46387cd - [flang] Compile the output of -fdebug-unparse-with-modules (#135696)

[via flang-commits]

Author: Peter Klausler
Date: 2025-04-18T12:48:55-07:00
New Revision: 46387cd18420e120bbcfa3a646d48e2903a5c28c

URL: https://github.com/llvm/llvm-project/commit/46387cd18420e120bbcfa3a646d48e2903a5c28c
DIFF: https://github.com/llvm/llvm-project/commit/46387cd18420e120bbcfa3a646d48e2903a5c28c.diff

LOG: [flang] Compile the output of -fdebug-unparse-with-modules (#135696)

The output of a compilation with the -fdebug-unparse-with-modules option
comprises its normal unparsed output along with the regenerated contents
of any modules that were required from module files. This is handy for
producing stand-alone test cases.

The modules' contents are generated by the same code that writes module
files, so they can contain some USE associations to private entities in
other modules that are necessary to complete local declarations, usually
initializers. Such USE associations to private entities are not flagged
as fatal errors when modules are read from module files, but they
currently are caught when the output produced by this option is being
read back in to the compiler.

Handle this case by softening the error to a warning when one module
uses a private entity from another with an alias containing the
non-conforming '$' character. (I could have omitted the message
altogether, but there are other valid warnings that will occur due to
undefined function result variables; further, I didn't want to provide a
general hole around the protection of private names.)

Added: 
    

Modified: 
    flang/docs/ModFiles.md
    flang/lib/Semantics/resolve-names.cpp
    flang/test/Semantics/resolve11.f90

Removed: 
    


################################################################################
diff  --git a/flang/docs/ModFiles.md b/flang/docs/ModFiles.md
index cde2e4218d6fd..dd0ade5cebbfc 100644
--- a/flang/docs/ModFiles.md
+++ b/flang/docs/ModFiles.md
@@ -98,7 +98,14 @@ Entities that have been included in a module by means of USE association
 are represented in the module file with `USE` statements.
 Name aliases are sometimes necessary when an entity from another
 module is needed for a declaration and conflicts with another
-entity of the same name.
+entity of the same name, or is `PRIVATE`.
+These aliases have currency symbols (`$`) in them.
+When a module
+is parsed from a module file, no error is emitted for associating
+such an alias with a `PRIVATE` name.
+A module parsed from another source file that is not a module file
+(notably, the output of the `-fdebug-unparse-with-modules` option)
+will emit only warnings.
 
 ## Reading and writing module files
 

diff  --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index 74367b5229548..7ec6252530d55 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -3325,9 +3325,19 @@ ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
     // Privacy is not enforced in module files so that generic interfaces
     // can be resolved to private specific procedures in specification
     // expressions.
-    Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
-        useModuleScope_->GetName().value());
-    return {};
+    // Local names that contain currency symbols ('$') are created by the
+    // module file writer when a private name in another module is needed to
+    // process a local declaration.  These can show up in the output of
+    // -fdebug-unparse-with-modules, too, so go easy on them.
+    if (currScope().IsModule() &&
+        localName.ToString().find("$") != std::string::npos) {
+      Say(useName, "'%s' is PRIVATE in '%s'"_warn_en_US, MakeOpName(useName),
+          useModuleScope_->GetName().value());
+    } else {
+      Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
+          useModuleScope_->GetName().value());
+      return {};
+    }
   }
   auto &localSymbol{MakeSymbol(localName)};
   DoAddUse(useName, localName, localSymbol, *useSymbol);

diff  --git a/flang/test/Semantics/resolve11.f90 b/flang/test/Semantics/resolve11.f90
index db508f062d1d1..39a30b858ebb6 100644
--- a/flang/test/Semantics/resolve11.f90
+++ b/flang/test/Semantics/resolve11.f90
@@ -86,3 +86,17 @@ subroutine s5
   use m5, only: foo, fun
   print *, fun() ! ok
 end
+
+module m6
+  !WARNING: 'foo' is PRIVATE in 'm5'
+  use m5, only: name$with$dollar => foo
+  !ERROR: 'foo' is PRIVATE in 'm5'
+  use m5, only: normal_name => foo
+end
+
+subroutine s6
+  !The special dispensation for USE association of private names to local
+  !aliases with '$' in them only applies to modules.
+  !ERROR: 'foo' is PRIVATE in 'm5'
+  use m5, only: name$with$dollar => foo
+end