[flang-commits] [flang] b7e13ab - [flang][docs] Document technique for regenerating a module hermetically (#139975)

[via flang-commits]

Author: Peter Klausler
Date: 2025-05-15T11:26:21-07:00
New Revision: b7e13ab42929562d0fa78b623562341ef78617b4

URL: https://github.com/llvm/llvm-project/commit/b7e13ab42929562d0fa78b623562341ef78617b4
DIFF: https://github.com/llvm/llvm-project/commit/b7e13ab42929562d0fa78b623562341ef78617b4.diff

LOG: [flang][docs] Document technique for regenerating a module hermetically (#139975)

A flang-new module file is Fortran source, so it can be recompiled with
the `-fhermetic-module-files` option to convert it into a hermetic one.

Added: 
    

Modified: 
    flang/docs/ModFiles.md

Removed: 
    


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diff  --git a/flang/docs/ModFiles.md b/flang/docs/ModFiles.md
index dd0ade5cebbfc..fc05c2677fc26 100644
--- a/flang/docs/ModFiles.md
+++ b/flang/docs/ModFiles.md
@@ -171,3 +171,14 @@ modules of dependent libraries need not also be packaged with the library.
 When the compiler reads a hermetic module file, the copies of the dependent
 modules are read into their own scope, and will not conflict with other modules
 of the same name that client code might `USE`.
+
+One can use the `-fhermetic-module-files` option when building the top-level
+module files of a library for which not all of the implementation modules
+will (or can) be shipped.
+
+It is also possible to convert a default module file to a hermetic one after
+the fact.
+Since module files are Fortran source, simply copy the module file to a new
+temporary free form Fortran source file and recompile it (`-fsyntax-only`)
+with the `-fhermetic-module-files` flag, and that will regenerate the module
+file in place with all of its dependent modules included.