PUBLIC Never mind, turns out this was because OmitInterfacePragmas is turned on by default... (why?). After unsetting OmitInterfacePragmas in the dflags, I get the expected unfolding, and inter-module inlining works. Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=1,unsat_ok=False,boring_ok=False) Tmpl= \ (ds [Occ=Once1!] :: A) -> case ds of { A1 -> B1; A2 -> B2 }} From: Erdi, Gergo Sent: Wednesday, September 1, 2021 4:53 PM To: 'GHC' Cc: Montelatici, Raphael Laurent ; 'gergo@erdi.hu' Subject: Inter-module inlining doesn't work, Id unfolding seems to be empty -- why? PUBLIC Hi, The attached program uses the GHC 9.0.1 API to typecheck and compile a single module that contains a single definition marked as INLINE: module Inline where data A = A1 | A2 data B = B1 | B2 {-# INLINE f #-} f :: A ->B f A1 = B1 f A2 = B2 In my bigger program, I noticed that usages of `f` in another module aren't inlined, so I made the attached experiment: I compile this to desugared, simplified, tidied and prep'd Core, and then use updateModDetailsIdInfos to fill in the unfolding of `f`. At least, that's what I thought I do. However, if I print the unfolding of `f` after this process, I get `OtherCon []` instead of what I expected to be a CoreUnfolding. What am I doing wrong? Thanks, Gergo This email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please delete all copies and notify the sender immediately. You may wish to refer to the incorporation details of Standard Chartered PLC, Standard Chartered Bank and their subsidiaries at https: //www.sc.com/en/our-locations Where you have a Financial Markets relationship with Standard Chartered PLC, Standard Chartered Bank and their subsidiaries (the "Group"), information on the regulatory standards we adhere to and how it may affect you can be found in our Regulatory Compliance Statement at https: //www.sc.com/rcs/ and Regulatory Compliance Disclosures at http: //www.sc.com/rcs/fm Insofar as this communication is not sent by the Global Research team and contains any market commentary, the market commentary has been prepared by the sales and/or trading desk of Standard Chartered Bank or its affiliate. It is not and does not constitute research material, independent research, recommendation or financial advice. Any market commentary is for information purpose only and shall not be relied on for any other purpose and is subject to the relevant disclaimers available at https: //www.sc.com/en/regulatory-disclosures/#market-disclaimer. Insofar as this communication is sent by the Global Research team and contains any research materials prepared by members of the team, the research material is for information purpose only and shall not be relied on for any other purpose, and is subject to the relevant disclaimers available at https: //research.sc.com/research/api/application/static/terms-and-conditions. Insofar as this e-mail contains the term sheet for a proposed transaction, by responding affirmatively to this e-mail, you agree that you have understood the terms and conditions in the attached term sheet and evaluated the merits and risks of the transaction. We may at times also request you to sign the term sheet to acknowledge the same. Please visit https: //www.sc.com/en/regulatory-disclosures/dodd-frank/ for important information with respect to derivative products.