#10382: Template Haskell quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Description changed by ezyang: Old description:

Right now, you must enable the `TemplateHaskell` extension to use quotes, and `TemplateHaskell` is not supported by the stage 1 compiler. But there actually is no good reason why this should be the case: quoting doesn't require any user-written code to be loaded up and run, so it should be doable by the stage 1 compiler. I propose adding a new extension, `Quotation`, which turns on JUST quotation and works with the stage 1 compiler.

This will solve len's problem https://github.com/ekmett/lens/issues/496 where they want to rename some syntax using quotation, but don't want break compilation on a stage 1 compiler.

See also #10279.

New description: Right now, you must enable the `TemplateHaskell` extension to use quotes, and `TemplateHaskell` is not supported by the stage 1 compiler. But there actually is no good reason why this should be the case: quoting doesn't require any user-written code to be loaded up and run, so it should be doable by the stage 1 compiler. I propose adding a new extension, `Quotes`, which turns on JUST quotation and works with the stage 1 compiler. This will solve len's problem https://github.com/ekmett/lens/issues/496 where they want to rename some syntax using quotation, but don't want break compilation on a stage 1 compiler. See also #10279. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by ezyang): To be clear, I am NOT suggesting quasi-quotes be supported by this; just plain old brackets! (Apologies for the bad names; perhaps "expression quotation" is a more accurate name?) With plain quotes, we don't have to find and link `qq` with this complexity. See the diff that's been attached, which I know works and is not all that complicated. Whether or not the change is parochial, I think it relates to more than just GHC; it applies to any platform where we can compile GHC, but dynamic code loading is not supported (i.e. no GHCi support). Now, you might wonder, "why would anyone need to use TH quotes, without any TH splices?" but Edward Kmett gives an example of one such case, where he wants to put his TH library code (no splices) in a main library, while still supporting platforms without GHCi, without macroing the business. Unusual? Maybe. But someone wants it, and it doesn't seem too hard to give them, so let's do it! If we don't like the language extension, we could alternate make `TemplateHaskell` not immediately error on stage 1 compilation, and just error when we actually reach a splice site. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by ekmett): The current situation: On one hand I have a number of packages that provide `TemplateHaskell` convenience functions for users, `lens` being the go-to example. But on the other hand, I have a bunch of folks who maintain releases for my packages on platforms where only a stage1 compiler is available, Joachim Breitner and the Debian folks used to maintain patches and versions of my code that removed large chunks of the libraries to build on those platforms. When i found out, I offered to support stage1 compilers myself more directly. This ensured a more uniform API, and that different distributions weren't crippling my code in different ways, making it so certain combinators or modules just weren't available on certain platforms. But then we ran into an issue, we needed to generate names that linked to the right places within our code. So we manually construct all of our names ourselves, using the cabal-supplied version number or package key when needed: https://github.com/ekmett/lens/blob/9a247b52ed20e578d9c843d8cc6dad5433a1c186... Then we just don't use the TemplateHaskell extension ourselves, despite linking against the `template-haskell` package and everything is good enough for us to limp along. I would love to eventually be able to drop this set of hoops, but I have few opinions on the best way to get there. That said, Edward's suggestion of making TemplateHaskell just bomb when you reach a splice site in stage1 rather than immediately would avoid introducing any new flags and sounds pretty simple. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by ezyang): I can rewrite the code motion to be added ifdef macros, but it seemed cleaner to just hoist them all out. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by Edward Z. Yang ): In [changeset:"28257cae77023f2ccc4cc1c0cd1fbbd329947a00/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="28257cae77023f2ccc4cc1c0cd1fbbd329947a00" Support stage 1 Template Haskell (non-quasi) quotes, fixes #10382. Summary: This commit adds stage 1 support for Template Haskell quoting, e.g. [| ... expr ... |], which is useful for authors of quasiquoter libraries that do not actually need splices. The TemplateHaskell extension now does not unconditionally fail; it only fails if the renamer encounters a splice that it can't run. In order to make sure the referenced data structures are consistent, template-haskell is now a boot library. In the following patches, there are: - A few extra safety checks which should be enabled in stage1 - Separation of the th/ testsuite into quotes/ which can be run on stage1 Note for reviewer: big diff changes are simply code being moved out of an ifdef; there was no other substantive change to that code. Signed-off-by: Edward Z. Yang Test Plan: validate Reviewers: simonpj, austin, goldfire Subscribers: bgamari, thomie Differential Revision: https://phabricator.haskell.org/D876 GHC Trac Issues: #10382 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by Edward Z. Yang ): In [changeset:"eb0ed4030374af542c0a459480d32c8d4525e48d/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="eb0ed4030374af542c0a459480d32c8d4525e48d" RnSplice's staging test should be applied for quotes in stage1. Signed-off-by: Edward Z. Yang Test Plan: validate Reviewers: simonpj, austin Subscribers: bgamari, thomie Differential Revision: https://phabricator.haskell.org/D878 GHC Trac Issues: #10382 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: closed Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by Edward Z. Yang ): In [changeset:"5c459eefcb17ff97beebdc08ccfca21bd8fa5201/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="5c459eefcb17ff97beebdc08ccfca21bd8fa5201" Revert stage 1 template-haskell. This is a combination of 5 commits. Revert "Quick fix: drop base bound on template-haskell." This reverts commit 3c70ae032e4361b203dfcf22b0a424e8838a5037. Revert "Always do polymorphic typed quote check, c.f. #10384" This reverts commit 9a43b2c1f78b3cf684646af64b9b67dc8079f58f. Revert "RnSplice's staging test should be applied for quotes in stage1." This reverts commit eb0ed4030374af542c0a459480d32c8d4525e48d. Revert "Split off quotes/ from th/ for tests that can be done on stage1 compiler." This reverts commit 21c72e7d38c96ac80d31addf67ae4b3c7a6c3bbb. Revert "Support stage 1 Template Haskell (non-quasi) quotes, fixes #10382." This reverts commit 28257cae77023f2ccc4cc1c0cd1fbbd329947a00. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature request | Status: closed Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.11 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D876 -------------------------------------+------------------------------------- Comment (by Edward Z. Yang ): In [changeset:"f16ddcee0c64a92ab911a7841a8cf64e3ac671fd/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="f16ddcee0c64a92ab911a7841a8cf64e3ac671fd" Support stage 1 Template Haskell (non-quasi) quotes, fixes #10382. Summary: This commit adds stage 1 support for Template Haskell quoting, e.g. [| ... expr ... |], which is useful for authors of quasiquoter libraries that do not actually need splices. The TemplateHaskell extension now does not unconditionally fail; it only fails if the renamer encounters a splice that it can't run. In order to make sure the referenced data structures are consistent, template-haskell is now a boot library. There are some minor BC changes to template-haskell to make it boot on GHC 7.8. Note for reviewer: big diff changes are simply code being moved out of an ifdef; there was no other substantive change to that code. Signed-off-by: Edward Z. Yang Test Plan: validate Reviewers: simonpj, austin, goldfire Subscribers: bgamari, thomie Differential Revision: https://phabricator.haskell.org/D876 GHC Trac Issues: #10382 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: new Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D876 Wiki Page: | -------------------------------------+------------------------------------- Changes (by ezyang): * owner: ezyang => * status: closed => new * resolution: fixed => -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: new Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D876 Wiki Page: | -------------------------------------+------------------------------------- Comment (by thomie): Replying to [comment:20 ezyang]:

We also need a way to force the test suite to run stage1 in some cases, so we can catch this regression next time.

I see three options: * Option 1 (change validate) - create a directory with tests that should be tested with the stage1 compiler. - In ./validate, add something like `make -C testsuite/tests/stage1-tests stage=1` (The full command would also include: `$MAKE_TEST_TARGET $BINDIST $TEST_VERBOSITY THREADS=$threads SUMMARY_FILE=...)` - Make sure the grepping for results in testsuite_summary.txt still does the right thing (bit fiddly) - Minor point: define target synonyms `fasttest` and `slowtest` in `testsuite/Makefile` and `testsuite/mk/test.mk`) * Option 2 (driver support) - add a new setup function to testsuite/driver/testlib.py: something like `def stage(n)` or `def stage1()` - assign the `STAGE1_GHC` variable from testsuite/mk/boilerplate.mk should to a new option config.stage1 (add `--config 'stage1=$(call quote_path,$(STAGE1_GHC))'` to RUNTEST_OPTS in testsuite/mk/test.mk, and change testsuite/driver/runtests.py and testsuite/driver/testglobals.py. - add a `compiler` field to TestOptions (testsuite/driver/testglobals.py). By default it should contain config.compiler (do so in `def test` in testsuite/driver/testlib.py, not sure..) - the setup function `stage1()` sets opts.compiler to config.stage1, but only when the stage1 compiler is available. When TEST_HC is specified or when TEST_HC is implied to be an installed compiler, STAGE1_GHC won't be defined. - change all uses of config.compiler to opts.compiler (grep also for '{compiler}'). * Option 3 (Makefile) - define the test in a Makefile. Refer to `STAGE1_GHC` instead of `TEST_HC`. Skip if empty. The drawback of option 1 is that a failing validate might confuse GHC developers, because they can't reproduce the test failure when running the test locally (they'd have to specify make stage=1, which isn't obvious). Many questions on IRC/Phabricator/mail. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:21 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: new Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D876 Wiki Page: | -------------------------------------+------------------------------------- Comment (by osa1): As far as I can see WAY only effects the arguments passed to GHC, so it doesn't help unless we do some refactoring in the test driver, and the test driver is ... messy. Can we do this with less amount of work by adding a new field to `testglobals.TestOptions`, something like `stage`, and then in `testlib.simple_build()` we check the option and override `compiler` variable? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: patch Priority: high | Milestone: 8.0.1 Component: Template Haskell | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D876 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"bbfff2298d7ea7d0f4e590f8137f43a651e8f61d/ghc" bbfff229/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="bbfff2298d7ea7d0f4e590f8137f43a651e8f61d" Unconditionally handle TH known key names. Previously, we didn't add Template Haskell key names to the list of known uniques when building a stage 1 compiler. But with f16ddcee0c64a92ab911a7841a8cf64e3ac671fd we may refer to TH names even in stage 1, and this was causing uniques to not be setup properly. Signed-off-by: Edward Z. Yang Test Plan: validate and run stage1 test suite Reviewers: osa1, austin, bgamari Reviewed By: bgamari Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1520 GHC Trac Issues: #10382 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:25 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10382: Template Haskell (non-quasi) quotes should work with stage 1 compiler -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: closed Priority: high | Milestone: 8.0.1 Component: Template Haskell | Version: 7.11 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D876 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed * resolution: => fixed Comment: Merged to `ghc-8.0` as 745bdd88f9e4f9c85d46e84c58d6799bf71725b7. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10382#comment:27 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler