GitLab

Alan Zimmerman pushed to branch wip/az/ghc-cpp at Glasgow Haskell Compiler / GHC

Commits:

ce616f49

by Simon Peyton Jones at 2025-04-27T21:10:25+01:00

Fix infelicities in the Specialiser

On the way to #23109 (unary classes) I discovered some infelicities
(or maybe tiny bugs, I forget) in the type-class specialiser.

I also tripped over #25965, an outright bug in the rule matcher

Specifically:

* Refactor: I enhanced `wantCallsFor`, whih previously always said
`True`, to discard calls of class-ops, data constructors etc.  This is
a bit more efficient; and it means we don't need to worry about
filtering them out later.

* Fix: I tidied up some tricky logic that eliminated redundant
  specialisations.  It wasn't working correctly.  See the expanded
  Note [Specialisations already covered], and
  (MP3) in Note [Specialising polymorphic dictionaries].

  See also the new top-level `alreadyCovered`
  function, which now goes via `GHC.Core.Rules.ruleLhsIsMoreSpecific`

  I also added a useful Note [The (CI-KEY) invariant]

* Fix #25965: fixed a tricky bug in the `go_fam_fam` in
  `GHC.Core.Unify.uVarOrFam`, which allows matching to succeed
  without binding all type varibles.

  I enhanced Note [Apartness and type families] some more

* #25703. This ticket "just works" with -fpolymorphic-specialisation;
  but I was surprised that it worked! In this MR I added documentation
  to Note [Interesting dictionary arguments] to explain; and tests to
  ensure it stays fixed.

22d11fa8

by Simon Peyton Jones at 2025-04-28T18:05:19-04:00

Track rewriter sets more accurately in constraint solving

The key change, which fixed #25440, is to call `recordRewriter` in
GHC.Tc.Solver.Rewrite.rewrite_exact_fam_app.  This missing call meant
that we were secretly rewriting a Wanted with a Wanted, but not really
noticing; and that led to a very bad error message, as you can see
in the ticket.

But of course that led me into rabbit hole of other refactoring around
the RewriteSet code:

* Improve Notes [Wanteds rewrite Wanteds]

* Zonk the RewriterSet in `zonkCtEvidence` rather than only in GHC.Tc.Errors.
  This is tidier anyway (e.g. de-clutters debug output), and helps with the
  next point.

* In GHC.Tc.Solver.Equality.inertsCanDischarge, don't replace a constraint
  with no rewriters with an equal constraint that has many. See
  See (CE4) in Note [Combining equalities]

* Move zonkRewriterSet and friends from GHC.Tc.Zonk.Type into
  GHC.Tc.Zonk.TcType, where they properly belong.

A handful of tests get better error messages.

For some reason T24984 gets 12% less compiler allocation -- good

Metric Decrease:
    T24984

6467d61e

by Brandon Chinn at 2025-04-29T18:36:03-04:00

Fix lexing "\^\" (#25937)

This broke in the refactor in !13128, where the old code parsed escape
codes and collapsed string gaps at the same time, but the new code
collapsed gaps first, then resolved escape codes. The new code used a
naive heuristic to skip escaped backslashes, but didn't account for
"\^\".

99868a86
by Jens Petersen at 2025-04-29T18:36:44-04:00
```
hadrian: default selftest to disabled
```

aba2a4a5

by Zubin Duggal at 2025-04-30T06:35:59-04:00

get-win32-tarballs.py: List tarball files to be downloaded if we cannot find them

Fixes #25929

d99a617b

by Ben Gamari at 2025-04-30T06:36:40-04:00

Move Data ModuleName instance to Language.Haskell.Syntax.Module.Name

Fixes #25968.

b5e557d8

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

GHC-CPP: first rough proof of concept

Processes

     #define FOO
     #ifdef FOO
     x = 1
     #endif

Into

    [ITcppIgnored [L loc ITcppDefine]
    ,ITcppIgnored [L loc ITcppIfdef]
    ,ITvarid "x"
    ,ITequal
    ,ITinteger (IL {il_text = SourceText "1", il_neg = False, il_value = 1})
    ,ITcppIgnored [L loc ITcppEndif]
    ,ITeof]

In time, ITcppIgnored will be pushed into a comment

8571387c

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Tidy up before re-visiting the continuation mechanic

92273c0f

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Switch preprocessor to continuation passing style

Proof of concept, needs tidying up

d8c87361
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Small cleanup
```
30a1a4e5
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Get rid of some cruft
```

7dd5d77c

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Starting to integrate.

Need to get the pragma recognised and set

b44b17cf

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Make cppTokens extend to end of line, and process CPP comments

71d19727
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Remove unused ITcppDefined
```

c326a944

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Allow spaces between # and keyword for preprocessor directive

9dcd821c

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Process CPP continuation lines

They are emited as separate ITcppContinue tokens.
Perhaps the processing should be more like a comment, and keep on
going to the end.
BUT, the last line needs to be slurped as a whole.

873d3c9b

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Accumulate CPP continuations, process when ready

Can be simplified further, we only need one CPP token

1d604a35

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Simplify Lexer interface. Only ITcpp

We transfer directive lines through it, then parse them from scratch
in the preprocessor.

bcd77e8b

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Deal with directive on last line, with no trailing \n

55f1056a
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Start parsing and processing the directives
```
8f2079a7
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Prepare for processing include files
```

2407cbed

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Move PpState into PreProcess

And initParserState, initPragState too

8a9008c4

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Process nested include files

Also move PpState out of Lexer.x, so it is easy to evolve it in a ghci
session, loading utils/check-cpp/Main.hs

24e47f5d
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Split into separate files
```

ace37ecb

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Starting on expression parser.

But it hangs. Time for Text.Parsec.Expr

d7c05912

by Alan Zimmerman at 2025-04-30T18:27:18+01:00

Start integrating the ghc-cpp work

From https://github.com/alanz/ghc-cpp

c96e142b
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
WIP
```
c4cc4cec
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Fixup after rebase
```
1728a5f9
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
WIP
```
86eb1e35
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Fixup after rebase, including all tests pass
```
091892a4
by Alan Zimmerman at 2025-04-30T18:27:18+01:00
```
Change pragma usage to GHC_CPP from GhcCPP
```
fc6e9524
by Alan Zimmerman at 2025-04-30T18:27:19+01:00
```
Some comments
```
7e907713
by Alan Zimmerman at 2025-04-30T18:27:19+01:00
```
Reformat
```
9844268f
by Alan Zimmerman at 2025-04-30T18:27:19+01:00
```
Delete unused file
```
714dec3b
by Alan Zimmerman at 2025-04-30T18:27:19+01:00
```
Rename module Parse to ParsePP
```
6c09c72a
by Alan Zimmerman at 2025-04-30T18:27:19+01:00
```
Clarify naming in the parser
```

90f621b0