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| author | Ryan Scott <ryan.gl.scott@gmail.com> | 2018-05-13 18:36:23 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-05-13 22:22:43 -0400 |
| commit | 21e1a00c0ccf3072ccc04cd1acfc541c141189d2 (patch) | |
| tree | 6730896263197984b0466c22b84ab007401d775a /testsuite/tests/th/all.T | |
| parent | bf6cad8b86ee34ed5aa5fa0e295304b51f2a2324 (diff) | |
| download | haskell-21e1a00c0ccf3072ccc04cd1acfc541c141189d2.tar.gz | |
Fix #14875 by introducing PprPrec, and using it
Trying to determine when to insert parentheses during TH
conversion is a bit of a mess. There is an assortment of functions
that try to detect this, such as:
* `hsExprNeedsParens`
* `isCompoundHsType`
* `hsPatNeedsParens`
* `isCompoundPat`
* etc.
To make things worse, each of them have slightly different semantics.
Plus, they don't work well in the presence of explicit type
signatures, as #14875 demonstrates.
All of these problems can be alleviated with the use of an explicit
precedence argument (much like what `showsPrec` currently does). To
accomplish this, I introduce a new `PprPrec` data type, and define
standard predences for things like function application, infix
operators, function arrows, and explicit type signatures (that last
one is new). I then added `PprPrec` arguments to the various
`-NeedsParens` functions, and use them to make smarter decisions
about when things need to be parenthesized.
A nice side effect is that functions like `isCompoundHsType` are
now completely unneeded, since they're simply aliases for
`hsTypeNeedsParens appPrec`. As a result, I did a bit of refactoring
to remove these sorts of functions. I also did a pass over various
utility functions in GHC for constructing AST forms and used more
appropriate precedences where convenient.
Along the way, I also ripped out the existing `TyPrec`
data type (which was tailor-made for pretty-printing `Type`s) and
replaced it with `PprPrec` for consistency.
Test Plan: make test TEST=T14875
Reviewers: alanz, goldfire, bgamari
Reviewed By: bgamari
Subscribers: rwbarton, thomie, carter
GHC Trac Issues: #14875
Differential Revision: https://phabricator.haskell.org/D4688
Diffstat (limited to 'testsuite/tests/th/all.T')
| -rw-r--r-- | testsuite/tests/th/all.T | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/testsuite/tests/th/all.T b/testsuite/tests/th/all.T index 2b6e517697..4169d7e202 100644 --- a/testsuite/tests/th/all.T +++ b/testsuite/tests/th/all.T @@ -407,6 +407,7 @@ test('T14869', normal, compile, test('T14888', normal, compile, ['-v0 -ddump-splices -dsuppress-uniques ' + config.ghc_th_way_flags]) test('T14298', normal, compile_and_run, ['-v0']) +test('T14875', normal, compile, ['-v0 -ddump-splices -dsuppress-uniques']) test('T14885a', normal, compile, ['']) test('T14885b', normal, compile, ['']) test('T14885c', normal, compile, ['']) |