-
e34cb6da
by Adam Gundry at 2026-03-20T12:20:00-04:00
ghci: Mention active language edition in startup banner
Per GHC proposal 632, this makes the GHCi startup banner include
the active language edition, plus an indication of whether this
was the default (as opposed to being explicitly selected via an
option such as `-XGHC2024`). For example:
```
$ ghci
GHCi, version 9.14.1: https://www.haskell.org/ghc/ :? for help
Using default language edition: GHC2024
ghci>
```
Fixes #26037.
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52c3e6ba
by sheaf at 2026-03-20T12:21:09-04:00
Improve incomplete record selector warnings
This commit stops GHC from emitting spurious incomplete record selector
warnings for bare selectors/projections such as .fld
There are two places we currently emit incomplete record selector
warnings:
1. In the desugarer, when we see a record selector or an occurrence
of 'getField'. Here, we can use pattern matching information to
ensure we don't give false positives.
2. In the typechecker, which might sometimes give false positives but
can emit warnings in cases that the pattern match checker would
otherwise miss.
This is explained in Note [Detecting incomplete record selectors]
in GHC.HsToCore.Pmc.
Now, we obviously don't want to emit the same error twice, and generally
we prefer (1), as those messages contain fewer false positives. So we
suppress (2) when we are sure we are going to emit (1); the logic for
doing so is in GHC.Tc.Instance.Class.warnIncompleteRecSel,
and works by looking at the CtOrigin.
Now, the issue was that this logic handled explicit record selectors as
well as overloaded record field selectors such as "x.r" (which turns
into a simple GetFieldOrigin CtOrigin), but it didn't properly handle
record projectors like ".fld" or ".fld1.fld2" (which result in other
CtOrigins such as 'RecordFieldProjectionOrigin').
To solve this problem, we re-use the 'isHasFieldOrigin' introduced in
fbdc623a (slightly adjusted).
On the way, we also had to update the desugarer with special handling
for the 'ExpandedThingTc' case in 'ds_app', to make sure that
'ds_app_var' sees all the type arguments to 'getField' in order for it
to indeed emit warnings like in (1).
Fixes #26686
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309d7e87
by Cheng Shao at 2026-03-20T12:21:53-04:00
rts: opportunistically grow the MutableByteArray# in-place in resizeMutableByteArray#
Following !15234, this patch improves `resizeMutableByteArray#` memory
efficiency by growing the `MutableByteArray#` in-place if possible,
addressing an old todo comment here. Also adds a new test case
`resizeMutableByteArrayInPlace` that stresses this behavior.
-
7d4ef162
by Matthew Craven at 2026-03-20T12:22:47-04:00
Change representation of floating point literals
This commit changes the representation of floating point literals
throughough the compiler, in particular in Core and Cmm.
The Rational type is deficient for this purpose, dealing poorly
with NaN, +/-Infinity, and negative zero. Instead, the new module
GHC.Types.Literal.Floating uses the host Float/Double type to represent
NaNs, infinities and negative zero. It also contains a Rational
constructor, for the benefit of -fexcess-precision.
Other changes:
- Remove Note [negative zero] and related code
This also removes the restrictions on constant-folding of division
by zero, and should make any problems with NaN/Infinity more obvious.
- Use -0.0 as the additive identity for Core constant folding rules
for floating-point addition, fixing #21227.
- Manual worker-wrapper for GHC.Float.rationalToDouble. This is
intended to prevent the compiler's WW on this function from
interfering with constant-folding. This change means that we now
avoid allocating a box for the result of a 'realToFrac' call in
T10359.
- Combine floatDecodeOp and doubleDecodeOp.
This change also fixes a bug in doubleDecodeOp wherein it
would incorrectly produce an Int# instead of an Int64#
literal for the mantissa component with 64-bit targets.
- Use Float/Double for assembly immediates, and update the X86 and
PowerPC backends to properly handle special values such as NaN and
infinity.
- Allow 'rational_to' to handle zero denominators, fixing a
TODO in GHC.Core.Opt.ConstantFold.
Fixes #8364 #9811 #18897 #21227
Progress towards #26919
Metric Decrease:
T10359
Co-authored-by: sheaf <sam.derbyshire@gmail.com>
-------------------------
Metric Decrease:
T1969
T5321FD
-------------------------
-
80e2dd4f
by Zubin Duggal at 2026-03-20T12:23:33-04:00
compiler/ffi: Collapse void pointer chains in capi wrappers
New gcc/clang treat -Wincompatible-pointer-types as an error by
default. Since C only allows implicit conversion from void*, not void**,
capi wrappers for functions taking e.g. abstract** would fail to compile
when the Haskell type Ptr (Ptr Abstract) was naively translated to void**.
Collapse nested void pointers to a single void* when the pointee type
has no known C representation.
Fixes #26852
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1c50bd7b
by Luite Stegeman at 2026-03-20T12:24:37-04:00
Move some functions related to pointer tagging to a separate module
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bfd7aafd
by Luite Stegeman at 2026-03-20T12:24:37-04:00
Branchless unpacking for enumeration types
Change unpacking for enumeration types to go to Word8#/Word16#/Word#
directly instead of going through an intermediate unboxed sum. This
allows us to do a branchless conversion using DataToTag and TagToEnum.
Fixes #26970
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72b20fc0
by Luite Stegeman at 2026-03-20T12:25:30-04:00
bytecode: Carefully SLIDE off the end of a stack chunk
The SLIDE bytecode instruction was not checking for stack chunk
boundaries and could corrupt the stack underflow frame, leading
to crashes.
We add a check to use safe writes if we cross the chunk boundary
and also handle stack underflow if Sp is advanced past the underflow
frame.
fix #27001
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2e22b43c
by Cheng Shao at 2026-03-20T12:26:14-04:00
ghci: serialize BCOByteArray buffer directly when possible
This patch changes the `Binary` instances of `BCOByteArray` to
directly serialize the underlying buffer when possible, while also
taking into account the issue of host-dependent `Word` width. See
added comments and amended `Note [BCOByteArray serialization]` for
detailed explanation. Closes #27020.
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89d9ba37
by Sylvain Henry at 2026-03-20T12:27:34-04:00
JS: replace BigInt with Number arithmetic for 32/64-bit quot/rem (#23597)
Replace BigInt-based implementations of quotWord32, remWord32,
quotRemWord32, quotRem2Word32, quotWord64, remWord64, quotInt64, and
remInt64 with pure Number (double/integer) arithmetic to avoid the
overhead of BigInt promotion.
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ae4ddd60
by Sylvain Henry at 2026-03-20T12:28:28-04:00
Core: add constant-folding rules for Addr# eq/ne (#18032)
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3e767f98
by Matthew Pickering at 2026-03-20T12:29:11-04:00
Use OsPath rather than FilePath in Downsweep cache
This gets us one step closure to uniformly using `OsPath` in the
compiler.
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2c57de29
by Cheng Shao at 2026-03-20T12:29:55-04:00
hadrian: fix ghc-in-ghci flavour stage0 shared libraries
This patch fixes missing stage0 shared libraries in hadrian
ghc-in-ghci flavour, which was accidentally dropped in
669d09f950a6e88b903d9fd8a7571531774d4d5d and resulted in a regression
in HLS support on linux/macos. Fixes #27057.
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5b1be555
by Sylvain Henry at 2026-03-20T12:30:48-04:00
JS: install rts/Types.h header file (#27033)
It was an omission, making HsFFI.h not usable with GHC using the JS
backend.
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b883f08f
by Cheng Shao at 2026-03-20T12:31:33-04:00
hadrian: don't compile RTS with -Winline
This patch removes `-Winline` from cflags when compiling the RTS,
given that:
1. It generates a huge pile of spam and hurts developer experience
2. Whether inlining happens is highly dependent on toolchains,
flavours, etc, and it's not really an issue to fix if inlining
doesn't happen; it's a hint to the C compiler anyway.
Fixes #27060.
-
333387d6
by Cheng Shao at 2026-03-20T12:31:33-04:00
hadrian: compile libffi-clib with -Wno-deprecated-declarations
This patch adds `-Wno-deprecated-declarations` to cflags of
`libffi-clib`, given that it produces noise at compile-time that
aren't really our issue to fix anyway, it's from vendored libffi
source code.
-
67c47771
by Rodrigo Mesquita at 2026-03-20T12:32:17-04:00
Expose decodeStackWithIpe from ghc-experimental
This decoding is useful to the debugger and it wasn't originally
exported as an oversight.
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0cb532cd
by Cheng Shao at 2026-03-20T20:02:36+00:00
rts: fix -Wcompare-distinct-pointer-types errors
This commit fixes `-Wcompare-distinct-pointer-types` errors in the RTS
which should have been caught by the `validate` flavour but was
warnings in CI due to the recent `+werror` regression.
-
af543550
by Cheng Shao at 2026-03-20T20:02:36+00:00
ghc-internal: fix unused imports
This commit fixes unused imports in `ghc-internal` which should have
been caught by the `validate` flavour but was warnings in CI due to
the recent `+werror` regression. Fixes #27059.
-
f14f93c8
by Cheng Shao at 2026-03-20T20:02:36+00:00
compiler: fix unused imports in GHC.Tc.Types.Origin
This commit fixes unused imports in `GHC.Tc.Types.Origin` which should
have been caught by the `validate` flavour but was warnings in CI due
to the recent `+werror` regression. Fixes #27059.
-
13268343
by Cheng Shao at 2026-03-20T20:02:36+00:00
hadrian: fix missing +werror in validate flavour
This patch fixes missing `+werror` in validate flavour, which was an
oversight in bb3a2ba1eefadf0b2ef4f39b31337a23eec67f29. Fixes #27066.