digitalmars.D - Huge improvement in error messages in recent dmd
- mipri (52/52) Dec 11 2019 Consider the following code with an error:
- Meta (4/56) Dec 11 2019 Huh, I thought I was keeping up to date with the stuff in every
- Les De Ridder (4/13) Dec 12 2019 I agree, this is easily one of the most significant user
Consider the following code with an error:
import std;
void main() {
auto pts = Array!(int[])([0, 0], [5, 5], [0, 1], [0, 2]);
multiSort!("a[0] < b[0]", "a[1] < b[1]",
SwapStrategy.unstable)(pts);
}
The latest version of dmd that's packaged with Fedora is
2.086.1. Of this code it says:
./x266.d(5): Error: template
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort cannot deduce function from
argument types !()(Array!(int[])), candidates are:
/usr/include/dmd/phobos/std/algorithm/sorting.d(1463):
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort(Range)(Range r) if
(validPredicates!(ElementType!Range, less) &&
hasSwappableElements!Range)
The nightly I have is v2.089.1-beta.1, and it says:
x266.d(5): Error: template std.algorithm.sorting.multiSort!("a[0]
< b[0]", "a[1] < b[1]", cast(SwapStrategy)0).multiSort cannot
deduce function from argument types !()(Array!(int[])),
candidates are:
/edit/nightly/dmd2/linux/bin64/../../src/phobos/std/algorithm/sorting.d(1466):
multiSort(Range)(Range r)
with Range = Array!(int[])
must satisfy the following constraint:
hasSwappableElements!Range
Which is a huge, huge improvement! The problem is that
Array!(Point) doesn't satisfy hasSwappableElements.
I saw that this was also in the v2.089.0 compiler, and so
checked the blog for announcements back to v2.087, and none of
them showed how much better the error messages got. This should
be highlighted. I don't normally care that much about staying
exactly up-to-date with compilers, but I'd sure have upgraded
earlier for this.
A slightly strange thing is that rdmd's error messages are
even friendlier (v2.089.0):
./x266.d(5): Error: template
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort cannot deduce function from
argument types !()(Array!(int[])), candidates are:
/edit/latest/dmd2/linux/bin64/../../src/phobos/std/algorithm/sorting.d(1466):
multiSort(Range)(Range r)
with Range = Array!(int[])
whose parameters have the following constraints:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
validPredicates!(ElementType!Range, less)
> hasSwappableElements!Range
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tip: not satisfied constraints are marked with >
wow!
Dec 11 2019
Meta <jared771 gmail.com>
On Thursday, 12 December 2019 at 00:39:15 UTC, mipri wrote:
Consider the following code with an error:
import std;
void main() {
auto pts = Array!(int[])([0, 0], [5, 5], [0, 1], [0, 2]);
multiSort!("a[0] < b[0]", "a[1] < b[1]",
SwapStrategy.unstable)(pts);
}
The latest version of dmd that's packaged with Fedora is
2.086.1. Of this code it says:
./x266.d(5): Error: template
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort cannot deduce function from
argument types !()(Array!(int[])), candidates are:
/usr/include/dmd/phobos/std/algorithm/sorting.d(1463):
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort(Range)(Range r) if
(validPredicates!(ElementType!Range, less) &&
hasSwappableElements!Range)
The nightly I have is v2.089.1-beta.1, and it says:
x266.d(5): Error: template
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort cannot deduce function from
argument types !()(Array!(int[])), candidates are:
/edit/nightly/dmd2/linux/bin64/../../src/phobos/std/algorithm/sorting.d(1466):
multiSort(Range)(Range r)
with Range = Array!(int[])
must satisfy the following constraint:
hasSwappableElements!Range
Which is a huge, huge improvement! The problem is that
Array!(Point) doesn't satisfy hasSwappableElements.
I saw that this was also in the v2.089.0 compiler, and so
checked the blog for announcements back to v2.087, and none of
them showed how much better the error messages got. This should
be highlighted. I don't normally care that much about staying
exactly up-to-date with compilers, but I'd sure have upgraded
earlier for this.
A slightly strange thing is that rdmd's error messages are
even friendlier (v2.089.0):
./x266.d(5): Error: template
std.algorithm.sorting.multiSort!("a[0] < b[0]", "a[1] < b[1]",
cast(SwapStrategy)0).multiSort cannot deduce function from
argument types !()(Array!(int[])), candidates are:
/edit/latest/dmd2/linux/bin64/../../src/phobos/std/algorithm/sorting.d(1466):
multiSort(Range)(Range r)
with Range = Array!(int[])
whose parameters have the following constraints:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
validPredicates!(ElementType!Range, less)
> hasSwappableElements!Range
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tip: not satisfied constraints are marked with >
wow!
Huh, I thought I was keeping up to date with the stuff in every
new release, but apparently not, as I had no idea that template
constraint function error messages had been improved.
Dec 11 2019
On Thursday, 12 December 2019 at 00:39:15 UTC, mipri wrote:[...] Which is a huge, huge improvement! The problem is that Array!(Point) doesn't satisfy hasSwappableElements. I saw that this was also in the v2.089.0 compiler, and so checked the blog for announcements back to v2.087, and none of them showed how much better the error messages got. This should be highlighted. I don't normally care that much about staying exactly up-to-date with compilers, but I'd sure have upgraded earlier for this.I agree, this is easily one of the most significant user experience improvements in years.
Dec 12 2019