lunaphied/lix
0
0
Fork 0
forked from lix-project/lix
Code Pull requests Activity

Merge pull request #5286 from ilkecan/add-a-warning-to-filterSource

Browse source 
Warn about the usage of filterSource with Nix store paths
This commit is contained in:
Eelco Dolstra 2021-10-06 21:02:39 +02:00 committed by GitHub
parent dcb3bc614c a4a6ef4fb2
commit 53e4794289
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 15 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

17
src/libexpr/primops.cc
View file

@ -414,7 +414,7 @@ static RegisterPrimOp primop_isNull({
Return `true` if *e* evaluates to `null`, and `false` otherwise.
> **Warning**
>
>
> This function is *deprecated*; just write `e == null` instead.
)",
.fun = prim_isNull,
@ -1923,6 +1923,19 @@ static RegisterPrimOp primop_filterSource({
.name = "__filterSource",
.args = {"e1", "e2"},
.doc = R"(
> **Warning**
>
> `filterSource` should not be used to filter store paths. Since
> `filterSource` uses the name of the input directory while naming
> the output directory, doing so will produce a directory name in
> the form of `<hash2>-<hash>-<name>`, where `<hash>-<name>` is
> the name of the input directory. Since `<hash>` depends on the
> unfiltered directory, the name of the output directory will
> indirectly depend on files that are filtered out by the
> function. This will trigger a rebuild even when a filtered out
> file is changed. Use `builtins.path` instead, which allows
> specifying the name of the output directory.
This function allows you to copy sources into the Nix store while
filtering certain files. For instance, suppose that you want to use
the directory `source-dir` as an input to a Nix expression, e.g.
@ -2523,7 +2536,7 @@ static RegisterPrimOp primop_tail({
the argument isn’t a list or is an empty list.
> **Warning**
>
>
> This function should generally be avoided since it's inefficient:
> unlike Haskell's `tail`, it takes O(n) time, so recursing over a
> list by repeatedly calling `tail` takes O(n^2) time.