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lib.path: remove assertMsg usage

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assertMsg sends our error message through a function call, even if the
error condition doesn't trigger. This requires a lot of thunk allocation
that can be easily avoided.
This commit is contained in:
Eman Resu
2026-05-26 13:22:54 -04:00
parent a017ab10eb
commit 4ff2645579
1 changed files with 51 additions and 38 deletions
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lib/path/default.nix
+51 -38
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@@ -32,10 +32,6 @@ let
substring
;
inherit (lib.asserts)
assertMsg
;
inherit (lib.path.subpath)
isValid
;
@@ -238,11 +234,14 @@ in
path:
# The subpath string to append
subpath:
assert assertMsg (isPath path)
"lib.path.append: The first argument is of type ${builtins.typeOf path}, but a path was expected";
assert assertMsg (isValid subpath) ''
lib.path.append: Second argument is not a valid subpath string:
${subpathInvalidReason subpath}'';
assert
isPath path
|| throw "lib.path.append: The first argument is of type ${builtins.typeOf path}, but a path was expected";
assert
isValid subpath
|| throw ''
lib.path.append: Second argument is not a valid subpath string:
${subpathInvalidReason subpath}'';
path + ("/" + subpath);
/**
@@ -285,21 +284,25 @@ in
*/
hasPrefix =
path1:
assert assertMsg (isPath path1)
"lib.path.hasPrefix: First argument is of type ${typeOf path1}, but a path was expected";
assert
isPath path1
|| throw "lib.path.hasPrefix: First argument is of type ${typeOf path1}, but a path was expected";
let
path1Deconstructed = deconstructPath path1;
in
path2:
assert assertMsg (isPath path2)
"lib.path.hasPrefix: Second argument is of type ${typeOf path2}, but a path was expected";
assert
isPath path2
|| throw "lib.path.hasPrefix: Second argument is of type ${typeOf path2}, but a path was expected";
let
path2Deconstructed = deconstructPath path2;
in
assert assertMsg (path1Deconstructed.root == path2Deconstructed.root) ''
lib.path.hasPrefix: Filesystem roots must be the same for both paths, but paths with different roots were given:
first argument: "${toString path1}" with root "${toString path1Deconstructed.root}"
second argument: "${toString path2}" with root "${toString path2Deconstructed.root}"'';
assert
path1Deconstructed.root == path2Deconstructed.root
|| throw ''
lib.path.hasPrefix: Filesystem roots must be the same for both paths, but paths with different roots were given:
first argument: "${toString path1}" with root "${toString path1Deconstructed.root}"
second argument: "${toString path2}" with root "${toString path2Deconstructed.root}"'';
take (length path1Deconstructed.components) path2Deconstructed.components
== path1Deconstructed.components;
@@ -344,15 +347,17 @@ in
*/
removePrefix =
path1:
assert assertMsg (isPath path1)
"lib.path.removePrefix: First argument is of type ${typeOf path1}, but a path was expected.";
assert
isPath path1
|| throw "lib.path.removePrefix: First argument is of type ${typeOf path1}, but a path was expected.";
let
path1Deconstructed = deconstructPath path1;
path1Length = length path1Deconstructed.components;
in
path2:
assert assertMsg (isPath path2)
"lib.path.removePrefix: Second argument is of type ${typeOf path2}, but a path was expected.";
assert
isPath path2
|| throw "lib.path.removePrefix: Second argument is of type ${typeOf path2}, but a path was expected.";
let
path2Deconstructed = deconstructPath path2;
success = take path1Length path2Deconstructed.components == path1Deconstructed.components;
@@ -362,10 +367,12 @@ in
else
throw ''lib.path.removePrefix: The first path argument "${toString path1}" is not a component-wise prefix of the second path argument "${toString path2}".'';
in
assert assertMsg (path1Deconstructed.root == path2Deconstructed.root) ''
lib.path.removePrefix: Filesystem roots must be the same for both paths, but paths with different roots were given:
first argument: "${toString path1}" with root "${toString path1Deconstructed.root}"
second argument: "${toString path2}" with root "${toString path2Deconstructed.root}"'';
assert
path1Deconstructed.root == path2Deconstructed.root
|| throw ''
lib.path.removePrefix: Filesystem roots must be the same for both paths, but paths with different roots were given:
first argument: "${toString path1}" with root "${toString path1Deconstructed.root}"
second argument: "${toString path2}" with root "${toString path2Deconstructed.root}"'';
joinRelPath components;
/**
@@ -422,8 +429,9 @@ in
splitRoot =
# The path to split the root off of
path:
assert assertMsg (isPath path)
"lib.path.splitRoot: Argument is of type ${typeOf path}, but a path was expected";
assert
isPath path
|| throw "lib.path.splitRoot: Argument is of type ${typeOf path}, but a path was expected";
let
deconstructed = deconstructPath path;
in
@@ -494,14 +502,15 @@ in
let
deconstructed = deconstructPath path;
in
assert assertMsg (isPath path)
"lib.path.hasStorePathPrefix: Argument is of type ${typeOf path}, but a path was expected";
assert assertMsg
assert
isPath path
|| throw "lib.path.hasStorePathPrefix: Argument is of type ${typeOf path}, but a path was expected";
assert
# This function likely breaks or needs adjustment if used with other filesystem roots, if they ever get implemented.
# Let's try to error nicely in such a case, though it's unclear how an implementation would work even and whether this could be detected.
# See also https://github.com/NixOS/nix/pull/6530#discussion_r1422843117
(deconstructed.root == /. && toString deconstructed.root == "/")
"lib.path.hasStorePathPrefix: Argument has a filesystem root (${toString deconstructed.root}) that's not /, which is currently not supported.";
deconstructed.root == /. && toString deconstructed.root == "/"
|| throw "lib.path.hasStorePathPrefix: Argument has a filesystem root (${toString deconstructed.root}) that's not /, which is currently not supported.";
componentsHaveStorePathPrefix deconstructed.components;
/**
@@ -702,9 +711,11 @@ in
subpath.components =
# The subpath string to split into components
subpath:
assert assertMsg (isValid subpath) ''
lib.path.subpath.components: Argument is not a valid subpath string:
${subpathInvalidReason subpath}'';
assert
isValid subpath
|| throw ''
lib.path.subpath.components: Argument is not a valid subpath string:
${subpathInvalidReason subpath}'';
splitRelPath subpath;
/**
@@ -799,9 +810,11 @@ in
subpath.normalise =
# The subpath string to normalise
subpath:
assert assertMsg (isValid subpath) ''
lib.path.subpath.normalise: Argument is not a valid subpath string:
${subpathInvalidReason subpath}'';
assert
isValid subpath
|| throw ''
lib.path.subpath.normalise: Argument is not a valid subpath string:
${subpathInvalidReason subpath}'';
joinRelPath (splitRelPath subpath);
}