Merge commit '84d74ae9c9cbed73274b8e4e00be14688ffc93fe'

1 files changed, 25 insertions, 8 deletions

diff --git a/nixpkgs/lib/strings.nix b/nixpkgs/lib/strings.nix
index 74e3eaa0722d..9fa9f023561e 100644
--- a/nixpkgs/lib/strings.nix
+++ b/nixpkgs/lib/strings.nix
@@ -612,6 +612,22 @@ rec {
   */
   fixedWidthNumber = width: n: fixedWidthString width "0" (toString n);
 
+  /* Convert a float to a string, but emit a warning when precision is lost
+     during the conversion
+
+     Example:
+       floatToString 0.000001
+       => "0.000001"
+       floatToString 0.0000001
+       => trace: warning: Imprecise conversion from float to string 0.000000
+          "0.000000"
+  */
+  floatToString = float: let
+    result = toString float;
+    precise = float == builtins.fromJSON result;
+  in if precise then result
+    else lib.warn "Imprecise conversion from float to string ${result}" result;
+
   /* Check whether a value can be coerced to a string */
   isCoercibleToString = x:
     builtins.elem (builtins.typeOf x) [ "path" "string" "null" "int" "float" "bool" ] ||
@@ -673,14 +689,15 @@ rec {
             "/prefix/nix-profiles-library-paths.patch"
             "/prefix/compose-search-path.patch" ]
   */
-  readPathsFromFile = rootPath: file:
-    let
-      lines = lib.splitString "\n" (builtins.readFile file);
-      removeComments = lib.filter (line: line != "" && !(lib.hasPrefix "#" line));
-      relativePaths = removeComments lines;
-      absolutePaths = builtins.map (path: rootPath + "/${path}") relativePaths;
-    in
-      absolutePaths;
+  readPathsFromFile = lib.warn "lib.readPathsFromFile is deprecated, use a list instead"
+    (rootPath: file:
+      let
+        lines = lib.splitString "\n" (builtins.readFile file);
+        removeComments = lib.filter (line: line != "" && !(lib.hasPrefix "#" line));
+        relativePaths = removeComments lines;
+        absolutePaths = builtins.map (path: rootPath + "/${path}") relativePaths;
+      in
+        absolutePaths);
 
   /* Read the contents of a file removing the trailing \n