From b67ee6e861903abb04e9024d605dfc7b00922633 Mon Sep 17 00:00:00 2001
From: Artturin <Artturin@artturin.com>
Date: Sun, 6 Nov 2022 06:16:13 +0200
Subject: [PATCH 1/3] lib/trivial: fix 'error: cannot decode virtual path
 '/nix/store/virtual0000000000000000000000005-source''

happens on lazy-trees branch of Nix (NixOS/nix#6530)
---
 lib/trivial.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/trivial.nix b/lib/trivial.nix
index 5d4fad8266bc..8f2023caaf8e 100644
--- a/lib/trivial.nix
+++ b/lib/trivial.nix
@@ -213,8 +213,8 @@ rec {
     # Default value to return if revision can not be determined
     default:
     let
-      revisionFile = "${toString ./..}/.git-revision";
-      gitRepo      = "${toString ./..}/.git";
+      revisionFile = ./.. + "/.git-revision";
+      gitRepo      = ./.. + "/.git";
     in if lib.pathIsGitRepo gitRepo
        then lib.commitIdFromGitRepo gitRepo
        else if lib.pathExists revisionFile then lib.fileContents revisionFile

From 8c1b0192c5cf48e176bd4937787ba548e050395d Mon Sep 17 00:00:00 2001
From: Artturin <Artturin@artturin.com>
Date: Sun, 6 Nov 2022 06:32:22 +0200
Subject: [PATCH 2/3] lib/sources: remove 2 usages of toString on a path which
 will be read using fileContents

It gives a warning on the lazy-trees branch of Nix
(NixOS/nix#6530)

"warning: applying 'toString' to path '...' and then accessing it is deprecated, at '...'"

'else toString (/. + "${base}/${path}");' at line 183 may still cause a warning but i don't know how
to reach that codepath and test so im leaving it untouched

changing it to 'else /. + "${base}/${path}";'
caused this error
```
error: a string that refers to a store path cannot be appended to a path

       at /home/systems/nixpkgs/lib/sources.nix:183:20:

          182|               then path
          183|               else /. + "${base}/${path}";
             |                    ^
          184|         in if pathIsRegularFile path
```
---
 lib/sources.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/sources.nix b/lib/sources.nix
index cec395c9bb18..51836696cf10 100644
--- a/lib/sources.nix
+++ b/lib/sources.nix
@@ -175,8 +175,8 @@ let
   */
   commitIdFromGitRepo =
     let readCommitFromFile = file: path:
-        let fileName       = toString path + "/" + file;
-            packedRefsName = toString path + "/packed-refs";
+        let fileName       = path + "/${file}";
+            packedRefsName = path + "/packed-refs";
             absolutePath   = base: path:
               if lib.hasPrefix "/" path
               then path

From ec8f8f69bd57b9dfd24ed56ef8f3c53c9ee5f453 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Mon, 7 Nov 2022 12:52:13 +0100
Subject: [PATCH 3/3] lib/sources: Make pathIsGitRepo not evaluate toString
 path

This requires us to avoid the `tryEval` + `throw` combination,
because throw is strict in its error message, and we don't want
to drop our single clue when `commitIdFromGitRepo` is used
incorrectly.
---
 lib/sources.nix | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/lib/sources.nix b/lib/sources.nix
index 51836696cf10..9db3d2329542 100644
--- a/lib/sources.nix
+++ b/lib/sources.nix
@@ -166,14 +166,25 @@ let
       in type == "directory" || lib.any (ext: lib.hasSuffix ext base) exts;
     in cleanSourceWith { inherit filter src; };
 
-  pathIsGitRepo = path: (tryEval (commitIdFromGitRepo path)).success;
+  pathIsGitRepo = path: (commitIdFromGitRepoOrError path)?value;
 
   /*
     Get the commit id of a git repo.
 
     Example: commitIdFromGitRepo <nixpkgs/.git>
   */
-  commitIdFromGitRepo =
+  commitIdFromGitRepo = path:
+    let commitIdOrError = commitIdFromGitRepoOrError path;
+    in commitIdOrError.value or (throw commitIdOrError.error);
+
+  /*
+    Get the commit id of a git repo.
+
+    Returns `{ value = commitHash }` or `{ error = "... message ..." }`.
+
+    Example: commitIdFromGitRepo <nixpkgs/.git>
+  */
+  commitIdFromGitRepoOrError =
     let readCommitFromFile = file: path:
         let fileName       = path + "/${file}";
             packedRefsName = path + "/packed-refs";
@@ -186,7 +197,7 @@ let
            then
              let m   = match "^gitdir: (.*)$" (lib.fileContents path);
              in if m == null
-                then throw ("File contains no gitdir reference: " + path)
+                then { error = "File contains no gitdir reference: " + path; }
                 else
                   let gitDir      = absolutePath (dirOf path) (lib.head m);
                       commonDir'' = if pathIsRegularFile "${gitDir}/commondir"
@@ -204,7 +215,7 @@ let
              let fileContent = lib.fileContents fileName;
                  matchRef    = match "^ref: (.*)$" fileContent;
              in if  matchRef == null
-                then fileContent
+                then { value = fileContent; }
                 else readCommitFromFile (lib.head matchRef) path
 
            else if pathIsRegularFile packedRefsName
@@ -218,10 +229,10 @@ let
                  # https://github.com/NixOS/nix/issues/2147#issuecomment-659868795
                  refs = filter isRef (split "\n" fileContent);
              in if refs == []
-                then throw ("Could not find " + file + " in " + packedRefsName)
-                else lib.head (matchRef (lib.head refs))
+                then { error = "Could not find " + file + " in " + packedRefsName; }
+                else { value = lib.head (matchRef (lib.head refs)); }
 
-           else throw ("Not a .git directory: " + path);
+           else { error = "Not a .git directory: " + toString path; };
     in readCommitFromFile "HEAD";
 
   pathHasContext = builtins.hasContext or (lib.hasPrefix storeDir);