Merge changes Ie29a8a89,I873eedcf into main

* changes:
  store: delete obsolete lsof-disabling code
  store: guess the URL of failing fixed-output derivations

6 files changed, 40 insertions, 19 deletions

diff --git a/doc/manual/rl-next/fod-failure-includes-url.md b/doc/manual/rl-next/fod-failure-includes-url.md
new file mode 100644
index 000000000..43179aa52
--- /dev/null
+++ b/doc/manual/rl-next/fod-failure-includes-url.md
@@ -0,0 +1,16 @@
+---
+synopsis: "Hash mismatch diagnostics for fixed-output derivations include the URL"
+cls: [1536]
+credits: [jade]
+category: Improvements
+---
+
+Now, when building fixed-output derivations, Lix will guess the URL that was used in the derivation using the `url` or `urls` properties in the derivation environment.
+This is a layering violation but making these diagnostics tractable when there are multiple instances of the `AAAA` hash is too significant of an improvement to pass it up.
+
+```
+error: hash mismatch in fixed-output derivation '/nix/store/sjfw324j4533lwnpmr5z4icpb85r63ai-x1.drv':
+        likely URL: https://meow.puppy.forge/puppy.tar.gz
+         specified: sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
+            got:    sha256-a1Qvp3FOOkWpL9kFHgugU1ok5UtRPSu+NwCZKbbaEro=
+```
diff --git a/doc/manual/src/contributing/testing.md b/doc/manual/src/contributing/testing.md
index 84836b891..b6b5318e0 100644
--- a/doc/manual/src/contributing/testing.md
+++ b/doc/manual/src/contributing/testing.md
@@ -433,9 +433,6 @@ I grepped `src/` for `get[eE]nv\("` to find the mentions in Lix code.
 - `NIX_PROFILE` - Selects which profile `nix-env` will operate on. Documented elsewhere.
 - `NIX_SSHOPTS` - Options passed to `ssh(1)` when using a ssh remote store.
   Incorrectly documented on `nix-copy-closure` which is *surely* not the only place they are used??
-- `_NIX_TEST_NO_LSOF` - Used on non-Linux, non-macOS platforms to disable using `lsof` when finding gc roots.
-
-  Since https://git.lix.systems/lix-project/lix/issues/156 was fixed, this should probably just be removed as it was a bad workaround for a macOS issue.
 - `_NIX_TEST_GC_SYNC_1` - Path to a pipe that is used to block the GC briefly to validate invariants from the test suite.
 - `_NIX_TEST_GC_SYNC_2` - Path to a pipe that is used to block the GC briefly to validate invariants from the test suite.
 - `_NIX_TEST_FREE_SPACE_FILE` - Path to a file containing a decimal number with the free space that the GC is to believe it has.
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index 968f669ec..1dd2ad8aa 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2546,9 +2546,12 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
                     /* Throw an error after registering the path as
                        valid. */
                     worker.hashMismatch = true;
+                    // XXX: shameless layering violation hack that makes the hash mismatch error at least not utterly worthless
+                    auto guessedUrl = getOr(drv->env, "urls", getOr(drv->env, "url", "(unknown)"));
                     delayedException = std::make_exception_ptr(
-                        BuildError("hash mismatch in fixed-output derivation '%s':\n  specified: %s\n     got:    %s",
+                        BuildError("hash mismatch in fixed-output derivation '%s':\n likely URL: %s\n  specified: %s\n     got:    %s",
                             worker.store.printStorePath(drvPath),
+                            guessedUrl,
                             wanted.to_string(SRI, true),
                             got.to_string(SRI, true)));
                 }
diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index d58e3c8eb..02234d404 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -321,22 +321,20 @@ Roots LocalStore::findRoots(bool censor)
 
 void LocalStore::findPlatformRoots(UncheckedRoots & unchecked)
 {
-    // lsof is really slow on OS X. This actually causes the gc-concurrent.sh test to fail.
-    // See: https://github.com/NixOS/nix/issues/3011
-    // Because of this we disable lsof when running the tests.
-    if (getEnv("_NIX_TEST_NO_LSOF") != "1") {
-        try {
-            std::regex lsofRegex(R"(^n(/.*)$)");
-            auto lsofLines =
-                tokenizeString<std::vector<std::string>>(runProgram(LSOF, true, { "-n", "-w", "-F", "n" }), "\n");
-            for (const auto & line : lsofLines) {
-                std::smatch match;
-                if (std::regex_match(line, match, lsofRegex))
-                    unchecked[match[1]].emplace("{lsof}");
-            }
-        } catch (ExecError & e) {
-            /* lsof not installed, lsof failed */
+    // N.B. This is (read: undertested!) fallback code only used for
+    // non-Darwin, non-Linux platforms. Both major platforms have
+    // platform-specific code in src/libstore/platform/
+    try {
+        std::regex lsofRegex(R"(^n(/.*)$)");
+        auto lsofLines =
+            tokenizeString<std::vector<std::string>>(runProgram(LSOF, true, { "-n", "-w", "-F", "n" }), "\n");
+        for (const auto & line : lsofLines) {
+            std::smatch match;
+            if (std::regex_match(line, match, lsofRegex))
+                unchecked[match[1]].emplace("{lsof}");
         }
+    } catch (ExecError & e) {
+        /* lsof not installed, lsof failed */
     }
 }
 
diff --git a/tests/functional/build.sh b/tests/functional/build.sh
index 95a20dc6a..a540cf8fd 100644
--- a/tests/functional/build.sh
+++ b/tests/functional/build.sh
@@ -142,6 +142,8 @@ test "$(<<<"$out" grep -E '^error:' | wc -l)" = 2
 <<<"$out" grepQuiet -E "hash mismatch in fixed-output derivation '.*-x1\\.drv'"
 <<<"$out" grepQuiet -vE "hash mismatch in fixed-output derivation '.*-x3\\.drv'"
 <<<"$out" grepQuiet -vE "hash mismatch in fixed-output derivation '.*-x2\\.drv'"
+<<<"$out" grepQuiet -E "likely URL: https://meow.puppy.forge/puppy.tar.gz"
+<<<"$out" grepQuiet -vE "likely URL: https://kitty.forge/cat.tar.gz"
 <<<"$out" grepQuiet -E "error: build of '.*-x[1-4]\\.drv\\^out', '.*-x[1-4]\\.drv\\^out', '.*-x[1-4]\\.drv\\^out', '.*-x[1-4]\\.drv\\^out' failed"
 
 out="$(nix build -f fod-failing.nix -L x1 x2 x3 --keep-going 2>&1)" && status=0 || status=$?
@@ -151,6 +153,9 @@ test "$(<<<"$out" grep -E '^error:' | wc -l)" = 4
 <<<"$out" grepQuiet -E "hash mismatch in fixed-output derivation '.*-x1\\.drv'"
 <<<"$out" grepQuiet -E "hash mismatch in fixed-output derivation '.*-x3\\.drv'"
 <<<"$out" grepQuiet -E "hash mismatch in fixed-output derivation '.*-x2\\.drv'"
+<<<"$out" grepQuiet -E "likely URL: https://meow.puppy.forge/puppy.tar.gz"
+<<<"$out" grepQuiet -E "likely URL: https://kitty.forge/cat.tar.gz"
+<<<"$out" grepQuiet -E "likely URL: \(unknown\)"
 <<<"$out" grepQuiet -E "error: build of '.*-x[1-3]\\.drv\\^out', '.*-x[1-3]\\.drv\\^out', '.*-x[1-3]\\.drv\\^out' failed"
 
 out="$(nix build -f fod-failing.nix -L x4 2>&1)" && status=0 || status=$?
diff --git a/tests/functional/fod-failing.nix b/tests/functional/fod-failing.nix
index 37c04fe12..b63fbd900 100644
--- a/tests/functional/fod-failing.nix
+++ b/tests/functional/fod-failing.nix
@@ -6,6 +6,7 @@ rec {
       ''
         echo $name > $out
       '';
+    url = "https://meow.puppy.forge/puppy.tar.gz";
     outputHashMode = "recursive";
     outputHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
   };
@@ -15,6 +16,7 @@ rec {
       ''
         echo $name > $out
       '';
+    urls = "https://kitty.forge/cat.tar.gz";
     outputHashMode = "recursive";
     outputHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
   };