From f97da4b11c8d38f3bb002407076bf56acba8675b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Sat, 25 May 2024 23:06:56 +0200
Subject: [PATCH 1/2] libutil/source-accessor: custom error if source does not
 exist

This allows better error handling by catching this error in particular.
---
 src/libutil/source-accessor.cc | 2 +-
 src/libutil/source-accessor.hh | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libutil/source-accessor.cc b/src/libutil/source-accessor.cc
index 66093d2cc..e797951c7 100644
--- a/src/libutil/source-accessor.cc
+++ b/src/libutil/source-accessor.cc
@@ -53,7 +53,7 @@ SourceAccessor::Stat SourceAccessor::lstat(const CanonPath & path)
     if (auto st = maybeLstat(path))
         return *st;
     else
-        throw Error("path '%s' does not exist", showPath(path));
+        throw FileNotFound("path '%s' does not exist", showPath(path));
 }
 
 void SourceAccessor::setPathDisplay(std::string displayPrefix, std::string displaySuffix)
diff --git a/src/libutil/source-accessor.hh b/src/libutil/source-accessor.hh
index d7fb0af5f..cc8db01f5 100644
--- a/src/libutil/source-accessor.hh
+++ b/src/libutil/source-accessor.hh
@@ -29,6 +29,8 @@ enum class SymlinkResolution {
     Full,
 };
 
+MakeError(FileNotFound, Error);
+
 /**
  * A read-only filesystem abstraction. This is used by the Nix
  * evaluator and elsewhere for accessing sources in various

From ffe6ba69d6a3a290e56a2891d05c91059f4b9e3a Mon Sep 17 00:00:00 2001
From: Pierre Bourdon <delroth@gmail.com>
Date: Thu, 23 May 2024 02:52:54 +0200
Subject: [PATCH 2/2] repl: do not crash when tab-completing import errors

File not found while importing is not currently caught by the tab-completion handler.

Original bug report: https://git.lix.systems/lix-project/lix/issues/340
Fix has been adapted from https://gerrit.lix.systems/c/lix/+/1189

Example crash:

$ cat /tmp/foo.nix
{
  someImport = import ./this_file_does_not_exist;
}
$ ./src/nix/nix repl --file /tmp/foo.nix
warning: unknown experimental feature 'repl-flake'
Nix 2.23.0pre20240517_dirty
Type :? for help.
Loading installable ''...
Added 1 variables.
nix-repl> someImport.<TAB>
---
 src/libcmd/repl.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libcmd/repl.cc b/src/libcmd/repl.cc
index a069dd52c..e5d3f6f15 100644
--- a/src/libcmd/repl.cc
+++ b/src/libcmd/repl.cc
@@ -304,6 +304,8 @@ StringSet NixRepl::completePrefix(const std::string & prefix)
             // Quietly ignore evaluation errors.
         } catch (BadURL & e) {
             // Quietly ignore BadURL flake-related errors.
+        } catch (FileNotFound & e) {
+            // Quietly ignore non-existent file beeing `import`-ed.
         }
     }