From 06e13465c55a046d22791942680166f048d11f94 Mon Sep 17 00:00:00 2001
From: Cole Helbling <cole.e.helbling@outlook.com>
Date: Tue, 14 May 2024 12:13:14 -0700
Subject: [PATCH 1/2] tests/functional: test both clis warn on unknown settings

---
 tests/functional/eval.sh | 4 ++++
 tests/functional/misc.sh | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/tests/functional/eval.sh b/tests/functional/eval.sh
index c6a475cd0..502170d14 100644
--- a/tests/functional/eval.sh
+++ b/tests/functional/eval.sh
@@ -52,3 +52,7 @@ fi
 
 # Test --arg-from-stdin.
 [[ "$(echo bla | nix eval --raw --arg-from-stdin foo --expr '{ foo }: { inherit foo; }' foo)" = bla ]]
+
+# Test that unknown settings are warned about
+out="$(expectStderr 0 nix eval --option foobar baz --expr '""' --raw)"
+[[ "$(echo "$out" | grep foobar | wc -l)" = 1 ]]
diff --git a/tests/functional/misc.sh b/tests/functional/misc.sh
index af96d20bd..d4379b7ce 100644
--- a/tests/functional/misc.sh
+++ b/tests/functional/misc.sh
@@ -30,3 +30,12 @@ expectStderr 1 nix-instantiate --eval -E '[]' -A 'x' | grepQuiet "should be a se
 expectStderr 1 nix-instantiate --eval -E '{}' -A '1' | grepQuiet "should be a list"
 expectStderr 1 nix-instantiate --eval -E '{}' -A '.' | grepQuiet "empty attribute name"
 expectStderr 1 nix-instantiate --eval -E '[]' -A '1' | grepQuiet "out of range"
+
+# Unknown setting warning
+# NOTE(cole-h): behavior is different depending on the order, which is why we test an unknown option
+# before and after the `'{}'`!
+out="$(expectStderr 0 nix-instantiate --option foobar baz --expr '{}')"
+[[ "$(echo "$out" | grep foobar | wc -l)" = 1 ]]
+
+out="$(expectStderr 0 nix-instantiate '{}' --option foobar baz --expr )"
+[[ "$(echo "$out" | grep foobar | wc -l)" = 1 ]]

From 39a269657e766aaa6d6c678f95362a566173e547 Mon Sep 17 00:00:00 2001
From: Cole Helbling <cole.e.helbling@outlook.com>
Date: Tue, 14 May 2024 12:13:40 -0700
Subject: [PATCH 2/2] libutil/args: warn on unknown settings after parsing all
 flags

---
 doc/manual/rl-next/fix-silent-unknown-options | 28 +++++++++++++++++++
 src/libutil/args.cc                           |  9 +-----
 2 files changed, 29 insertions(+), 8 deletions(-)
 create mode 100644 doc/manual/rl-next/fix-silent-unknown-options

diff --git a/doc/manual/rl-next/fix-silent-unknown-options b/doc/manual/rl-next/fix-silent-unknown-options
new file mode 100644
index 000000000..0977260ac
--- /dev/null
+++ b/doc/manual/rl-next/fix-silent-unknown-options
@@ -0,0 +1,28 @@
+---
+synopsis: Warn on unknown settings anywhere in the command line
+prs: 10701
+---
+
+All `nix` commands will now properly warn when an unknown option is specified anywhere in the command line.
+
+Before:
+
+```console
+$ nix-instantiate --option foobar baz --expr '{}'
+warning: unknown setting 'foobar'
+$ nix-instantiate '{}' --option foobar baz --expr
+$ nix eval --expr '{}' --option foobar baz
+{ }
+```
+
+After:
+
+```console
+$ nix-instantiate --option foobar baz --expr '{}'
+warning: unknown setting 'foobar'
+$ nix-instantiate '{}' --option foobar baz --expr
+warning: unknown setting 'foobar'
+$ nix eval --expr '{}' --option foobar baz
+warning: unknown setting 'foobar'
+{ }
+```
diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index 243e3a5a6..c202facdf 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -268,8 +268,6 @@ void RootArgs::parseCmdline(const Strings & _cmdline, bool allowShebang)
         verbosity = lvlError;
     }
 
-    bool argsSeen = false;
-
     // Heuristic to see if we're invoked as a shebang script, namely,
     // if we have at least one argument, it's the name of an
     // executable file, and it starts with "#!".
@@ -336,10 +334,6 @@ void RootArgs::parseCmdline(const Strings & _cmdline, bool allowShebang)
                 throw UsageError("unrecognised flag '%1%'", arg);
         }
         else {
-            if (!argsSeen) {
-                argsSeen = true;
-                initialFlagsProcessed();
-            }
             pos = rewriteArgs(cmdline, pos);
             pendingArgs.push_back(*pos++);
             if (processArgs(pendingArgs, false))
@@ -349,8 +343,7 @@ void RootArgs::parseCmdline(const Strings & _cmdline, bool allowShebang)
 
     processArgs(pendingArgs, true);
 
-    if (!argsSeen)
-        initialFlagsProcessed();
+    initialFlagsProcessed();
 
     /* Now that we are done parsing, make sure that any experimental
      * feature required by the flags is enabled */