Clean up recent fix for #1892

Restore 906d235 and simplify how __fish_restore_status works

1 files changed, 24 insertions, 17 deletions

diff --git a/share/functions/eval.fish b/share/functions/eval.fish
index 5f06320f..052d4171 100644
--- a/share/functions/eval.fish
+++ b/share/functions/eval.fish
@@ -3,8 +3,8 @@ function eval -S -d "Evaluate parameters as a command"
 	# to preserve the status in case the block that is evaluated
 	# does not modify the status itself.
 	set -l status_copy $status
-	function -S __fish_restore_status
-		return $status_copy
+	function __fish_restore_status
+		return $argv[1]
 	end
 
 	if not set -q argv[2]
@@ -35,22 +35,29 @@ function eval -S -d "Evaluate parameters as a command"
 	if status --is-interactive
 		status --job-control full
 	end
+	__fish_restore_status $status_copy
 
-  # rfish: To eval 'foo', we construct a block "begin ; foo; end <&3 3<&-"
-  # The 'eval2_inner' is a param to 'begin' itself; I believe it does nothing.
-  # Note the redirections are also within the quotes.
-  #
-  # We then pipe this to 'source 3<&0' which dup2's 3 to stdin.
-  #
-  # You might expect that the dup2(3, stdin) should overwrite stdin,
-  # and therefore prevent 'source' from reading the piped-in block. This doesn't happen
-  # because when you pipe to a builtin, we don't overwrite stdin with the read end
-  # of the block; instead we set a separate fd in a variable 'builtin_stdin', which is
-  # what it reads from. So builtins are magic in that, in pipes, their stdin
-  # is not fd 0.
-
-	__fish_restore_status
-	echo "begin; $argv "\n" ;end eval2_inner <&3 3<&-" | source 3<&0
+	# To eval 'foo', we construct a block "begin ; foo; end <&3 3<&-"
+	# Note the redirections are also within the quotes.
+	#
+	# We then pipe this to 'source 3<&0’.
+	#
+	# You might expect that the dup2(3, stdin) should overwrite stdin,
+	# and therefore prevent 'source' from reading the piped-in block. This doesn't happen
+	# because when you pipe to a builtin, we don't overwrite stdin with the read end
+	# of the block; instead we set a separate fd in a variable 'builtin_stdin', which is
+	# what it reads from. So builtins are magic in that, in pipes, their stdin
+	# is not fd 0.
+	#
+	# ‘source’ does not apply the redirections to itself. Instead it saves them and passes
+	# them as block-level redirections to parser.eval(). Ultimately the eval’d code sees
+	# the following redirections (in the following order):
+	#    dup2 0 -> 3
+	#    dup2 pipe -> 0
+	#    dup2 3 -> 0
+	# where the pipe is the pipe we get from piping ‘echo’ to ‘source’. Thus the redirection
+	# effectively makes stdin fd0, instead of the thing that was piped to ‘source’
+	echo "begin; $argv "\n" ;end <&3 3<&-" | source 3<&0
 	set -l res $status
 
 	status --job-control $mode