From 38e2299fc84aa31ca73bebf1efc9123dbc7bee1a Mon Sep 17 00:00:00 2001
From: Asit Dhal <dhal.asitk@gmail.com>
Date: Thu, 7 Jan 2021 07:30:00 +0100
Subject: list(REMOVE_ITEM): Make removal of an empty item a no-op.

Fixes: #21663
---
 Source/cmListCommand.cxx                        | 7 ++++---
 Tests/CMakeTests/ListTest.cmake.in              | 3 +--
 Tests/RunCMake/list/REMOVE_ITEM-NoItemArg.cmake | 5 +++++
 Tests/RunCMake/list/RunCMakeTest.cmake          | 1 +
 4 files changed, 11 insertions(+), 5 deletions(-)
 create mode 100644 Tests/RunCMake/list/REMOVE_ITEM-NoItemArg.cmake

diff --git a/Source/cmListCommand.cxx b/Source/cmListCommand.cxx
index 53c871b..fdddb45 100644
--- a/Source/cmListCommand.cxx
+++ b/Source/cmListCommand.cxx
@@ -422,9 +422,10 @@ bool HandleJoinCommand(std::vector<std::string> const& args,
 bool HandleRemoveItemCommand(std::vector<std::string> const& args,
                              cmExecutionStatus& status)
 {
-  if (args.size() < 3) {
-    status.SetError("sub-command REMOVE_ITEM requires two or more arguments.");
-    return false;
+  assert(args.size() >= 2);
+
+  if (args.size() == 2) {
+    return true;
   }
 
   const std::string& listName = args[1];
diff --git a/Tests/CMakeTests/ListTest.cmake.in b/Tests/CMakeTests/ListTest.cmake.in
index 785f41d..76737e5 100644
--- a/Tests/CMakeTests/ListTest.cmake.in
+++ b/Tests/CMakeTests/ListTest.cmake.in
@@ -142,9 +142,8 @@ set(Find-List-Only-STDERR "three")
 set(Insert-List-Only-STDERR "at least three")
 set(Length-List-Only-STDERR "two")
 set(Remove_At-List-Only-STDERR "at least two")
-set(Remove_Item-List-Only-STDERR "two or more")
 
-foreach(cmd IN ITEMS Find Get Insert Length Remove_At Remove_Item)
+foreach(cmd IN ITEMS Find Get Insert Length Remove_At)
   string(TOUPPER ${cmd} cmd_upper)
   set(${cmd}-List-Only-RESULT 1)
   set(${cmd}-List-Only-STDERR ".*CMake Error at List-${cmd}-List-Only.cmake:1 \\(list\\):.*list sub-command ${cmd_upper} requires ${${cmd}-List-Only-STDERR} arguments.*")
diff --git a/Tests/RunCMake/list/REMOVE_ITEM-NoItemArg.cmake b/Tests/RunCMake/list/REMOVE_ITEM-NoItemArg.cmake
new file mode 100644
index 0000000..f69c024
--- /dev/null
+++ b/Tests/RunCMake/list/REMOVE_ITEM-NoItemArg.cmake
@@ -0,0 +1,5 @@
+set(ls "a" "b" "c")
+list(REMOVE_ITEM ls alpha)
+if (NOT ls STREQUAL "a;b;c")
+  message(FATAL_ERROR "list(REMOVE_ITEM) modified for empty item")
+endif ()
diff --git a/Tests/RunCMake/list/RunCMakeTest.cmake b/Tests/RunCMake/list/RunCMakeTest.cmake
index b4a91bc..c11891c 100644
--- a/Tests/RunCMake/list/RunCMakeTest.cmake
+++ b/Tests/RunCMake/list/RunCMakeTest.cmake
@@ -30,6 +30,7 @@ run_cmake(FILTER-NotList)
 run_cmake(REMOVE_AT-NotList)
 run_cmake(REMOVE_DUPLICATES-NotList)
 run_cmake(REMOVE_ITEM-NotList)
+run_cmake(REMOVE_ITEM-NoItemArg)
 run_cmake(REVERSE-NotList)
 run_cmake(SORT-NotList)
 
-- 
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