From 609c949061470473d40bd81494458710634b941d Mon Sep 17 00:00:00 2001
From: Martin Duffy <martin.duffy@kitware.com>
Date: Thu, 20 Feb 2025 11:04:26 -0500
Subject: add_dependencies: Allow calling with no dependencies

Fixes: #26713
---
 Help/command/add_dependencies.rst                    | 5 ++++-
 Help/release/dev/add-dependency-one-arg.rst          | 4 ++++
 Source/cmAddDependenciesCommand.cxx                  | 2 +-
 Tests/RunCMake/add_dependencies/NoArgs-result.txt    | 1 +
 Tests/RunCMake/add_dependencies/NoArgs-stderr.txt    | 4 ++++
 Tests/RunCMake/add_dependencies/NoArgs.cmake         | 1 +
 Tests/RunCMake/add_dependencies/NoDependencies.cmake | 3 +++
 Tests/RunCMake/add_dependencies/RunCMakeTest.cmake   | 2 ++
 8 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 Help/release/dev/add-dependency-one-arg.rst
 create mode 100644 Tests/RunCMake/add_dependencies/NoArgs-result.txt
 create mode 100644 Tests/RunCMake/add_dependencies/NoArgs-stderr.txt
 create mode 100644 Tests/RunCMake/add_dependencies/NoArgs.cmake
 create mode 100644 Tests/RunCMake/add_dependencies/NoDependencies.cmake

diff --git a/Help/command/add_dependencies.rst b/Help/command/add_dependencies.rst
index c619212..b0dd494 100644
--- a/Help/command/add_dependencies.rst
+++ b/Help/command/add_dependencies.rst
@@ -12,7 +12,6 @@ ensure that they build before ``<target>`` does.  A top-level target
 is one created by one of the :command:`add_executable`,
 :command:`add_library`, or :command:`add_custom_target` commands
 (but not targets generated by CMake like ``install``).
-At least one ``<target-dependency>`` must be given.
 
 Dependencies added to an :ref:`imported target <Imported Targets>`
 or an :ref:`interface library <Interface Libraries>` are followed
@@ -32,6 +31,10 @@ transitively in its place since the target itself does not build.
   finished before sources in ``<target>`` start compiling; this
   ensures generated sources are available.
 
+.. versionchanged:: 4.1
+  The command may be called with no dependencies.
+  Previously, at least one dependency was required.
+
 See Also
 ^^^^^^^^
 
diff --git a/Help/release/dev/add-dependency-one-arg.rst b/Help/release/dev/add-dependency-one-arg.rst
new file mode 100644
index 0000000..e077258
--- /dev/null
+++ b/Help/release/dev/add-dependency-one-arg.rst
@@ -0,0 +1,4 @@
+add-dependency-one-arg
+----------------------
+
+* The :command:`add_dependencies` command may be called with no dependencies.
diff --git a/Source/cmAddDependenciesCommand.cxx b/Source/cmAddDependenciesCommand.cxx
index aa04018..1dcf8a8 100644
--- a/Source/cmAddDependenciesCommand.cxx
+++ b/Source/cmAddDependenciesCommand.cxx
@@ -12,7 +12,7 @@
 bool cmAddDependenciesCommand(std::vector<std::string> const& args,
                               cmExecutionStatus& status)
 {
-  if (args.size() < 2) {
+  if (args.empty()) {
     status.SetError("called with incorrect number of arguments");
     return false;
   }
diff --git a/Tests/RunCMake/add_dependencies/NoArgs-result.txt b/Tests/RunCMake/add_dependencies/NoArgs-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/add_dependencies/NoArgs-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/add_dependencies/NoArgs-stderr.txt b/Tests/RunCMake/add_dependencies/NoArgs-stderr.txt
new file mode 100644
index 0000000..8af39ab
--- /dev/null
+++ b/Tests/RunCMake/add_dependencies/NoArgs-stderr.txt
@@ -0,0 +1,4 @@
+CMake Error at NoArgs.cmake:[0-9]+ \(add_dependencies\):
+  add_dependencies called with incorrect number of arguments
+Call Stack \(most recent call first\):
+  CMakeLists\.txt:[0-9]+ \(include\)
diff --git a/Tests/RunCMake/add_dependencies/NoArgs.cmake b/Tests/RunCMake/add_dependencies/NoArgs.cmake
new file mode 100644
index 0000000..6c6da2b
--- /dev/null
+++ b/Tests/RunCMake/add_dependencies/NoArgs.cmake
@@ -0,0 +1 @@
+add_dependencies()
diff --git a/Tests/RunCMake/add_dependencies/NoDependencies.cmake b/Tests/RunCMake/add_dependencies/NoDependencies.cmake
new file mode 100644
index 0000000..21e0b89
--- /dev/null
+++ b/Tests/RunCMake/add_dependencies/NoDependencies.cmake
@@ -0,0 +1,3 @@
+enable_language(C)
+add_library(a a.c)
+add_dependencies(a ${noDependencies})
diff --git a/Tests/RunCMake/add_dependencies/RunCMakeTest.cmake b/Tests/RunCMake/add_dependencies/RunCMakeTest.cmake
index 507d43f..502aa7c 100644
--- a/Tests/RunCMake/add_dependencies/RunCMakeTest.cmake
+++ b/Tests/RunCMake/add_dependencies/RunCMakeTest.cmake
@@ -1,5 +1,7 @@
 include(RunCMake)
 
+run_cmake(NoArgs)
 run_cmake(NoTarget)
+run_cmake(NoDependencies)
 run_cmake(ReadOnlyProperty)
 run_cmake(RetrieveDependencies)
-- 
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