From 38c8807c5ac5cdc7c8d5f6ff48b521b0a2e3c81c Mon Sep 17 00:00:00 2001
From: Evan Wilde <etceterawilde@gmail.com>
Date: Fri, 11 Nov 2022 09:59:59 -0800
Subject: Ninja: Avoid re-linking a Swift executable on every build

Swift doesn't emit swiftmodules for executables, so we shouldn't put it
in dependency graph.  Ninja sees the "missing" dependency and always
tries to rebuild/re-link the target.
---
 Source/cmNinjaNormalTargetGenerator.cxx           |  4 +++-
 Tests/RunCMake/Swift/NoWorkToDo-nowork-stdout.txt |  1 +
 Tests/RunCMake/Swift/NoWorkToDo.cmake             |  2 ++
 Tests/RunCMake/Swift/RunCMakeTest.cmake           | 10 ++++++++++
 Tests/RunCMake/Swift/hello.swift                  |  0
 5 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 Tests/RunCMake/Swift/NoWorkToDo-nowork-stdout.txt
 create mode 100644 Tests/RunCMake/Swift/NoWorkToDo.cmake
 create mode 100644 Tests/RunCMake/Swift/hello.swift

diff --git a/Source/cmNinjaNormalTargetGenerator.cxx b/Source/cmNinjaNormalTargetGenerator.cxx
index 895a4c3..21409d7 100644
--- a/Source/cmNinjaNormalTargetGenerator.cxx
+++ b/Source/cmNinjaNormalTargetGenerator.cxx
@@ -1112,7 +1112,9 @@ void cmNinjaNormalTargetGenerator::WriteLinkStatement(
           this->GetObjectFilePath(source, config));
       }
     }
-    linkBuild.Outputs.push_back(vars["SWIFT_MODULE"]);
+    if (targetType != cmStateEnums::EXECUTABLE) {
+      linkBuild.Outputs.push_back(vars["SWIFT_MODULE"]);
+    }
   } else {
     linkBuild.ExplicitDeps = this->GetObjects(config);
   }
diff --git a/Tests/RunCMake/Swift/NoWorkToDo-nowork-stdout.txt b/Tests/RunCMake/Swift/NoWorkToDo-nowork-stdout.txt
new file mode 100644
index 0000000..60a9228
--- /dev/null
+++ b/Tests/RunCMake/Swift/NoWorkToDo-nowork-stdout.txt
@@ -0,0 +1 @@
+^ninja: no work to do
diff --git a/Tests/RunCMake/Swift/NoWorkToDo.cmake b/Tests/RunCMake/Swift/NoWorkToDo.cmake
new file mode 100644
index 0000000..e86a861
--- /dev/null
+++ b/Tests/RunCMake/Swift/NoWorkToDo.cmake
@@ -0,0 +1,2 @@
+enable_language(Swift)
+add_executable(hello hello.swift)
diff --git a/Tests/RunCMake/Swift/RunCMakeTest.cmake b/Tests/RunCMake/Swift/RunCMakeTest.cmake
index 21d5a25..7f4464d 100644
--- a/Tests/RunCMake/Swift/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Swift/RunCMakeTest.cmake
@@ -14,6 +14,16 @@ elseif(RunCMake_GENERATOR STREQUAL Ninja)
       run_cmake(SwiftMultiArch)
       unset(RunCMake_TEST_OPTIONS)
     endif()
+
+    # Test that a second build with no changes does nothing.
+    block()
+      run_cmake(NoWorkToDo)
+      set(RunCMake_TEST_NO_CLEAN 1)
+      set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/NoWorkToDo-build)
+      set(RunCMake_TEST_OUTPUT_MERGE 1)
+      run_cmake_command(NoWorkToDo-build ${CMAKE_COMMAND} --build .)
+      run_cmake_command(NoWorkToDo-nowork ${CMAKE_COMMAND} --build . -- -d explain)
+    endblock()
   endif()
 elseif(RunCMake_GENERATOR STREQUAL "Ninja Multi-Config")
   if(CMAKE_Swift_COMPILER)
diff --git a/Tests/RunCMake/Swift/hello.swift b/Tests/RunCMake/Swift/hello.swift
new file mode 100644
index 0000000..e69de29
-- 
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