From 180c2f8de8b1cc19e7dafeaf571d8fa2b203d78f Mon Sep 17 00:00:00 2001
From: Jean-Christophe Fillion-Robin <jchris.fillionr@kitware.com>
Date: Wed, 8 Aug 2018 23:40:00 -0400
Subject: Ninja: Fix dupbuild error skipping alias with conflicting custom
 command

See-also: https://issues.slicer.org/view.php?id=4595

Reported-by: Isaiah Norton <inorton@bwh.harvard.edu>
---
 Source/cmGlobalNinjaGenerator.cxx                  |  6 ++++
 .../Ninja/PreventTargetAliasesDupBuildRule.cmake   | 41 ++++++++++++++++++++++
 Tests/RunCMake/Ninja/RunCMakeTest.cmake            |  7 ++++
 3 files changed, 54 insertions(+)
 create mode 100644 Tests/RunCMake/Ninja/PreventTargetAliasesDupBuildRule.cmake

diff --git a/Source/cmGlobalNinjaGenerator.cxx b/Source/cmGlobalNinjaGenerator.cxx
index 6f7e82a..531f79e 100644
--- a/Source/cmGlobalNinjaGenerator.cxx
+++ b/Source/cmGlobalNinjaGenerator.cxx
@@ -1112,6 +1112,12 @@ void cmGlobalNinjaGenerator::WriteTargetAliases(std::ostream& os)
       continue;
     }
 
+    // Don't write alias if there is a already a custom command with
+    // matching output
+    if (this->HasCustomCommandOutput(ta.first)) {
+      continue;
+    }
+
     cmNinjaDeps deps;
     this->AppendTargetOutputs(ta.second, deps);
 
diff --git a/Tests/RunCMake/Ninja/PreventTargetAliasesDupBuildRule.cmake b/Tests/RunCMake/Ninja/PreventTargetAliasesDupBuildRule.cmake
new file mode 100644
index 0000000..da6f86a
--- /dev/null
+++ b/Tests/RunCMake/Ninja/PreventTargetAliasesDupBuildRule.cmake
@@ -0,0 +1,41 @@
+cmake_minimum_required(VERSION 3.12)
+project(Test LANGUAGES C)
+
+# fake launcher executable
+set(input_launcher_executable ${CMAKE_CURRENT_BINARY_DIR}/fake_launcher_executable)
+file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/fake_launcher_executable "")
+
+# application and executable name
+set(application_target "HelloApp")
+set(application_name "Hello")
+set(executable_name "Hello")
+
+# target built in "<root>/bin"
+add_executable(${application_target} hello.c)
+set_target_properties(${application_target} PROPERTIES
+  OUTPUT_NAME ${executable_name}
+  RUNTIME_OUTPUT_DIRECTORY  ${CMAKE_CURRENT_BINARY_DIR}/bin
+  )
+
+# configured launcher in "<root>"
+set(configured_launcher_executable "${CMAKE_CURRENT_BINARY_DIR}/${application_name}")
+
+# create command to copy the launcher
+add_custom_command(
+  DEPENDS
+    ${input_launcher_executable}
+  OUTPUT
+    ${configured_launcher_executable}
+  COMMAND
+    ${CMAKE_COMMAND} -E copy ${input_launcher_executable} ${configured_launcher_executable}
+  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+  COMMENT
+    "Configuring application launcher: ${application_name}"
+  )
+
+add_custom_target(Configure${application_name}Launcher ALL
+  DEPENDS
+    ${application_target}
+    ${input_launcher_executable}
+    ${configured_launcher_executable}
+  )
diff --git a/Tests/RunCMake/Ninja/RunCMakeTest.cmake b/Tests/RunCMake/Ninja/RunCMakeTest.cmake
index b6e6cd4..e0ddc9c 100644
--- a/Tests/RunCMake/Ninja/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Ninja/RunCMakeTest.cmake
@@ -278,3 +278,10 @@ foreach(ninja_output_path_prefix "sub space" "sub")
   run_sub_cmake(SubDirPrefix "${ninja_output_path_prefix}")
   run_sub_cmake(CustomCommandWorkingDirectory "${ninja_output_path_prefix}")
 endforeach(ninja_output_path_prefix)
+
+function (run_PreventTargetAliasesDupBuildRule)
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/PreventTargetAliasesDupBuildRule-build)
+  run_cmake(PreventTargetAliasesDupBuildRule)
+  run_ninja("${RunCMake_TEST_BINARY_DIR}" -w dupbuild=err)
+endfunction ()
+run_PreventTargetAliasesDupBuildRule()
-- 
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