Makefile: Add policy CMP0113 to avoid duplication of custom commands

Do not attach a custom command to a target if it is already attached to one of
the target's dependencies.  The command's output will be available by the time
the target needs it because the dependency containing the command will have
already been built.

This may break existing projects that do not properly mark non-created
outputs with the `SYMBOLIC` property.  Previously a chain of two custom
commands whose intermediate dependency is not created would put both
commands in a dependent project's Makefile even if the first command is
also in its dependency's Makefile.  The first command would run twice
but the build would work.  Now the second command needs an explicit
`SYMBOLIC` mark on its input to tell CMake that it is not expected to
exist.  To maintain compatibility with projects that left out the mark,
add a policy activating the behavior.

12 files changed, 56 insertions, 0 deletions

diff --git a/Tests/RunCMake/Make/CMP0113-Common.cmake b/Tests/RunCMake/Make/CMP0113-Common.cmake
new file mode 100644
index 0000000..8ce26c4
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-Common.cmake
@@ -0,0 +1,17 @@
+add_custom_command(
+  OUTPUT output-not-created
+  COMMAND ${CMAKE_COMMAND} -E echo output-not-created
+  DEPENDS ${CMAKE_CURRENT_LIST_FILE}
+  VERBATIM
+  )
+
+add_custom_command(
+  OUTPUT output-created
+  COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_LIST_FILE} output-created
+  DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/output-not-created
+  VERBATIM
+  )
+
+add_custom_target(drive1 ALL DEPENDS output-not-created)
+add_custom_target(drive2 ALL DEPENDS output-created)
+add_dependencies(drive2 drive1)
diff --git a/Tests/RunCMake/Make/CMP0113-NEW-build-gnu-stderr.txt b/Tests/RunCMake/Make/CMP0113-NEW-build-gnu-stderr.txt
new file mode 100644
index 0000000..0af354a
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-NEW-build-gnu-stderr.txt
@@ -0,0 +1,5 @@
+No rule to make target [^
+]*output-not-created[^
+]*, needed by [^
+]*output-created[^
+]*
diff --git a/Tests/RunCMake/Make/CMP0113-NEW-build-result.txt b/Tests/RunCMake/Make/CMP0113-NEW-build-result.txt
new file mode 100644
index 0000000..d197c91
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-NEW-build-result.txt
@@ -0,0 +1 @@
+[^0]
diff --git a/Tests/RunCMake/Make/CMP0113-NEW-build-stderr.txt b/Tests/RunCMake/Make/CMP0113-NEW-build-stderr.txt
new file mode 100644
index 0000000..8d98f9d
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-NEW-build-stderr.txt
@@ -0,0 +1 @@
+.*
diff --git a/Tests/RunCMake/Make/CMP0113-NEW-build-stdout.txt b/Tests/RunCMake/Make/CMP0113-NEW-build-stdout.txt
new file mode 100644
index 0000000..a6b851e
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-NEW-build-stdout.txt
@@ -0,0 +1 @@
+Generating output-not-created.*Built target drive1
diff --git a/Tests/RunCMake/Make/CMP0113-NEW.cmake b/Tests/RunCMake/Make/CMP0113-NEW.cmake
new file mode 100644
index 0000000..a2d1db5
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-NEW.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0113 NEW)
+include(CMP0113-Common.cmake)
diff --git a/Tests/RunCMake/Make/CMP0113-OLD-build-stdout.txt b/Tests/RunCMake/Make/CMP0113-OLD-build-stdout.txt
new file mode 100644
index 0000000..f6e1f0f
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-OLD-build-stdout.txt
@@ -0,0 +1 @@
+Generating output-not-created.*Built target drive1.*Generating output-not-created.*Built target drive2
diff --git a/Tests/RunCMake/Make/CMP0113-OLD.cmake b/Tests/RunCMake/Make/CMP0113-OLD.cmake
new file mode 100644
index 0000000..b6ab120
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-OLD.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0113 OLD)
+include(CMP0113-Common.cmake)
diff --git a/Tests/RunCMake/Make/CMP0113-WARN-build-stdout.txt b/Tests/RunCMake/Make/CMP0113-WARN-build-stdout.txt
new file mode 100644
index 0000000..f6e1f0f
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-WARN-build-stdout.txt
@@ -0,0 +1 @@
+Generating output-not-created.*Built target drive1.*Generating output-not-created.*Built target drive2
diff --git a/Tests/RunCMake/Make/CMP0113-WARN.cmake b/Tests/RunCMake/Make/CMP0113-WARN.cmake
new file mode 100644
index 0000000..48e035a
--- /dev/null
+++ b/Tests/RunCMake/Make/CMP0113-WARN.cmake
@@ -0,0 +1,2 @@
+# Policy CMP0113 not set.
+include(CMP0113-Common.cmake)
diff --git a/Tests/RunCMake/Make/RunCMakeTest.cmake b/Tests/RunCMake/Make/RunCMakeTest.cmake
index 32aafca..5562aca 100644
--- a/Tests/RunCMake/Make/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Make/RunCMakeTest.cmake
@@ -41,3 +41,25 @@ run_VerboseBuild()
 
 run_cmake(CustomCommandDepfile-ERROR)
 run_cmake(IncludeRegexSubdir)
+
+function(run_CMP0113 val)
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/CMP0113-${val}-build)
+  run_cmake(CMP0113-${val})
+  set(RunCMake_TEST_NO_CLEAN 1)
+  set(_backup_lang "$ENV{LANG}")
+  set(_backup_lc_Messages "$ENV{LC_MESSAGES}")
+  if(MAKE_IS_GNU)
+    set(RunCMake-stderr-file CMP0113-${val}-build-gnu-stderr.txt)
+    set(ENV{LANG} "C")
+    set(ENV{LC_MESSAGES} "C")
+  endif()
+  run_cmake_command(CMP0113-${val}-build ${CMAKE_COMMAND} --build .)
+  set(ENV{LANG} "${_backup_lang}")
+  set(ENV{LC_MESSAGES} "${_backup_lc_messages}")
+endfunction()
+
+if(NOT RunCMake_GENERATOR STREQUAL "Watcom WMake")
+  run_CMP0113(WARN)
+  run_CMP0113(OLD)
+  run_CMP0113(NEW)
+endif()
diff --git a/Tests/RunCMake/TargetPolicies/PolicyList-stderr.txt b/Tests/RunCMake/TargetPolicies/PolicyList-stderr.txt
index fe13e81..b3f3a5e 100644
--- a/Tests/RunCMake/TargetPolicies/PolicyList-stderr.txt
+++ b/Tests/RunCMake/TargetPolicies/PolicyList-stderr.txt
@@ -33,6 +33,7 @@
    \* CMP0105
    \* CMP0108
    \* CMP0112
+   \* CMP0113
 
 Call Stack \(most recent call first\):
   CMakeLists.txt:3 \(include\)