ExternalProject: Avoid reconfigure when updates are disconnected

When UPDATE_DISCONNECTED is true, create separate update_disconnected
and patch_disconnected targets which have ALWAYS set to false.
Make the configure step depend on patch_disconnected in this case too.
This ensures the configure, build, install and test steps are not
executed unnecessarily when updates are disconnected.

Make the update and patch commands depend on the details of those
steps. This ensures they are re-executed when any of those details
change, even if updates are disconnected.

Allow updates to occur even if UPDATE_DISCONNECTED is true, but don't
contact the remote in that case. If asked to update to a ref that isn't known
locally, that is now detected and causes a fatal error when updates are
disconnected. Previously, the build would have silently and erroneously
continued to use the old ref.

Fixes: #16419, #19703, #21146

1 files changed, 26 insertions, 16 deletions

diff --git a/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake b/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
index 394df87..08e533b 100644
--- a/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
+++ b/Tests/ExternalProjectUpdate/ExternalProjectUpdateTest.cmake
@@ -1,8 +1,14 @@
 # Set the ExternalProject GIT_TAG to desired_tag, and make sure the
 # resulting checked out version is resulting_sha and rebuild.
 # This check's the correct behavior of the ExternalProject UPDATE_COMMAND.
-# Also verify that a fetch only occurs when fetch_expected is 1.
-macro(check_a_tag desired_tag resulting_sha fetch_expected update_strategy)
+# Also verify that a fetch only occurs when fetch_expected_tsX is 1.
+macro(check_a_tag
+  desired_tag
+  resulting_sha
+  fetch_expected_ts1  # TutorialStep1-GIT
+  fetch_expected_ts2  # TutorialStep2-GIT
+  update_strategy
+)
   message( STATUS "Checking ExternalProjectUpdate to tag: ${desired_tag}" )
 
   # Remove the FETCH_HEAD file, so we can check if it gets replaced with a 'git
@@ -12,7 +18,11 @@ macro(check_a_tag desired_tag resulting_sha fetch_expected update_strategy)
 
   # Give ourselves a marker in the output. It is difficult to tell where we
   # are up to without this
-  message(STATUS "===> check_a_tag ${desired_tag} ${resulting_sha} ${fetch_expected} ${update_strategy}")
+  message(STATUS "===> check_a_tag: "
+    "${desired_tag} ${resulting_sha} "
+    "${fetch_expected_ts1} ${fetch_expected_ts2} "
+    "${update_strategy}"
+  )
 
   # Configure
   execute_process(COMMAND ${CMAKE_COMMAND}
@@ -58,10 +68,10 @@ was expected."
     )
   endif()
 
-  if( NOT EXISTS ${FETCH_HEAD_file} AND ${fetch_expected})
+  if( NOT EXISTS ${FETCH_HEAD_file} AND ${fetch_expected_ts1})
     message( FATAL_ERROR "Fetch did NOT occur when it was expected.")
   endif()
-  if( EXISTS ${FETCH_HEAD_file} AND NOT ${fetch_expected})
+  if( EXISTS ${FETCH_HEAD_file} AND NOT ${fetch_expected_ts1})
     message( FATAL_ERROR "Fetch DID occur when it was not expected.")
   endif()
 
@@ -154,10 +164,10 @@ was expected."
     )
   endif()
 
-  if( NOT EXISTS ${FETCH_HEAD_file} AND ${fetch_expected})
+  if( NOT EXISTS ${FETCH_HEAD_file} AND ${fetch_expected_ts2})
     message( FATAL_ERROR "Fetch did NOT occur when it was expected.")
   endif()
-  if( EXISTS ${FETCH_HEAD_file} AND NOT ${fetch_expected})
+  if( EXISTS ${FETCH_HEAD_file} AND NOT ${fetch_expected_ts2})
     message( FATAL_ERROR "Fetch DID occur when it was not expected.")
   endif()
 endmacro()
@@ -179,16 +189,16 @@ endif()
 file(REMOVE_RECURSE ${ExternalProjectUpdate_BINARY_DIR}/CMakeExternals)
 
 if(do_git_tests)
-  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 REBASE)
-  check_a_tag(tag1          d1970730310fe8bc07e73f15dc570071f9f9654a 1 REBASE)
+  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 1 REBASE)
+  check_a_tag(tag1          d1970730310fe8bc07e73f15dc570071f9f9654a 1 0 REBASE)
   # With the Git UPDATE_COMMAND performance patch, this will not require a
   # 'git fetch'
-  check_a_tag(tag1          d1970730310fe8bc07e73f15dc570071f9f9654a 0 REBASE)
-  check_a_tag(tag2          5842b503ba4113976d9bb28d57b5aee1ad2736b7 1 REBASE)
-  check_a_tag(d19707303     d1970730310fe8bc07e73f15dc570071f9f9654a 0 REBASE)
-  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 REBASE)
+  check_a_tag(tag1          d1970730310fe8bc07e73f15dc570071f9f9654a 0 0 REBASE)
+  check_a_tag(tag2          5842b503ba4113976d9bb28d57b5aee1ad2736b7 1 0 REBASE)
+  check_a_tag(d19707303     d1970730310fe8bc07e73f15dc570071f9f9654a 0 0 REBASE)
+  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 1 REBASE)
   # This is a remote symbolic ref, so it will always trigger a 'git fetch'
-  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 REBASE)
+  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 1 REBASE)
 
   foreach(strategy IN ITEMS CHECKOUT REBASE_CHECKOUT)
     # Move local master back, then apply a change that will cause a conflict
@@ -222,7 +232,7 @@ if(do_git_tests)
       message(FATAL_ERROR "Could not commit conflicting change.")
     endif()
     # This should discard our commit but leave behind an annotated tag
-    check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 ${strategy})
+    check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 1 ${strategy})
   endforeach()
 
   # This file matches a .gitignore rule that the last commit defines. We can't
@@ -232,7 +242,7 @@ if(do_git_tests)
   # doesn't choke on it.
   set(ignoredFile ${ExternalProjectUpdate_BINARY_DIR}/CMakeExternals/Source/TutorialStep1-GIT/ignored_item)
   file(TOUCH ${ignoredFile})
-  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 REBASE)
+  check_a_tag(origin/master b5752a26ae448410926b35c275af3c192a53722e 1 1 REBASE)
   if(NOT EXISTS ${ignoredFile})
     message(FATAL_ERROR "Ignored file is missing")
   endif()