[cmake-developers] [CMake 0016082]: Support alternative download URL in ExternalProject_Add

[Brad King]

On 04/29/2016 03:40 PM, A. Klitzing wrote:
> I APPEND the log of every failed download and print that only if no
> URL works now. So we reserve the detailed error log of a single
> download attempt.

Thanks.  I added the test case with the patch below and
it causes the ExternalProjectLocal test to fail.  The
download tries both alternatives "a;b" as a single URL.

Also it looks like _ep_add_download_command has a lot
of logic that inspects the URL value.  Your change will
need to account for multiple values there as well.  I think
it may be a bit more involved than the patch so far.

Thanks,
-Brad

diff --git a/Tests/ExternalProjectLocal/CMakeLists.txt b/Tests/ExternalProjectLocal/CMakeLists.txt
index 17f1630..9d4d98b 100644
--- a/Tests/ExternalProjectLocal/CMakeLists.txt
+++ b/Tests/ExternalProjectLocal/CMakeLists.txt
@@ -126,7 +126,8 @@ ExternalProject_Add_Step(${proj} mypatch
 #
 set(proj TutorialStep1-LocalTGZ)
 ExternalProject_Add(${proj}
-  URL "${CMAKE_CURRENT_SOURCE_DIR}/Step1.tgz"
+  URL "${CMAKE_CURRENT_SOURCE_DIR}/missing/Step1.tgz" # need alternate
+      "${CMAKE_CURRENT_SOURCE_DIR}/Step1.tgz"
   URL_MD5 38c648e817339c356f6be00eeed79bd0
   CMAKE_ARGS -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR> -G ${CMAKE_GENERATOR} <SOURCE_DIR>
   INSTALL_COMMAND ""