Tests: Improve GeneratorExpression SHELL_PATH case robustness on MSYS 1.0

Since commit ca6ba3fee5 (Genex: Add a SHELL_PATH expression, 2015-09-24,
v3.4.0-rc1~37^2) and commit 21da25d2a8 (Tests: Generalize
GeneratorExpression MSYS path conversion workaround, 2019-03-11,
v3.15.0-rc1~407^2~1) we use a prefix string to prevent the MSYS 1.0
shell from converting absolute paths of the form `/c/...` to
windows-style paths.  In the newer `mingw.osdn.io` distribution of MSYS
1.0, the `bash` shell now also converts paths that appear after `:`.
We have no way to add a prefix string in that context, so perform the
test's check of the `SHELL_PATH` genex value at generate time instead.

1 files changed, 7 insertions, 2 deletions

diff --git a/Tests/GeneratorExpression/check-part4.cmake b/Tests/GeneratorExpression/check-part4.cmake
index a7e0944..28f3699 100644
--- a/Tests/GeneratorExpression/check-part4.cmake
+++ b/Tests/GeneratorExpression/check-part4.cmake
@@ -16,8 +16,13 @@ else()
   check(test_shell_path [[/shell/path]])
 endif()
 if(WIN32)
-  if(CMAKE_GENERATOR STREQUAL "MSYS Makefiles" AND NOT msys1_prefix)
-    check(test_shell_path2 [[/c/shell/path:/d/another/path]])
+  if(CMAKE_GENERATOR STREQUAL "MSYS Makefiles")
+    if(msys1_prefix)
+      # The comparison was done at generate time with the STREQUAL genex.
+      check(test_shell_path2 [[1]])
+    else()
+      check(test_shell_path2 [[/c/shell/path:/d/another/path]])
+    endif()
   elseif(CMAKE_GENERATOR STREQUAL "Unix Makefiles")
     check(test_shell_path2 [[c:/shell/path;d:/another/path]])
   else()