ENH: Support full-path libs w/out valid names.

This change introduces policy CMP0008 to decide how to treat full path
libraries that do not appear to be valid library file names.  Such
libraries worked by accident in the VS IDE and Xcode generators with
CMake 2.4 and below.  We support them in CMake 2.6 by introducing this
policy.  See policy documentation added by this change for details.

1 files changed, 26 insertions, 0 deletions

diff --git a/Source/cmPolicies.cxx b/Source/cmPolicies.cxx
index 64caf25..1b9ab96 100644
--- a/Source/cmPolicies.cxx
+++ b/Source/cmPolicies.cxx
@@ -281,6 +281,32 @@ cmPolicies::cmPolicies()
     "The NEW behavior for this policy is to correctly count empty "
     "elements in a list. ",
     2,6,0, cmPolicies::WARN);
+
+  this->DefinePolicy(
+    CMP0008, "CMP0008",
+    "Libraries linked by full-path must have a valid library file name.",
+    "In CMake 2.4 and below it is possible to write code like\n"
+    "  target_link_libraries(myexe /full/path/to/somelib)\n"
+    "where \"somelib\" is supposed to be a valid library file name "
+    "such as \"libsomelib.a\" or \"somelib.lib\".  "
+    "For Makefile generators this produces an error at build time "
+    "because the dependency on the full path cannot be found.  "
+    "For VS IDE and Xcode generators this used to work by accident because "
+    "CMake would always split off the library directory and ask the "
+    "linker to search for the library by name (-lsomelib or somelib.lib).  "
+    "Despite the failure with Makefiles, some projects have code like this "
+    "and build only with VS and/or Xcode.  "
+    "This version of CMake prefers to pass the full path directly to the "
+    "native build tool, which will fail in this case because it does "
+    "not name a valid library file."
+    "\n"
+    "This policy determines what to do with full paths that do not appear "
+    "to name a valid library file.  "
+    "The OLD behavior for this policy is to split the library name from the "
+    "path and ask the linker to search for it.  "
+    "The NEW behavior for this policy is to trust the given path and "
+    "pass it directly to the native build tool unchanged.",
+    2,6,1, cmPolicies::WARN);
 }
 
 cmPolicies::~cmPolicies()