Add target property LINK_SEARCH_START_STATIC to aid static linking

Commit afd7d4ca (Add target property LINK_SEARCH_END_STATIC, 2008-01-31)
defined a property to ensure that static runtime libraries get selected.
Add a property to specify that all libraries whose type is unknown, such
as "-lm", should be assumed static.  Furthermore it assumes that an
option such as "-static" is also used so that no initial -Bstatic is
needed.

2 files changed, 26 insertions, 11 deletions

diff --git a/Source/cmComputeLinkInformation.cxx b/Source/cmComputeLinkInformation.cxx
index d53200c..e3c33a2 100644
--- a/Source/cmComputeLinkInformation.cxx
+++ b/Source/cmComputeLinkInformation.cxx
@@ -817,9 +817,9 @@ void cmComputeLinkInformation::ComputeLinkTypeInfo()
     this->SharedLinkTypeFlag = shared_link_type_flag;
     }
 
-  // TODO: Lookup the starting link type from the target (is it being
-  // linked statically?).
-  this->StartLinkType = LinkShared;
+  // Lookup the starting link type from the target (linked statically?).
+  const char* lss = this->Target->GetProperty("LINK_SEARCH_START_STATIC");
+  this->StartLinkType = cmSystemTools::IsOn(lss)? LinkStatic : LinkShared;
   this->CurrentLinkType = this->StartLinkType;
 }
 
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 75ff712..0ca46c4 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -487,17 +487,32 @@ void cmTarget::DefineProperties(cmake *cm)
      "Per-configuration linker flags for a target.",
      "This is the configuration-specific version of LINK_FLAGS.");
 
+#define CM_LINK_SEARCH_SUMMARY \
+  "Some linkers support switches such as -Bstatic and -Bdynamic " \
+  "to determine whether to use static or shared libraries for -lXXX " \
+  "options.  CMake uses these options to set the link type for " \
+  "libraries whose full paths are not known or (in some cases) are in " \
+  "implicit link directories for the platform.  "
+
+  cm->DefineProperty
+    ("LINK_SEARCH_START_STATIC", cmProperty::TARGET,
+     "Assume the linker looks for static libraries by default.",
+     CM_LINK_SEARCH_SUMMARY
+     "By default the linker search type is assumed to be -Bdynamic at "
+     "the beginning of the library list.  This property switches the "
+     "assumption to -Bstatic.  It is intended for use when linking an "
+     "executable statically (e.g. with the GNU -static option).  "
+     "See also LINK_SEARCH_END_STATIC.");
+
   cm->DefineProperty
     ("LINK_SEARCH_END_STATIC", cmProperty::TARGET,
      "End a link line such that static system libraries are used.",
-     "Some linkers support switches such as -Bstatic and -Bdynamic "
-     "to determine whether to use static or shared libraries for -lXXX "
-     "options.  CMake uses these options to set the link type for "
-     "libraries whose full paths are not known or (in some cases) are in "
-     "implicit link directories for the platform.  By default the "
-     "linker search type is left at -Bdynamic by the end of the library "
-     "list.  This property switches the final linker search type to "
-     "-Bstatic.");
+     CM_LINK_SEARCH_SUMMARY
+     "By default CMake adds an option at the end of the library list (if "
+     "necessary) to set the linker search type back to its starting type.  "
+     "This property switches the final linker search type to -Bstatic "
+     "regardless of how it started.  "
+     "See also LINK_SEARCH_START_STATIC.");
 
   cm->DefineProperty
     ("LINKER_LANGUAGE", cmProperty::TARGET,