Support building shared libraries or modules without soname (#13155)

Add a boolean target property NO_SONAME which may be used to disable
soname for the specified shared library or module even if the platform
supports it.  This property should be useful for private shared
libraries or various plugins which live in private directories and have
not been designed to be found or loaded globally.

Replace references to <CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG> and
hard-coded -install_name flags with a conditional <SONAME_FLAG> which is
expanded to the value of the CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG
definition as long as soname supports is enabled for the target in
question.  Keep expanding CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG in
rules in case third party projects still use it.  Such projects would
not yet use NO_SONAME so the adjacent <TARGET_SONAME> will always be
expanded.  Make <TARGET_INSTALLNAME_DIR> NO_SONAME aware as well.  Since
-install_name is soname on OS X, this should not be a problem if this
variable is expanded only if soname is enabled.

The Ninja generator performs rule variable substitution only once
globally per rule to put its own placeholders.  Final substitution is
performed by ninja at build time.  Therefore we cannot conditionally
replace the soname placeholders on a per-target basis.  Rather than
omitting $SONAME from rules.ninja, simply do not write its contents for
targets which have NO_SONAME.  Since 3 variables are affected by
NO_SONAME ($SONAME, $SONAME_FLAG, $INSTALLNAME_DIR), set them only if
soname is enabled.

1 files changed, 26 insertions, 13 deletions

diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index cfa9976..4789197 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -823,6 +823,19 @@ void cmTarget::DefineProperties(cmake *cm)
      "CMAKE_SKIP_BUILD_RPATH if it is set when a target is created.");
 
   cm->DefineProperty
+    ("NO_SONAME", cmProperty::TARGET,
+     "Whether to set \"soname\" when linking a shared library or module.",
+     "Enable this boolean property if a generated shared library or module "
+     "should not have \"soname\" set. Default is to set \"soname\" on all "
+     "shared libraries and modules as long as the platform supports it. "
+     "Generally, use this property only for leaf private libraries or "
+     "plugins. If you use it on normal shared libraries which other targets "
+     "link against, on some platforms a linker will insert a full path to "
+     "the library (as specified at link time) into the dynamic section of "
+     "the dependant binary. Therefore, once installed, dynamic linker may "
+     "eventually fail to locate the library for the binary.");
+
+  cm->DefineProperty
     ("SOVERSION", cmProperty::TARGET,
      "What version number is this target.",
      "For shared libraries VERSION and SOVERSION can be used to specify "
@@ -831,6 +844,7 @@ void cmTarget::DefineProperties(cmake *cm)
      "supports symlinks and the linker supports so-names. "
      "If only one of both is specified the missing is assumed to have "
      "the same version number. "
+     "SOVERSION is ignored if NO_SONAME property is set. "
      "For shared libraries and executables on Windows the VERSION "
      "attribute is parsed to extract a \"major.minor\" version number. "
      "These numbers are used as the image version of the binary. ");
@@ -2995,6 +3009,17 @@ std::string cmTarget::GetPDBName(const char* config)
 }
 
 //----------------------------------------------------------------------------
+bool cmTarget::HasSOName(const char* config)
+{
+  // soname is supported only for shared libraries and modules,
+  // and then only when the platform supports an soname flag.
+  return ((this->GetType() == cmTarget::SHARED_LIBRARY ||
+           this->GetType() == cmTarget::MODULE_LIBRARY) &&
+          !this->GetPropertyAsBool("NO_SONAME") &&
+          this->Makefile->GetSONameFlag(this->GetLinkerLanguage(config)));
+}
+
+//----------------------------------------------------------------------------
 std::string cmTarget::GetSOName(const char* config)
 {
   if(this->IsImported())
@@ -3327,22 +3352,10 @@ void cmTarget::GetLibraryNames(std::string& name,
     return;
     }
 
-  // Construct the name of the soname flag variable for this language.
-  const char* ll = this->GetLinkerLanguage(config);
-  std::string sonameFlag = "CMAKE_SHARED_LIBRARY_SONAME";
-  if(ll)
-    {
-    sonameFlag += "_";
-    sonameFlag += ll;
-    }
-  sonameFlag += "_FLAG";
-
   // Check for library version properties.
   const char* version = this->GetProperty("VERSION");
   const char* soversion = this->GetProperty("SOVERSION");
-  if((this->GetType() != cmTarget::SHARED_LIBRARY &&
-      this->GetType() != cmTarget::MODULE_LIBRARY) ||
-     !this->Makefile->GetDefinition(sonameFlag.c_str()) ||
+  if(!this->HasSOName(config) ||
      this->IsFrameworkOnApple())
     {
     // Versioning is supported only for shared libraries and modules,