find_library: Allow custom lib suffix be used as find path

Add a new `CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` variable to allow use
of a custom suffix on `lib` directory names.  This is a more general
option than that added by commit v3.7.0-rc1~504^2 (Teach find_library
and find_package to search lib32 paths, 2016-06-10).  It allows the find
path to be more deterministic on custom setups.

See discussion in #10287 and #15994.

1 files changed, 15 insertions, 13 deletions

diff --git a/Source/cmFindLibraryCommand.cxx b/Source/cmFindLibraryCommand.cxx
index 2feedf3..c506d66 100644
--- a/Source/cmFindLibraryCommand.cxx
+++ b/Source/cmFindLibraryCommand.cxx
@@ -43,20 +43,22 @@ bool cmFindLibraryCommand::InitialPass(std::vector<std::string> const& argsIn,
     return true;
   }
 
-  if (this->Makefile->GetState()->GetGlobalPropertyAsBool(
-        "FIND_LIBRARY_USE_LIB32_PATHS")) {
-    // add special 32 bit paths if this is a 32 bit compile.
-    if (this->Makefile->PlatformIs32Bit()) {
-      this->AddArchitecturePaths("32");
-    }
+  // add custom lib<qual> paths instead of using fixed lib32 or lib64
+  if (const char* customLib = this->Makefile->GetDefinition(
+        "CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX")) {
+    this->AddArchitecturePaths(customLib);
   }
-
-  if (this->Makefile->GetState()->GetGlobalPropertyAsBool(
-        "FIND_LIBRARY_USE_LIB64_PATHS")) {
-    // add special 64 bit paths if this is a 64 bit compile.
-    if (this->Makefile->PlatformIs64Bit()) {
-      this->AddArchitecturePaths("64");
-    }
+  // add special 32 bit paths if this is a 32 bit compile.
+  else if (this->Makefile->PlatformIs32Bit() &&
+           this->Makefile->GetState()->GetGlobalPropertyAsBool(
+             "FIND_LIBRARY_USE_LIB32_PATHS")) {
+    this->AddArchitecturePaths("32");
+  }
+  // add special 64 bit paths if this is a 64 bit compile.
+  else if (this->Makefile->PlatformIs64Bit() &&
+           this->Makefile->GetState()->GetGlobalPropertyAsBool(
+             "FIND_LIBRARY_USE_LIB64_PATHS")) {
+    this->AddArchitecturePaths("64");
   }
 
   std::string library = this->FindLibrary();