From 689be6235e5be32e8ee8e37801dde1fb1c5add2a Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Thu, 8 Aug 2019 09:31:42 -0700
Subject: Generator: support per-language link library flag

This enables the use of MSVC and Swift on Windows in a single project.
MSVC uses no flag to indicate linked libraries while Swift uses `-l`.
Add support for a language specific link library flag which takes
precedence over the global `CMAKE_LINK_LIBRARY_FLAG` which preserves
compatibility with earlier releases.
---
 Help/manual/cmake-variables.7.rst               | 1 +
 Help/release/dev/per-lang-link-library-flag.rst | 7 +++++++
 Help/variable/CMAKE_LANG_LINK_LIBRARY_FLAG.rst  | 7 +++++++
 Modules/CMakeSwiftInformation.cmake             | 1 +
 Source/cmComputeLinkInformation.cxx             | 9 +++++++--
 5 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 Help/release/dev/per-lang-link-library-flag.rst
 create mode 100644 Help/variable/CMAKE_LANG_LINK_LIBRARY_FLAG.rst

diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 432d7fc..22ea877 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -383,6 +383,7 @@ Variables that Control the Build
    /variable/CMAKE_LANG_CPPCHECK
    /variable/CMAKE_LANG_CPPLINT
    /variable/CMAKE_LANG_INCLUDE_WHAT_YOU_USE
+   /variable/CMAKE_LANG_LINK_LIBRARY_FLAG
    /variable/CMAKE_LANG_VISIBILITY_PRESET
    /variable/CMAKE_LIBRARY_OUTPUT_DIRECTORY
    /variable/CMAKE_LIBRARY_OUTPUT_DIRECTORY_CONFIG
diff --git a/Help/release/dev/per-lang-link-library-flag.rst b/Help/release/dev/per-lang-link-library-flag.rst
new file mode 100644
index 0000000..ca1181d
--- /dev/null
+++ b/Help/release/dev/per-lang-link-library-flag.rst
@@ -0,0 +1,7 @@
+per-lang-link-library-flag
+--------------------------
+
+* The new :variable:`CMAKE_<LANG>_LINK_LIBRARY_FLAG` flag allows you to now
+  control the flag used to specify linking to a library on a per-language basis.
+  This is useful for mixed-language projects where the different drivers may use
+  different flags.
diff --git a/Help/variable/CMAKE_LANG_LINK_LIBRARY_FLAG.rst b/Help/variable/CMAKE_LANG_LINK_LIBRARY_FLAG.rst
new file mode 100644
index 0000000..d7bb0d8
--- /dev/null
+++ b/Help/variable/CMAKE_LANG_LINK_LIBRARY_FLAG.rst
@@ -0,0 +1,7 @@
+CMAKE_<LANG>_LINK_LIBRARY_FLAG
+------------------------------
+
+Flag to be used to link a library into a shared library or executable.
+
+This flag will be used to specify a library to link to a shared library or an
+executable for the specific language.  On most compilers this is ``-l``.
diff --git a/Modules/CMakeSwiftInformation.cmake b/Modules/CMakeSwiftInformation.cmake
index 54e441c..cb161a6 100644
--- a/Modules/CMakeSwiftInformation.cmake
+++ b/Modules/CMakeSwiftInformation.cmake
@@ -36,6 +36,7 @@ set(CMAKE_Swift_DEFINE_FLAG -D)
 set(CMAKE_Swift_FRAMEWORK_SEARCH_FLAG "-F ")
 set(CMAKE_Swift_LIBRARY_PATH_FLAG "-L ")
 set(CMAKE_Swift_LIBRARY_PATH_TERMINATOR "")
+set(CMAKE_Swift_LINK_LIBRARY_FLAG "-l")
 set(CMAKE_Swift_LINKER_WRAPPER_FLAG "-Xlinker" " ")
 set(CMAKE_Swift_RESPONSE_FILE_LINK_FLAG @)
 
diff --git a/Source/cmComputeLinkInformation.cxx b/Source/cmComputeLinkInformation.cxx
index 4aa18f2..0741f8b 100644
--- a/Source/cmComputeLinkInformation.cxx
+++ b/Source/cmComputeLinkInformation.cxx
@@ -285,8 +285,13 @@ cmComputeLinkInformation::cmComputeLinkInformation(
   }
 
   // Get options needed to link libraries.
-  this->LibLinkFlag =
-    this->Makefile->GetSafeDefinition("CMAKE_LINK_LIBRARY_FLAG");
+  if (const char* flag = this->Makefile->GetDefinition(
+        "CMAKE_" + this->LinkLanguage + "_LINK_LIBRARY_FLAG")) {
+    this->LibLinkFlag = flag;
+  } else {
+    this->LibLinkFlag =
+      this->Makefile->GetSafeDefinition("CMAKE_LINK_LIBRARY_FLAG");
+  }
   this->LibLinkFileFlag =
     this->Makefile->GetSafeDefinition("CMAKE_LINK_LIBRARY_FILE_FLAG");
   this->LibLinkSuffix =
-- 
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