From 369c48ee437263a9702c8725f6e73bc4b9d0fe16 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Sun, 11 Aug 2019 18:36:06 -0700
Subject: Swift: honour `-swift-version` in Ninja generator

Swift has supported `CMAKE_Swift_LANGUAGE_VERSION` and
`Swift_LANGUAGE_VERSION` but didn't apply that to Ninja generated
targets.  Consider the property when calculating the flags.
---
 Help/manual/cmake-properties.7.rst       |  1 +
 Help/prop_tgt/Swift_LANGUAGE_VERSION.rst |  6 ++++++
 Source/cmLocalGenerator.cxx              | 11 +++++++++++
 Source/cmTarget.cxx                      |  1 +
 4 files changed, 19 insertions(+)
 create mode 100644 Help/prop_tgt/Swift_LANGUAGE_VERSION.rst

diff --git a/Help/manual/cmake-properties.7.rst b/Help/manual/cmake-properties.7.rst
index 62d23c7..def9700 100644
--- a/Help/manual/cmake-properties.7.rst
+++ b/Help/manual/cmake-properties.7.rst
@@ -316,6 +316,7 @@ Properties on Targets
    /prop_tgt/STATIC_LIBRARY_OPTIONS
    /prop_tgt/SUFFIX
    /prop_tgt/Swift_DEPENDENCIES_FILE
+   /prop_tgt/Swift_LANGUAGE_VERSION
    /prop_tgt/Swift_MODULE_DIRECTORY
    /prop_tgt/Swift_MODULE_NAME
    /prop_tgt/TYPE
diff --git a/Help/prop_tgt/Swift_LANGUAGE_VERSION.rst b/Help/prop_tgt/Swift_LANGUAGE_VERSION.rst
new file mode 100644
index 0000000..7579447
--- /dev/null
+++ b/Help/prop_tgt/Swift_LANGUAGE_VERSION.rst
@@ -0,0 +1,6 @@
+Swift_LANGUAGE_VERSION
+----------------------
+
+This property sets the language version for the Swift sources in the target.  If
+one is not specified, it will default to ``<CMAKE_Swift_LANGUAGE_VERSION>`` if
+specified, otherwise it is the latest version supported by the compiler.
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 1827a42..5ee1717 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -1566,6 +1566,17 @@ void cmLocalGenerator::AddLanguageFlags(std::string& flags,
   this->AddConfigVariableFlags(flags, cmStrCat("CMAKE_", lang, "_FLAGS"),
                                config);
 
+  if (lang == "Swift") {
+    if (const char* v = target->GetProperty("Swift_LANGUAGE_VERSION")) {
+      if (cmSystemTools::VersionCompare(
+            cmSystemTools::OP_GREATER_EQUAL,
+            this->Makefile->GetDefinition("CMAKE_Swift_COMPILER_VERSION"),
+            "4.2")) {
+        this->AppendFlags(flags, "-swift-version " + std::string(v));
+      }
+    }
+  }
+
   // Add MSVC runtime library flags.  This is activated by the presence
   // of a default selection whether or not it is overridden by a property.
   const char* msvcRuntimeLibraryDefault =
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index bc1b9de..e3e175a 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -347,6 +347,7 @@ cmTarget::cmTarget(std::string const& name, cmStateEnums::TargetType type,
     initProp("LINK_SEARCH_START_STATIC");
     initProp("LINK_SEARCH_END_STATIC");
     initProp("FOLDER");
+    initProp("Swift_LANGUAGE_VERSION");
     initProp("Swift_MODULE_DIRECTORY");
     initProp("VS_JUST_MY_CODE_DEBUGGING");
 #ifdef __APPLE__
-- 
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