[clang] 8fc5f07 - [clang][driver][darwin] use the deployment target version as the SDK version

[Alex Lorenz via cfe-commits]

Author: Alex Lorenz
Date: 2021-04-30T18:54:02-07:00
New Revision: 8fc5f07fc0aee95ff9f79e91035d115690177dc1

URL: https://github.com/llvm/llvm-project/commit/8fc5f07fc0aee95ff9f79e91035d115690177dc1
DIFF: https://github.com/llvm/llvm-project/commit/8fc5f07fc0aee95ff9f79e91035d115690177dc1.diff

LOG: [clang][driver][darwin] use the deployment target version as the SDK version
when passing -platform_version to the linker

The use of a valid SDK version is preferred over an empty SDK version
(0.0.0) as the system's runtime might expect the linked binary to contain
a valid SDK version in order for the binary to work correctly

rdar://66795188

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/Darwin.cpp
    clang/test/Driver/darwin-ld-platform-version-macos.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 177cfd60ffb36..5ccd2300afd39 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -2671,8 +2671,16 @@ void Darwin::addPlatformVersionArgs(const llvm::opt::ArgList &Args,
     VersionTuple SDKVersion = SDKInfo->getVersion().withoutBuild();
     CmdArgs.push_back(Args.MakeArgString(SDKVersion.getAsString()));
   } else {
-    // Use a blank SDK version if it's not present.
-    CmdArgs.push_back("0.0.0");
+    // Use an SDK version that's matching the deployment target if the SDK
+    // version is missing. This is preferred over an empty SDK version (0.0.0)
+    // as the system's runtime might expect the linked binary to contain a
+    // valid SDK version in order for the binary to work correctly. It's
+    // reasonable to use the deployment target version as a proxy for the
+    // SDK version because older SDKs don't guarantee support for deployment
+    // targets newer than the SDK versions, so that rules out using some
+    // predetermined older SDK version, which leaves the deployment target
+    // version as the only reasonable choice.
+    CmdArgs.push_back(Args.MakeArgString(TargetVersion.getAsString()));
   }
 }
 

diff  --git a/clang/test/Driver/darwin-ld-platform-version-macos.c b/clang/test/Driver/darwin-ld-platform-version-macos.c
index 5a2510acb6467..8778281925d6b 100644
--- a/clang/test/Driver/darwin-ld-platform-version-macos.c
+++ b/clang/test/Driver/darwin-ld-platform-version-macos.c
@@ -48,4 +48,7 @@
 // RUN: %clang -target x86_64-apple-macos10.13 -mlinker-version=520 \
 // RUN:   -### %t.o 2>&1 \
 // RUN:   | FileCheck --check-prefix=NOSDK %s
-// NOSDK: "-platform_version" "macos" "10.13.0" "0.0.0"
+// RUN: %clang -target x86_64-apple-darwin17 -mlinker-version=520 \
+// RUN:   -### %t.o 2>&1 \
+// RUN:   | FileCheck --check-prefix=NOSDK %s
+// NOSDK: "-platform_version" "macos" "10.13.0" "10.13.0"