[Build] Set rpath to load C shared objects on linux

Author: aciidgh

Fixtures/ClangModules/SwiftCMixed/Package.swift

@@ -2,5 +2,8 @@ import PackageDescription
 
 let package = Package(
     name: "SwiftCMixed",
-    targets: [Target(name: "SeaExec", dependencies: ["SeaLib"])]
+    targets: [
+        Target(name: "SeaExec", dependencies: ["SeaLib"]),
+        Target(name: "CExec", dependencies: ["SeaLib"])
+    ]
 )

Fixtures/ClangModules/SwiftCMixed/Sources/CExec/main.c

@@ -0,0 +1,7 @@
+#include "Foo.h"
+#include<stdio.h>
+
+int main() {
+    printf("%d", foo(5));
+    return 0;
+}

Sources/Build/Command.link(ClangModule).swift

@@ -33,6 +33,10 @@ extension Command {
 
         args += try ClangModuleBuildMetadata.basicArgs() + otherArgs
         args += ["-L\(prefix)"]
+        // Linux doesn't search executable directory for shared libs so embed runtime search path.
+      #if os(Linux)
+        args += ["-Xlinker", "-rpath=$ORIGIN"]
+      #endif
         args += linkFlags
         args += objects
 

Tests/Functional/ClangModuleTests.swift

@@ -40,8 +40,11 @@ class ClangModulesTestCase: XCTestCase {
             XCTAssertFileExists(prefix, ".build", "debug", "SeaLib".soname)
             let exec = ".build/debug/SeaExec"
             XCTAssertFileExists(prefix, exec)
-            let output = try popen([Path.join(prefix, exec)])
+            var output = try popen([Path.join(prefix, exec)])
             XCTAssertEqual(output, "a = 5\n")
+            let cExec = ".build/debug/CExec"
+            output = try popen([Path.join(prefix, cExec)])
+            XCTAssertEqual(output, "5")
         }
     }
 

Tests/Xcodeproj/FunctionalTests.swift

@@ -41,6 +41,7 @@ class FunctionalTests: XCTestCase {
             let build = Path.join(prefix, "build", "Debug")
             XCTAssertDirectoryExists(build, "SeaLib.framework")
             XCTAssertFileExists(build, "SeaExec")
+            XCTAssertFileExists(build, "CExec")
         }
     }