external dep lib dir

implementations/Crafter.Build-External.cpp

@@ -269,7 +269,20 @@ ExternalBuildResult Crafter::BuildExternal(
     }
 
     if (dep.builder == ExternalBuilder::CMake) {
-        result.linkFlags.push_back(std::format("-L{}", fs::absolute(cmakeBuildDir).string()));
+        // Each search path gets both a -L (link-time) and a -Wl,-rpath
+        // (runtime-loader). The rpath stays embedded in the produced
+        // binary so it picks up shared deps from the cache without any
+        // LD_LIBRARY_PATH gymnastics. Static deps (.a) ignore the rpath
+        // harmlessly.
+        std::string buildDirAbs = fs::absolute(cmakeBuildDir).string();
+        result.linkFlags.push_back(std::format("-L{}", buildDirAbs));
+        result.linkFlags.push_back(std::format("-Wl,-rpath,{}", buildDirAbs));
+        for (const fs::path& libDir : dep.libDirs) {
+            fs::path full = libDir.is_absolute() ? libDir : cmakeBuildDir / libDir;
+            std::string fullAbs = fs::absolute(full).string();
+            result.linkFlags.push_back(std::format("-L{}", fullAbs));
+            result.linkFlags.push_back(std::format("-Wl,-rpath,{}", fullAbs));
+        }
         for (const std::string& lib : dep.libs) {
             result.linkFlags.push_back(std::format("-l{}", lib));
         }

interfaces/Crafter.Build-External.cppm

@@ -43,6 +43,13 @@ export namespace Crafter {
         ExternalBuilder builder = ExternalBuilder::None;
         std::vector<std::string> options;
         std::vector<fs::path> includeDirs;
+        // Extra library search paths (each becomes a -L flag), interpreted
+        // relative to the CMake build dir. Currently only honoured for
+        // ExternalBuilder::CMake. The CMake builder always adds its
+        // top-level build dir as a -L; libDirs is for projects (msquic,
+        // others) whose CMakeLists set LIBRARY_OUTPUT_DIRECTORY to a subdir
+        // of the build tree.
+        std::vector<fs::path> libDirs;
         std::vector<std::string> libs;
     };