build: PkgLinkExtern

internal/build/build.go

@@ -167,12 +167,12 @@ func buildAllPkgs(prog llssa.Program, initial []*packages.Package, mode Mode, ve
 	}
 	for _, aPkg := range pkgs {
 		pkg := aPkg.Package
-		switch kind := cl.PkgKindOf(pkg.Types); kind {
+		switch kind, param := cl.PkgKindOf(pkg.Types); kind {
 		case cl.PkgDeclOnly:
 			// skip packages that only contain declarations
 			// and set no export file
 			pkg.ExportFile = ""
-		case cl.PkgLinkIR: // cl.PkgLinkBitCode:
+		case cl.PkgLinkIR:
 			// skip packages that don't need to be compiled but need to be linked
 			pkgPath := pkg.PkgPath
 			if isPkgInLLGo(pkgPath) {
@@ -180,6 +180,15 @@ func buildAllPkgs(prog llssa.Program, initial []*packages.Package, mode Mode, ve
 			} else {
 				panic("todo")
 			}
+		case cl.PkgLinkExtern:
+			// skip packages that don't need to be compiled but need to be linked with external library
+			linkFile := os.ExpandEnv(strings.TrimSpace(param))
+			dir, lib := filepath.Split(linkFile)
+			command := " -l " + lib
+			if dir != "" {
+				command += " -L " + dir
+			}
+			pkg.ExportFile = command
 		default:
 			buildPkg(prog, aPkg, mode, verbose)
 			if prog.NeedRuntime() {