root/root-make-dyld-based-library-search-behavior-default.patch

From 6ae602bba7d33c900a117c9de0187ab5a28e14b8 Mon Sep 17 00:00:00 2001
From: Vassil Vassilev <v.g.vassilev@gmail.com>
Date: Mon, 21 Mar 2022 22:16:54 +0000
Subject: [PATCH] Make the dyld-based library search behavior default for
 non-modules.

The dyld-based system was developed in the context on C++ modules but it turned
into a modules-agnostic feature. Instead of having to maintain more code, we
should rely on it even for non-modules build of ROOT.
---
 core/metacling/src/TCling.cxx | 109 +++-------------------------------
 1 file changed, 8 insertions(+), 101 deletions(-)

diff --git a/core/metacling/src/TCling.cxx b/core/metacling/src/TCling.cxx
index dec399cf2b..3eae1c8570 100644
--- a/core/metacling/src/TCling.cxx
+++ b/core/metacling/src/TCling.cxx
@@ -6501,14 +6501,18 @@ bool TCling::LibraryLoadingFailed(const std::string& errmessage, const std::stri
    return false;
 }
 
-static void* LazyFunctionCreatorAutoloadForModule(const std::string &mangled_name,
-                                                  const cling::DynamicLibraryManager &DLM) {
+////////////////////////////////////////////////////////////////////////////////
+/// Autoload a library based on a missing symbol.
+
+void* TCling::LazyFunctionCreatorAutoload(const std::string& mangled_name) {
+
+   const cling::DynamicLibraryManager &DLM = *GetInterpreterImpl()->getDynamicLibraryManager();
    R__LOCKGUARD(gInterpreterMutex);
 
    auto LibLoader = [](const std::string& LibName) -> bool {
      if (gSystem->Load(LibName.c_str(), "", false) < 0) {
-       Error("TCling__LazyFunctionCreatorAutoloadForModule",
-             "Failed to load library %s", LibName.c_str());
+        ::Error("TCling__LazyFunctionCreatorAutoloadForModule",
+                "Failed to load library %s", LibName.c_str());
        return false;
      }
      return true; //success.
@@ -6536,103 +6540,6 @@ static void* LazyFunctionCreatorAutoloadForModule(const std::string &mangled_nam
       return nullptr;
 
    return llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(mangled_name);
-
-}
-
-////////////////////////////////////////////////////////////////////////////////
-/// Autoload a library based on a missing symbol.
-
-void* TCling::LazyFunctionCreatorAutoload(const std::string& mangled_name) {
-   if (fCxxModulesEnabled)
-      return LazyFunctionCreatorAutoloadForModule(mangled_name,
-                                                  *GetInterpreterImpl()->getDynamicLibraryManager());
-
-   // First see whether the symbol is in the library that we are currently
-   // loading. It will have access to the symbols of its dependent libraries,
-   // thus checking "back()" is sufficient.
-   if (!fRegisterModuleDyLibs.empty()) {
-      if (void* addr = dlsym(fRegisterModuleDyLibs.back(),
-                             mangled_name.c_str())) {
-         return addr;
-      }
-   }
-
-   int err = 0;
-   char* demangled_name_c = TClassEdit::DemangleName(mangled_name.c_str(), err);
-   if (err) {
-      return 0;
-   }
-
-   std::string name(demangled_name_c);
-   free(demangled_name_c);
-
-   //fprintf(stderr, "demangled name: '%s'\n", demangled_name);
-   //
-   //  Separate out the class or namespace part of the
-   //  function name.
-   //
-
-   std::string::size_type pos = name.find("__thiscall ");
-   if (pos != std::string::npos) {
-      name.erase(0, pos + sizeof("__thiscall ")-1);
-   }
-   pos = name.find("__cdecl ");
-   if (pos != std::string::npos) {
-      name.erase(0, pos + sizeof("__cdecl ")-1);
-   }
-   if (!strncmp(name.c_str(), "typeinfo for ", sizeof("typeinfo for ")-1)) {
-      name.erase(0, sizeof("typeinfo for ")-1);
-   } else if (!strncmp(name.c_str(), "vtable for ", sizeof("vtable for ")-1)) {
-      name.erase(0, sizeof("vtable for ")-1);
-   } else if (!strncmp(name.c_str(), "operator", sizeof("operator")-1)
-              && !isalnum(name[sizeof("operator")])) {
-     // operator...(A, B) - let's try with A!
-     name.erase(0, sizeof("operator")-1);
-     pos = name.rfind('(');
-     if (pos != std::string::npos) {
-       name.erase(0, pos + 1);
-       pos = name.find(",");
-       if (pos != std::string::npos) {
-         // remove next arg up to end, leaving only the first argument type.
-         name.erase(pos);
-       }
-       pos = name.rfind(" const");
-       if (pos != std::string::npos) {
-         name.erase(pos, strlen(" const"));
-       }
-       while (!name.empty() && strchr("&*", name.back()))
-         name.erase(name.length() - 1);
-     }
-   } else {
-      TClassEdit::FunctionSplitInfo fsi;
-      TClassEdit::SplitFunction(name, fsi);
-      name = fsi.fScopeName;
-   }
-   //fprintf(stderr, "name: '%s'\n", name.c_str());
-   // Now we have the class or namespace name, so do the lookup.
-   TString libs = GetClassSharedLibs(name.c_str());
-   if (libs.IsNull()) {
-      // Not found in the map, all done.
-      return 0;
-   }
-   //fprintf(stderr, "library: %s\n", iter->second.c_str());
-   // Now we have the name of the libraries to load, so load them.
-
-   TString lib;
-   Ssiz_t posLib = 0;
-   while (libs.Tokenize(lib, posLib)) {
-      if (gSystem->Load(lib, "", kFALSE /*system*/) < 0) {
-         // The library load failed, all done.
-         //fprintf(stderr, "load failed: %s\n", errmsg.c_str());
-         return 0;
-      }
-   }
-
-   //fprintf(stderr, "load succeeded.\n");
-   // Get the address of the function being called.
-   void* addr = llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(mangled_name.c_str());
-   //fprintf(stderr, "addr: %016lx\n", reinterpret_cast<unsigned long>(addr));
-   return addr;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-- 
2.35.1