diff options
| -rw-r--r-- | libbuild2/rule.cxx | 78 |
1 files changed, 66 insertions, 12 deletions
diff --git a/libbuild2/rule.cxx b/libbuild2/rule.cxx index 7286c63..ac45305 100644 --- a/libbuild2/rule.cxx +++ b/libbuild2/rule.cxx @@ -654,6 +654,9 @@ namespace build2 // @@ Need to unlock phase while waiting. if (impl == nullptr) { + using create_function = cxx_rule* (const location&); + using load_function = create_function* (); + dir_path pd (rs.out_path () / rs.root_extra->build_dir / recipes_build_dir /= id); @@ -727,16 +730,48 @@ namespace build2 // ofs << "namespace build2" << '\n' << "{" << '\n' - << "class rule_" << id << ": public cxx_rule" << '\n' + << '\n'; + + // If we want the user to be able to supply a custom constuctor, + // then we have to give the class a predictable name (i.e., we + // cannot use id as part of its name) and put it into an anonymous + // namespace. One clever idea is to call the class `constructor` but + // the name could also be used for a custom destructor (still could + // work) or for name qualification (would definitely look bizarre). + // + // In this light the most natural name is probable `rule`. The issue + // is we already have this name in the build2 namespace (and its our + // indirect base). In fact, any name that we choose could in the + // future conflict with something in that namespace so maybe it + // makes sense to bite the bullet and pick a name that is least + // likely to be used by the user directly (can always use cxx_rule + // instead). + // + ofs << "namespace" << '\n' + << "{" << '\n' + << "class rule: public cxx_rule" << '\n' << "{" << '\n' - << "public:" << '\n'; + << "public:" << '\n' + << '\n'; - // Inherit base constructor. This way the user may provide their - // own but don't have to. + // Inherit base constructor. This way the user may provide their own + // but don't have to. // ofs << " using cxx_rule::cxx_rule;" << '\n' << '\n'; + // An extern "C" function cannot throw which can happen in case of a + // user-defined constructor. So we need an extra level of + // indirection. We incorporate id to make sure it doesn't conflict + // with anything user-defined. + // + ofs << " static cxx_rule*" << '\n' + << " create_" << id << " (const location& l)" << '\n' + << " {" << '\n' + << " return new rule (l);" << '\n' + << " }" << '\n' + << '\n'; + // Use the #line directive to point diagnostics to the code in the // buildfile. Note that there is no easy way to restore things to // point back to the source file (other than another #line with a @@ -754,18 +789,27 @@ namespace build2 // ofs << code << "};" << '\n' + << '\n'; + + // Add an alias that we can use unambiguously in the load function. + // + ofs << "using rule_" << id << " = rule;" << '\n' << "}" << '\n' << '\n'; + // Entry point. + // ofs << "extern \"C\"" << '\n' << "#ifdef _WIN32" << '\n' << "__declspec(dllexport)" << '\n' << "#endif" << '\n' - << "build2::cxx_rule*" << '\n' - << sym << " (const build2::location* l)" << '\n' + << "cxx_rule* (*" << sym << " ()) (const location&)" << '\n' << "{" << '\n' - << "return new build2::rule_" << id << " (*l);" << '\n' - << "}" << '\n'; + << " return &rule_" << id << "::create_" << id << ";" << '\n' + << "}" << '\n' + << '\n'; + + ofs << "}" << '\n'; ofs.close (); @@ -827,6 +871,8 @@ namespace build2 string err; pair<void*, void*> hs (load_module_library (lib, sym, err)); + // These normally shouldn't happen unless something is seriously broken. + // if (hs.first == nullptr) fail (loc) << "unable to load recipe library " << lib << ": " << err; @@ -834,11 +880,19 @@ namespace build2 fail (loc) << "unable to lookup " << sym << " in recipe library " << lib << ": " << err; - // @@ TODO: this function cannot throw (extern C). - // - auto f (function_cast<cxx_rule* (*) (const location*)> (hs.second)); + { + auto df = make_diag_frame ( + [this](const diag_record& dr) + { + if (verb != 0) + dr << info (loc) << "while initializing ad hoc recipe"; + }); - impl.reset (f (&loc)); + load_function* lf (function_cast<load_function*> (hs.second)); + create_function* cf (lf ()); + + impl.reset (cf (loc)); + } } return impl->match (a, t, hint); |