Rename rule-adhoc-* to adhoc-rule-*

1 files changed, 665 insertions, 0 deletions

diff --git a/libbuild2/adhoc-rule-cxx.cxx b/libbuild2/adhoc-rule-cxx.cxx
new file mode 100644
index 0000000..8d9b788
--- /dev/null
+++ b/libbuild2/adhoc-rule-cxx.cxx
@@ -0,0 +1,665 @@
+// file      : libbuild2/adhoc-rule-cxx.cxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#include <libbuild2/adhoc-rule-cxx.hxx>
+
+#include <libbutl/filesystem.mxx> // file_time()
+
+#include <libbuild2/file.hxx>
+#include <libbuild2/scope.hxx>
+#include <libbuild2/target.hxx>
+#include <libbuild2/context.hxx>
+#include <libbuild2/algorithm.hxx>
+#include <libbuild2/diagnostics.hxx>
+
+using namespace butl;
+
+namespace build2
+{
+  // cxx_rule_v1
+  //
+  bool cxx_rule_v1::
+  match (action, target&, const string&) const
+  {
+    return true;
+  }
+
+  // adhoc_cxx_rule
+  //
+  adhoc_cxx_rule::
+  adhoc_cxx_rule (const location& l, size_t b, uint64_t v, optional<string> s)
+      : adhoc_rule ("<ad hoc c++ recipe>", l, b),
+        version (v),
+        separator (move (s)),
+        impl (nullptr)
+  {
+    if (v != 1)
+      fail (l) << "unsupported c++ recipe version " << v;
+  }
+
+  bool adhoc_cxx_rule::
+  recipe_text (context&, const target&, string&& t, attributes&)
+  {
+    code = move (t);
+    return true;
+  }
+
+  adhoc_cxx_rule::
+  ~adhoc_cxx_rule ()
+  {
+    delete impl.load (memory_order_relaxed); // Serial execution.
+  }
+
+  void adhoc_cxx_rule::
+  dump_text (ostream& os, string& ind) const
+  {
+    // @@ TODO: indentation is multi-line recipes is off (would need to insert
+    //          indentation after every newline).
+    //
+    os << ind << string (braces, '{') << " c++ " << version << endl
+       << ind << code
+       << ind << string (braces, '}');
+  }
+
+#if defined(BUILD2_BOOTSTRAP) || defined(LIBBUILD2_STATIC_BUILD)
+  bool adhoc_cxx_rule::
+  match (action, target&, const string&) const
+  {
+    // Note that we wait until match() (instead of, say, failing in the
+    // parser) to allow the presence of ad hoc C++ recipes for other
+    // operations.
+    //
+    fail (loc) << "ad hoc c++ recipe" <<
+#ifdef BUILD2_BOOTSTRAP
+      info << "running bootstrap build system" << endf;
+#else
+      info << "running statically-linked build system" << endf;
+#endif
+  }
+
+#else
+
+  // From module.cxx.
+  //
+  void
+  create_module_context (context&, const location&);
+
+  const target&
+  update_in_module_context (context&, const scope&, names tgt,
+                            const location&, const path& bf);
+
+  pair<void*, void*>
+  load_module_library (const path& lib, const string& sym, string& err);
+
+  bool adhoc_cxx_rule::
+  match (action a, target& t, const string& hint) const
+  {
+    tracer trace ("adhoc_cxx_rule::match");
+
+    context& ctx (t.ctx);
+    const scope& rs (t.root_scope ());
+
+    // The plan is to reduce this to the build system module case as much as
+    // possible. Specifically, we switch to the load phase, create a module-
+    // like library with the recipe text as a rule implementation, then build
+    // and load it.
+    //
+    // Since the recipe can be shared among multiple targets, several threads
+    // can all be trying to do this in parallel.
+    //
+    // We use the relaxed memory order here because any change must go through
+    // the serial load phase. In other words, all we need here is atomicity
+    // with ordering/visibility provided by the phase mutex.
+    //
+    cxx_rule* impl (this->impl.load (memory_order_relaxed));
+
+    while (impl == nullptr) // Breakout loop.
+    {
+      // Switch the phase to (serial) load and re-check.
+      //
+      phase_switch ps (ctx, run_phase::load);
+
+      if ((impl = this->impl.load (memory_order_relaxed)) != nullptr)
+        break;
+
+      using create_function = cxx_rule_v1* (const location&, target_state);
+      using load_function = create_function* ();
+
+      // The only way to guarantee that the name of our module matches its
+      // implementation is to based the name on the implementation hash (plus
+      // the language, in case we support other compiled implementations in
+      // the future).
+      //
+      // Unfortunately, this means we will be creating a new project (and
+      // leaving behind the old one as garbage) for every change to the
+      // recipe. On the other hand, if the recipe is moved around unchanged,
+      // we will reuse the same project. In fact, two different recipes (e.g.,
+      // in different buildfiles) with the same text will share the project.
+      //
+      // The fact that we don't incorporate the recipe location into the hash
+      // but include it in the source (in the form of the #line directive; see
+      // below) has its own problems. If we do nothing extra here, then if a
+      // "moved" but otherwise unchanged recipe is updated (for example,
+      // because of changes in the build system core), then we may end up with
+      // bogus location in the diagnostics.
+      //
+      // The straightforward solution would be to just update the location in
+      // the source code if it has changed. This, however, will lead to
+      // unnecessary and probably surprising recompilations since any line
+      // count change before the recipe will trigger this update. One key
+      // observation here is that we need accurate location information only
+      // if we are going to recompile the recipe but the change to location
+      // itself does not render the recipe out of date. So what we going to do
+      // is factor the location information into its own small header and then
+      // keep it up-to-date without changing its modification time.
+      //
+      // This works well if the project is not shared by multiple recipes.
+      // However, if we have recipes in several buildfiles with identical
+      // text, then the location information may end up yo-yo'ing depending on
+      // which recipe got here first.
+      //
+      // There doesn't seem to be much we can do about it without incurring
+      // other drawbacks/overheads. So the answer is for the user to use an ad
+      // hoc rule with the common implementation instead of a bunch of
+      // duplicate recipes.
+      //
+      string id;
+      {
+        sha256 cs;
+        cs.append ("c++");
+        cs.append (separator ? *separator : "");
+        cs.append (code);
+        id = cs.abbreviated_string (12);
+      }
+
+      dir_path pd (rs.out_path () /
+                   rs.root_extra->build_build_dir /
+                   recipes_build_dir /= id);
+
+      path bf (pd / std_buildfile_file);
+
+      string sym ("load_" + id);
+
+      // Check whether the file exists and its last line matches the specified
+      // signature.
+      //
+      // Note: we use the last instead of the first line for extra protection
+      // against incomplete writes.
+      //
+      auto check_sig = [] (const path& f, const string& s) -> bool
+      {
+        try
+        {
+          if (!file_exists (f))
+            return false;
+
+          ifdstream ifs (f);
+
+          string l;
+          while (ifs.peek () != ifdstream::traits_type::eof ())
+            getline (ifs, l);
+
+          return l == s;
+        }
+        catch (const io_error& e)
+        {
+          fail << "unable to read " << f << ": " << e << endf;
+        }
+        catch (const system_error& e)
+        {
+          fail << "unable to access " << f << ": " << e << endf;
+        }
+      };
+
+      // Calculate (and cache) the global/local fragments split.
+      //
+      struct fragments
+      {
+        size_t   global_p; // Start position.
+        size_t   global_n; // Length (0 if no global fragment).
+        location global_l; // Position.
+
+        size_t   local_p;
+        size_t   local_n;
+        location local_l;
+      };
+
+      auto split = [this, f = optional<fragments> ()] () mutable ->
+        const fragments&
+      {
+        if (f)
+          return *f;
+
+        // Note that the code starts from the next line thus +1.
+        //
+        location gl (loc.file, loc.line + 1, 1);
+
+        if (!separator)
+        {
+          f = fragments {0, 0, location (), 0, code.size (), gl};
+          return *f;
+        }
+
+        // Iterate over lines (keeping track of the current line) looking
+        // for the separator.
+        //
+        uint64_t l (gl.line);
+        for (size_t b (0), e (b), n (code.size ()); b < n; b = e + 1, l++)
+        {
+          if ((e = code.find ('\n', b)) == string::npos)
+            e = n;
+
+          // Trim the line.
+          //
+          size_t tb (b), te (e);
+          auto ws = [] (char c) {return c == ' ' || c == '\t' || c == '\r';};
+          for (; tb != te && ws (code[tb    ]); ++tb) ;
+          for (; te != tb && ws (code[te - 1]); --te) ;
+
+          // text << "'" << string (code, tb, te - tb) << "'";
+
+          if (code.compare (tb, te - tb, *separator) == 0)
+          {
+            // End the global fragment at the previous newline and start the
+            // local fragment at the beginning of the next line.
+            //
+            location ll (loc.file, l + 1, 1);
+
+            if (++e >= n)
+              fail (ll) << "empty c++ recipe local fragment";
+
+            f = fragments {0, b, gl, e, n - e, ll};
+            return *f;
+          }
+        }
+
+        fail (loc) << "c++ recipe fragment separator '" << *separator
+                   << "' not found" << endf;
+      };
+
+      bool nested (ctx.module_context == &ctx);
+
+      // Create the build context if necessary.
+      //
+      if (ctx.module_context == nullptr)
+      {
+        if (!ctx.module_context_storage)
+          fail (loc) << "unable to update ad hoc recipe for target " << t <<
+            info << "building of ad hoc recipes is disabled";
+
+        create_module_context (ctx, loc);
+      }
+
+      // "Switch" to the module context.
+      //
+      context& ctx (*t.ctx.module_context);
+
+      const uint16_t verbosity (3); // Project creation command verbosity.
+
+      // Project and location signatures.
+      //
+      // Specifically, we update the project version when changing anything
+      // which would make the already existing projects unusable.
+      //
+      const string& lf (!loc.file.path.empty ()
+                        ? loc.file.path.string ()
+                        : loc.file.name ? *loc.file.name : string ());
+
+      const string psig ("# c++ " + to_string (version));
+      const string lsig ("// " + lf + ':' + to_string (loc.line));
+
+      // Check whether we need to (re)create the project.
+      //
+      optional<bool> altn (false); // Standard naming scheme.
+      bool create (!is_src_root (pd, altn));
+
+      if (!create && (create = !check_sig (bf, psig)))
+        rmdir_r (ctx, pd, false, verbosity); // Never dry-run.
+
+      path of;
+      ofdstream ofs;
+
+      if (create)
+      try
+      {
+        const fragments& frag (split ());
+
+        // Write ad hoc config.build that loads the ~build2 configuration.
+        // This way the configuration will be always in sync with ~build2
+        // and we can update the recipe manually (e.g., for debugging).
+        //
+        create_project (
+          pd,
+          dir_path (),                             /* amalgamation */
+          {},                                      /* boot_modules */
+          "cxx.std = latest",                      /* root_pre */
+          {"cxx."},                                /* root_modules */
+          "",                                      /* root_post */
+          string ("config"),                       /* config_module */
+          string ("config.config.load = ~build2"), /* config_file */
+          false,                                   /* buildfile */
+          "build2 core",                           /* who */
+          verbosity);                              /* verbosity */
+
+
+        // Write the rule source file.
+        //
+        of = path (pd / "rule.cxx");
+
+        if (verb >= verbosity)
+          text << (verb >= 2 ? "cat >" : "save ") << of;
+
+        ofs.open (of);
+
+        ofs << "#include \"location.hxx\""                              << '\n'
+            << '\n';
+
+        // Include every header that can plausibly be needed by a rule.
+        //
+        // @@ TMP: any new headers to add? [Keep this note for review.]
+        //
+        ofs << "#include <libbuild2/types.hxx>"                         << '\n'
+            << "#include <libbuild2/forward.hxx>"                       << '\n'
+            << "#include <libbuild2/utility.hxx>"                       << '\n'
+            << '\n'
+            << "#include <libbuild2/file.hxx>"                          << '\n'
+            << "#include <libbuild2/rule.hxx>"                          << '\n'
+            << "#include <libbuild2/depdb.hxx>"                         << '\n'
+            << "#include <libbuild2/scope.hxx>"                         << '\n'
+            << "#include <libbuild2/target.hxx>"                        << '\n'
+            << "#include <libbuild2/context.hxx>"                       << '\n'
+            << "#include <libbuild2/variable.hxx>"                      << '\n'
+            << "#include <libbuild2/algorithm.hxx>"                     << '\n'
+            << "#include <libbuild2/filesystem.hxx>"                    << '\n'
+            << "#include <libbuild2/diagnostics.hxx>"                   << '\n'
+            << "#include <libbuild2/adhoc-rule-cxx.hxx>"                << '\n'
+            << '\n';
+
+        // Write the global fragment, if any. Note that it always includes the
+        // trailing newline.
+        //
+        if (frag.global_n != 0)
+        {
+          // 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
+          // line and a file). Let's not bother for now.
+          //
+          ofs << "#line RECIPE_GLOBAL_LINE RECIPE_FILE"                 << '\n';
+          ofs.write (code.c_str () + frag.global_p, frag.global_n);
+          ofs << '\n';
+        }
+
+        // Normally the recipe code will have one level of indentation so
+        // let's not indent the namespace level to match.
+        //
+        ofs << "namespace build2"                                       << '\n'
+            << "{"                                                      << '\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 unnamed 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_v1"                         << '\n'
+            << "{"                                                      << '\n'
+            << "public:"                                                << '\n'
+            << '\n';
+
+        // Inherit base constructor. This way the user may provide their own
+        // but don't have to.
+        //
+        ofs << "  using cxx_rule_v1::cxx_rule_v1;"                      << '\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_v1*"                                  << '\n'
+            << "  create_" << id << " (const location& l, target_state s)" << '\n'
+            << "  {"                                                    << '\n'
+            << "    return new rule (l, s);"                            << '\n'
+            << "  }"                                                    << '\n'
+            << '\n';
+
+        // Use the #line directive to point diagnostics to the code in the
+        // buildfile similar to the global fragment above.
+        //
+        ofs << "#line RECIPE_LOCAL_LINE RECIPE_FILE"                    << '\n';
+
+        // Note that the local fragment always includes the trailing newline.
+        //
+        ofs.write (code.c_str () + frag.local_p, frag.local_n);
+        ofs << "};"                                                     << '\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'
+            << "cxx_rule_v1* (*" << sym << " ()) (const location&, target_state)" << '\n'
+            << "{"                                                      << '\n'
+            << "  return &rule_" << id << "::create_" << id << ";"      << '\n'
+            << "}"                                                      << '\n'
+            << '\n';
+
+        ofs << "}"                                                      << '\n';
+
+        ofs.close ();
+
+
+        // Write buildfile.
+        //
+        of = bf;
+
+        if (verb >= verbosity)
+          text << (verb >= 2 ? "cat >" : "save ") << of;
+
+        ofs.open (of);
+
+        ofs << "import imp_libs += build2%lib{build2}"                  << '\n'
+            << "libs{" << id << "}: cxx{rule} hxx{location} $imp_libs"  << '\n'
+            << '\n'
+            << "if ($cxx.target.system == 'win32-msvc')"                << '\n'
+            << "  cxx.poptions += -D_CRT_SECURE_NO_WARNINGS -D_SCL_SECURE_NO_WARNINGS" << '\n'
+            << '\n'
+            << "if ($cxx.class == 'msvc')"                              << '\n'
+            << "  cxx.coptions += /wd4251 /wd4275 /wd4800"              << '\n'
+            << '\n'
+            << psig                                                     << '\n';
+
+        ofs.close ();
+      }
+      catch (const io_error& e)
+      {
+        fail << "unable to write to " << of << ": " << e;
+      }
+
+      // Update the library target in the module context.
+      //
+      const target* l (nullptr);
+      do // Breakout loop.
+      {
+        // Load the project in the module context.
+        //
+        // Note that it's possible it has already been loaded (see above about
+        // the id calculation).
+        //
+        scope& rs (load_project (ctx, pd, pd, false /* forwarded */));
+
+        auto find_target = [&ctx, &rs, &pd, &id] ()
+        {
+          const target_type* tt (rs.find_target_type ("libs"));
+          assert (tt != nullptr);
+
+          const target* t (
+            ctx.targets.find (*tt, pd, dir_path () /* out */, id));
+          assert (t != nullptr);
+
+          return t;
+        };
+
+        // If the project has already been loaded then, as an optimization,
+        // check if the target has already been updated (this will make a
+        // difference we if we have identical recipes in several buildfiles,
+        // especially to the location update that comes next).
+        //
+        if (!source_once (rs, rs, bf))
+        {
+          l = find_target ();
+
+          if (l->executed_state (perform_update_id) != target_state::unknown)
+            break;
+        }
+
+        // Create/update the recipe location header.
+        //
+        // For update, preserve the file timestamp in order not to render the
+        // recipe out of date.
+        //
+        of = path (pd / "location.hxx");
+        if (!check_sig (of, lsig))
+        try
+        {
+          const fragments& frag (split ());
+
+          entry_time et (file_time (of));
+
+          if (verb >= verbosity)
+            text << (verb >= 2 ? "cat >" : "save ") << of;
+
+          ofs.open (of);
+
+          // Recipe file and line for the #line directive above. We also need
+          // to escape backslashes (Windows paths).
+          //
+          ofs << "#define RECIPE_FILE \"" << sanitize_strlit (lf) << '"'<< '\n';
+
+          if (frag.global_n != 0)
+            ofs << "#define RECIPE_GLOBAL_LINE " << frag.global_l.line  << '\n';
+
+          ofs << "#define RECIPE_LOCAL_LINE " << frag.local_l.line      << '\n'
+              << '\n'
+              << lsig                                                   << '\n';
+
+          ofs.close ();
+
+          if (et.modification != timestamp_nonexistent)
+            file_time (of, et);
+        }
+        catch (const io_error& e)
+        {
+          fail << "unable to write to " << of << ": " << e;
+        }
+        catch (const system_error& e)
+        {
+          fail << "unable to get/set timestamp for " << of << ": " << e;
+        }
+
+        if (nested)
+        {
+          // This means there is a perform update action already in progress
+          // in this context. So we are going to switch the phase and
+          // perform direct match and update (similar how we do this for
+          // generated headers).
+          //
+          // Note that since neither match nor execute are serial phases, it
+          // means other targets in this context can be matched and executed
+          // in paralellel with us.
+          //
+          if (l == nullptr)
+            l = find_target ();
+
+          phase_switch mp (ctx, run_phase::match);
+          if (build2::match (perform_update_id, *l) != target_state::unchanged)
+          {
+            phase_switch ep (ctx, run_phase::execute);
+            execute (a, *l);
+          }
+        }
+        else
+        {
+          // Cutoff the existing diagnostics stack and push our own entry.
+          //
+          diag_frame::stack_guard diag_cutoff (nullptr);
+
+          auto df = make_diag_frame (
+            [this, &t] (const diag_record& dr)
+            {
+              dr << info (loc) << "while updating ad hoc recipe for target "
+                 << t;
+            });
+
+          l = &update_in_module_context (
+            ctx, rs, names {name (pd, "libs", id)},
+            loc, bf);
+        }
+      } while (false);
+
+      // Load the library.
+      //
+      const path& lib (l->as<file> ().path ());
+
+      // Note again that it's possible the library has already been loaded
+      // (see above about the id calculation).
+      //
+      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;
+
+      if (hs.second == nullptr)
+        fail (loc) << "unable to lookup " << sym << " in recipe library "
+                   << lib << ": " << err;
+
+      {
+        auto df = make_diag_frame (
+          [this](const diag_record& dr)
+          {
+            if (verb != 0)
+              dr << info (loc) << "while initializing ad hoc recipe";
+          });
+
+        load_function* lf (function_cast<load_function*> (hs.second));
+        create_function* cf (lf ());
+
+        impl = cf (loc, l->executed_state (perform_update_id));
+        this->impl.store (impl, memory_order_relaxed); // Still in load phase.
+      }
+    }
+
+    return impl->match (a, t, hint);
+  }
+#endif // BUILD2_BOOTSTRAP || LIBBUILD2_STATIC_BUILD
+
+  recipe adhoc_cxx_rule::
+  apply (action a, target& t) const
+  {
+    return impl.load (memory_order_relaxed)->apply (a, t);
+  }
+}