Rework C/C++ standard translation in preparation for experimental/modules

Also fix bug in clang-apple versioning.

7 files changed, 45 insertions, 57 deletions

diff --git a/build2/cc/common.hxx b/build2/cc/common.hxx
index 55e6675..fa6ec5a 100644
--- a/build2/cc/common.hxx
+++ b/build2/cc/common.hxx
@@ -112,7 +112,7 @@ namespace build2
       const string& tsys;          // x.target.system
       const string& tclass;        // x.target.class
 
-      const string& tstd;          // Translated x_std value (can be empty).
+      const strings& tstd;         // Translated x_std value (options).
 
       const process_path* pkgconfig; // pkgconfig.path (can be NULL).
       const dir_paths& sys_lib_dirs; // x.sys_lib_dirs
@@ -153,7 +153,7 @@ namespace build2
             uint64_t mj, uint64_t mi,
             const process_path& path,
             const target_triplet& tg,
-            const string& std,
+            const strings& std,
             const process_path* pkgc,
             const dir_paths& sld,
             const dir_paths& sid,
@@ -177,22 +177,6 @@ namespace build2
     public:
       common (data&& d): data (move (d)) {}
 
-      // Language standard (x.std) mapping.
-      //
-      void
-      append_std (cstrings& args) const
-      {
-        if (!tstd.empty ())
-          args.push_back (tstd.c_str ());
-      }
-
-      void
-      hash_std (sha256& cs) const
-      {
-        if (!tstd.empty ())
-          cs.append (tstd);
-      }
-
       // Library handling.
       //
     public:
diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index 5a95169..ce96e00 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -531,7 +531,7 @@ namespace build2
 
         hash_options (cs, t, c_coptions);
         hash_options (cs, t, x_coptions);
-        hash_std (cs);
+        hash_options (cs, tstd);
 
         if (ct == otype::s)
         {
@@ -1183,8 +1183,7 @@ namespace build2
           //
           append_options (args, t, c_coptions);
           append_options (args, t, x_coptions);
-
-          append_std (args);
+          append_options (args, tstd);
 
           if (cid == compiler_id::msvc)
           {
@@ -2057,8 +2056,7 @@ namespace build2
           //
           append_options (args, t, c_coptions);
           append_options (args, t, x_coptions);
-
-          append_std (args);
+          append_options (args, tstd);
 
           if (cid == compiler_id::msvc)
           {
@@ -2272,11 +2270,10 @@ namespace build2
 
       append_options (args, t, c_coptions);
       append_options (args, t, x_coptions);
+      append_options (args, tstd);
 
       string out, out1; // Storage.
 
-      append_std (args);
-
       if (cid == compiler_id::msvc)
       {
         // The /F*: option variants with separate names only became available
diff --git a/build2/cc/gcc.cxx b/build2/cc/gcc.cxx
index b5dd236..7f52a91 100644
--- a/build2/cc/gcc.cxx
+++ b/build2/cc/gcc.cxx
@@ -38,7 +38,7 @@ namespace build2
       args.push_back (xc.recall_string ());
       append_options (args, rs, c_coptions);
       append_options (args, rs, x_coptions);
-      if (!tstd.empty ()) args.push_back (tstd.c_str ());
+      append_options (args, tstd);
       append_options (args, rs, c_loptions);
       append_options (args, rs, x_loptions);
       args.push_back ("-print-search-dirs");
diff --git a/build2/cc/guess.cxx b/build2/cc/guess.cxx
index 9f14661..7dde013 100644
--- a/build2/cc/guess.cxx
+++ b/build2/cc/guess.cxx
@@ -1096,28 +1096,33 @@ namespace build2
       compiler_info r;
       const compiler_id& id (gr.id);
 
-      if (id.type == "gcc")
+      switch (id.value ())
       {
-        assert (id.variant.empty ());
-        r = guess_gcc (xl, xc, c_coptions, x_coptions, move (gr));
-      }
-      else if (id.type == "clang")
-      {
-        assert (id.variant.empty () || id.variant == "apple");
-        r = guess_clang (xl, xc, c_coptions, x_coptions, move (gr));
-      }
-      else if (id.type == "icc")
-      {
-        assert (id.variant.empty ());
-        r = guess_icc (xl, xc, c_coptions, x_coptions, move (gr));
-      }
-      else if (id.type == "msvc")
-      {
-        assert (id.variant.empty ());
-        r = guess_msvc (xl, xc, c_coptions, x_coptions, move (gr));
+      case compiler_id::gcc:
+        {
+          assert (id.variant.empty ());
+          r = guess_gcc (xl, xc, c_coptions, x_coptions, move (gr));
+          break;
+        }
+      case compiler_id::clang:
+        {
+          assert (id.variant.empty () || id.variant == "apple");
+          r = guess_clang (xl, xc, c_coptions, x_coptions, move (gr));
+          break;
+        }
+      case compiler_id::msvc:
+        {
+          assert (id.variant.empty ());
+          r = guess_msvc (xl, xc, c_coptions, x_coptions, move (gr));
+          break;
+        }
+      case compiler_id::icc:
+        {
+          assert (id.variant.empty ());
+          r = guess_icc (xl, xc, c_coptions, x_coptions, move (gr));
+          break;
+        }
       }
-      else
-        assert (false);
 
       // Derive binutils pattern unless this has already been done by the
       // compiler-specific code.
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index 91c2739..5c75d34 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -1192,7 +1192,7 @@ namespace build2
         {
           append_options (args, t, c_coptions);
           append_options (args, t, x_coptions);
-          append_std (args);
+          append_options (args, tstd);
         }
 
         append_options (args, t, c_loptions);
diff --git a/build2/cc/module.cxx b/build2/cc/module.cxx
index 885d6c7..cdc45e5 100644
--- a/build2/cc/module.cxx
+++ b/build2/cc/module.cxx
@@ -118,10 +118,9 @@ namespace build2
         }
       }
 
-      // Translate x_std value (if any) to the compiler option (if any).
+      // Translate x_std value (if any) to the compiler option(s) (if any).
       //
-      if (auto l = rs[x_std])
-        tstd = translate_std (ci, rs, cast<string> (*l));
+      tstd = translate_std (ci, rs, cast_null<string> (rs[x_std]));
 
       // Extract system library search paths from the compiler and determine
       // additional system include search paths.
@@ -129,7 +128,7 @@ namespace build2
       dir_paths lib_dirs;
       dir_paths inc_dirs;
 
-      if (ci.id.type == "msvc")
+      if (ci.id.value () == compiler_id::msvc)
         lib_dirs = msvc_library_search_paths (ci.path, rs);
       else
       {
@@ -188,7 +187,9 @@ namespace build2
 
         if (!tstd.empty ())
         {
-          dr << "  std        " << tstd << '\n';
+          dr << "  std       "; // One less space.
+          for (const string& o: tstd) dr << ' ' << o;
+          dr << '\n';
         }
 
         if (!ci.cc_pattern.empty ()) // bin_pattern printed by bin
diff --git a/build2/cc/module.hxx b/build2/cc/module.hxx
index eaa82eb..db17998 100644
--- a/build2/cc/module.hxx
+++ b/build2/cc/module.hxx
@@ -32,13 +32,14 @@ namespace build2
       void
       init (scope&, const location&, const variable_map&);
 
-      // Translate the x.std value to the standard-selecting option if there
-      // is any.
+      // Translate the x.std value (if any) to the standard-selecting
+      // option(s) (if any). May also check/set x.features.* variables on the
+      // root scope.
       //
-      virtual string
-      translate_std (const compiler_info&, scope&, const string&) const = 0;
+      virtual strings
+      translate_std (const compiler_info&, scope&, const string*) const = 0;
 
-      string tstd;
+      strings tstd;
 
       compiler_id::value_type cid;