Add support for rule hints

A rule hint is a target attribute, for example:

[rule_hint=cxx] exe{hello}: c{hello}

Rule hints can be used to resolve ambiguity when multiple rules match the same
target as well as to override an unambiguous match.

9 files changed, 43 insertions, 45 deletions

diff --git a/libbuild2/cc/common.hxx b/libbuild2/cc/common.hxx
index 56cde19..017573d 100644
--- a/libbuild2/cc/common.hxx
+++ b/libbuild2/cc/common.hxx
@@ -156,10 +156,9 @@ namespace build2
 
     struct data: config_data
     {
-      const char* x_compile; // Rule names.
-      const char* x_link;
-      const char* x_install;
-      const char* x_uninstall;
+      string x_compile; // Rule names.
+      string x_link;
+      string x_install;
 
       // Cached values for some commonly-used variables/values.
       //
@@ -243,7 +242,6 @@ namespace build2
             const char* compile,
             const char* link,
             const char* install,
-            const char* uninstall,
             compiler_type ct,
             const string& cv,
             compiler_class cl,
@@ -270,7 +268,6 @@ namespace build2
             x_compile (compile),
             x_link (link),
             x_install (install),
-            x_uninstall (uninstall),
             ctype (ct), cvariant (cv), cclass (cl),
             cmaj (mj), cmin (mi),
             cvmaj (vmj), cvmin (vmi),
diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index e7e90ad..24c9b2b 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -406,7 +406,7 @@ namespace build2
     }
 
     bool compile_rule::
-    match (action a, target& t, const string&) const
+    match (action a, target& t) const
     {
       tracer trace (x, "compile_rule::match");
 
diff --git a/libbuild2/cc/compile-rule.hxx b/libbuild2/cc/compile-rule.hxx
index dbb2dd5..00965fc 100644
--- a/libbuild2/cc/compile-rule.hxx
+++ b/libbuild2/cc/compile-rule.hxx
@@ -45,7 +45,7 @@ namespace build2
       compile_rule (data&&);
 
       virtual bool
-      match (action, target&, const string&) const override;
+      match (action, target&) const override;
 
       virtual recipe
       apply (action, target&) const override;
diff --git a/libbuild2/cc/install-rule.cxx b/libbuild2/cc/install-rule.cxx
index 560b8a7..e8c87ae 100644
--- a/libbuild2/cc/install-rule.cxx
+++ b/libbuild2/cc/install-rule.cxx
@@ -97,7 +97,7 @@ namespace build2
       {
         if (header_source (p))
           pt = nullptr;
-        else if (p.type.see_through)
+        else if (p.type.see_through ())
         {
           for (i.enter_group (); i.group (); )
           {
@@ -151,15 +151,13 @@ namespace build2
     }
 
     bool install_rule::
-    match (action a, target& t, const string& hint) const
+    match (action a, target& t, const string&, match_extra& me) const
     {
-      // @@ How do we split the hint between the two?
-      //
-
       // We only want to handle installation if we are also the ones building
       // this target. So first run link's match().
       //
-      return link_.match (a, t, hint) && file_rule::match (a, t, "");
+      return link_.sub_match (x_link, update_id, a, t, me) &&
+        file_rule::match (a, t);
     }
 
     recipe install_rule::
@@ -332,7 +330,7 @@ namespace build2
       {
         if (header_source (p))
           pt = nullptr;
-        else if (p.type.see_through)
+        else if (p.type.see_through ())
         {
           for (i.enter_group (); i.group (); )
           {
@@ -372,12 +370,13 @@ namespace build2
     }
 
     bool libux_install_rule::
-    match (action a, target& t, const string& hint) const
+    match (action a, target& t, const string&, match_extra& me) const
     {
       // We only want to handle installation if we are also the ones building
       // this target. So first run link's match().
       //
-      return link_.match (a, t, hint) && alias_rule::match (a, t, "");
+      return link_.sub_match (x_link, update_id, a, t, me) &&
+        alias_rule::match (a, t);
     }
   }
 }
diff --git a/libbuild2/cc/install-rule.hxx b/libbuild2/cc/install-rule.hxx
index acd1bd8..70ee711 100644
--- a/libbuild2/cc/install-rule.hxx
+++ b/libbuild2/cc/install-rule.hxx
@@ -38,8 +38,10 @@ namespace build2
       filter (const scope*,
               action, const target&, prerequisite_iterator&) const override;
 
+      // Note: rule::match() override.
+      //
       virtual bool
-      match (action, target&, const string&) const override;
+      match (action, target&, const string&, match_extra&) const override;
 
       virtual recipe
       apply (action, target&) const override;
@@ -71,8 +73,10 @@ namespace build2
       filter (const scope*,
               action, const target&, prerequisite_iterator&) const override;
 
+      // Note: rule::match() override.
+      //
       virtual bool
-      match (action, target&, const string&) const override;
+      match (action, target&, const string&, match_extra&) const override;
 
     private:
       const link_rule& link_;
diff --git a/libbuild2/cc/link-rule.cxx b/libbuild2/cc/link-rule.cxx
index b5cc63b..30024ce 100644
--- a/libbuild2/cc/link-rule.cxx
+++ b/libbuild2/cc/link-rule.cxx
@@ -446,7 +446,7 @@ namespace build2
     }
 
     bool link_rule::
-    match (action a, target& t, const string& hint) const
+    match (action a, target& t, const string& hint, match_extra&) const
     {
       // NOTE: may be called multiple times and for both inner and outer
       //       operations (see the install rules).
@@ -495,7 +495,7 @@ namespace build2
       // We will only chain a C source if there is also an X source or we were
       // explicitly told to.
       //
-      if (r.seen_c && !r.seen_x && hint < x)
+      if (r.seen_c && !r.seen_x && hint.empty ())
       {
         l4 ([&]{trace << "C prerequisite without " << x_lang << " or hint "
                       << "for target " << t;});
@@ -850,7 +850,7 @@ namespace build2
     };
 
     recipe link_rule::
-    apply (action a, target& xt) const
+    apply (action a, target& xt, match_extra&) const
     {
       tracer trace (x, "link_rule::apply");
 
diff --git a/libbuild2/cc/link-rule.hxx b/libbuild2/cc/link-rule.hxx
index c6d06d2..f0052e9 100644
--- a/libbuild2/cc/link-rule.hxx
+++ b/libbuild2/cc/link-rule.hxx
@@ -18,7 +18,7 @@ namespace build2
 {
   namespace cc
   {
-    class LIBBUILD2_CC_SYMEXPORT link_rule: public simple_rule, virtual common
+    class LIBBUILD2_CC_SYMEXPORT link_rule: public rule, virtual common
     {
     public:
       link_rule (data&&);
@@ -46,10 +46,10 @@ namespace build2
       match (action, const target&, const target*, otype, bool) const;
 
       virtual bool
-      match (action, target&, const string&) const override;
+      match (action, target&, const string&, match_extra&) const override;
 
       virtual recipe
-      apply (action, target&) const override;
+      apply (action, target&, match_extra&) const override;
 
       target_state
       perform_update (action, const target&) const;
@@ -57,8 +57,6 @@ namespace build2
       target_state
       perform_clean (action, const target&) const;
 
-      using simple_rule::match; // To make Clang happy.
-
     public:
       // Library handling.
       //
diff --git a/libbuild2/cc/module.cxx b/libbuild2/cc/module.cxx
index 871cfb6..c930d49 100644
--- a/libbuild2/cc/module.cxx
+++ b/libbuild2/cc/module.cxx
@@ -1083,30 +1083,30 @@ namespace build2
         {
           const install_rule&  ir (*this);
 
-          r.insert<exe>  (perform_install_id,   x_install,   ir);
-          r.insert<exe>  (perform_uninstall_id, x_uninstall, ir);
+          r.insert<exe>  (perform_install_id,   x_install, ir);
+          r.insert<exe>  (perform_uninstall_id, x_install, ir);
 
-          r.insert<liba> (perform_install_id,   x_install,   ir);
-          r.insert<liba> (perform_uninstall_id, x_uninstall, ir);
+          r.insert<liba> (perform_install_id,   x_install, ir);
+          r.insert<liba> (perform_uninstall_id, x_install, ir);
 
           if (s)
           {
-            r.insert<libs> (perform_install_id,   x_install,   ir);
-            r.insert<libs> (perform_uninstall_id, x_uninstall, ir);
+            r.insert<libs> (perform_install_id,   x_install, ir);
+            r.insert<libs> (perform_uninstall_id, x_install, ir);
           }
 
           const libux_install_rule& lr (*this);
 
-          r.insert<libue> (perform_install_id,   x_install,   lr);
-          r.insert<libue> (perform_uninstall_id, x_uninstall, lr);
+          r.insert<libue> (perform_install_id,   x_install, lr);
+          r.insert<libue> (perform_uninstall_id, x_install, lr);
 
-          r.insert<libua> (perform_install_id,   x_install,   lr);
-          r.insert<libua> (perform_uninstall_id, x_uninstall, lr);
+          r.insert<libua> (perform_install_id,   x_install, lr);
+          r.insert<libua> (perform_uninstall_id, x_install, lr);
 
           if (s)
           {
-            r.insert<libus> (perform_install_id,   x_install,   lr);
-            r.insert<libus> (perform_uninstall_id, x_uninstall, lr);
+            r.insert<libus> (perform_install_id,   x_install, lr);
+            r.insert<libus> (perform_uninstall_id, x_install, lr);
           }
         }
       }
diff --git a/libbuild2/cc/target.cxx b/libbuild2/cc/target.cxx
index b17e1ef..3f71eb1 100644
--- a/libbuild2/cc/target.cxx
+++ b/libbuild2/cc/target.cxx
@@ -21,7 +21,7 @@ namespace build2
       nullptr,
       nullptr,
       &target_search,
-      false
+      target_type::flag::none
     };
 
     extern const char h_ext_def[] = "h";
@@ -36,7 +36,7 @@ namespace build2
       &target_pattern_var<h_ext_def>,
       nullptr,
       &file_search,
-      false
+      target_type::flag::none
     };
 
     extern const char c_ext_def[] = "c";
@@ -51,7 +51,7 @@ namespace build2
       &target_pattern_var<c_ext_def>,
       nullptr,
       &file_search,
-      false
+      target_type::flag::none
     };
 
     extern const char pc_ext[] = "pc"; // VC14 rejects constexpr.
@@ -66,7 +66,7 @@ namespace build2
       &target_pattern_fix<pc_ext>,
       &target_print_0_ext_verb, // Fixed extension, no use printing.
       &file_search,
-      false
+      target_type::flag::none
     };
 
     extern const char pca_ext[] = "static.pc"; // VC14 rejects constexpr.
@@ -81,7 +81,7 @@ namespace build2
       &target_pattern_fix<pca_ext>,
       &target_print_0_ext_verb, // Fixed extension, no use printing.
       &file_search,
-      false
+      target_type::flag::none
     };
 
     extern const char pcs_ext[] = "shared.pc"; // VC14 rejects constexpr.
@@ -96,7 +96,7 @@ namespace build2
       &target_pattern_fix<pcs_ext>,
       &target_print_0_ext_verb, // Fixed extension, no use printing.
       &file_search,
-      false
+      target_type::flag::none
     };
   }
 }