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.

1 files changed, 4 insertions, 3 deletions

diff --git a/libbuild2/bash/rule.hxx b/libbuild2/bash/rule.hxx
index f69ac3b..1a0cb36 100644
--- a/libbuild2/bash/rule.hxx
+++ b/libbuild2/bash/rule.hxx
@@ -32,7 +32,7 @@ namespace build2
       in_rule (): rule ("bash.in 1", "bash.in", '@', false /* strict */) {}
 
       virtual bool
-      match (action, target&, const string&) const override;
+      match (action, target&) const override;
 
       virtual recipe
       apply (action, target&) const override;
@@ -68,16 +68,17 @@ namespace build2
     class LIBBUILD2_BASH_SYMEXPORT install_rule: public install::file_rule
     {
     public:
-      install_rule (const in_rule& in): in_ (in) {}
+      install_rule (const in_rule& r, const char* n): in_ (r), in_name_ (n) {}
 
       virtual bool
-      match (action, target&, const string&) const override;
+      match (action, target&) const override;
 
       virtual recipe
       apply (action, target&) const override;
 
     protected:
       const in_rule& in_;
+      const string in_name_;
     };
   }
 }