From db0edaafe15831ba6fa9c2109da37942506c62b1 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sat, 23 Jan 2016 11:14:05 +0200
Subject: Cleanup absolute/relative path diagnostics by introducing stream
 verbosity

---
 build2/b.cxx            |   7 ++-
 build2/context          |  49 +++++++++++++---
 build2/context.cxx      |  25 ++------
 build2/diagnostics      | 150 ++++++++++++++++++++++++------------------------
 build2/diagnostics.cxx  |  19 +++---
 build2/file.cxx         |   6 +-
 build2/lexer            |   8 +--
 build2/lexer.cxx        |   2 +-
 build2/parser           |   9 +--
 build2/parser.cxx       |  26 ++++-----
 build2/path-io.cxx      |   6 +-
 build2/prerequisite.cxx |  22 +++++--
 build2/spec.cxx         |  16 ++++--
 build2/target.cxx       |  12 +++-
 build2/types            |  13 ++++-
 15 files changed, 212 insertions(+), 158 deletions(-)

diff --git a/build2/b.cxx b/build2/b.cxx
index cc87cec..c6a118e 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -151,7 +151,7 @@ main (int argc, char* argv[])
 
       istringstream is (s);
       is.exceptions (istringstream::failbit | istringstream::badbit);
-      lexer l (is, "<cmdline>");
+      lexer l (is, path ("<cmdline>"));
       token t (l.next ());
 
       if (t.type == token_type::eos)
@@ -202,7 +202,7 @@ main (int argc, char* argv[])
         is.exceptions (istringstream::failbit | istringstream::badbit);
 
         parser p;
-        bspec = p.parse_buildspec (is, "<buildspec>");
+        bspec = p.parse_buildspec (is, path ("<buildspec>"));
       }
       catch (const istringstream::failure&)
       {
@@ -227,7 +227,8 @@ main (int argc, char* argv[])
 
       for (opspec& os: ms)
       {
-        const location l ("<buildspec>", 1, 0); //@@ TODO
+        const path p ("<buildspec>");
+        const location l (&p, 1, 0); //@@ TODO
 
         if (os.empty ()) // Default target: dir{}.
           os.push_back (targetspec (name ("dir", string ())));
diff --git a/build2/context b/build2/context
index 7bae8c3..e2732db 100644
--- a/build2/context
+++ b/build2/context
@@ -23,7 +23,6 @@ namespace build2
   extern dir_path work;
   extern dir_path home;
 
-  extern string_pool path_pool;
   extern string_pool extension_pool;
   extern string_pool project_name_pool;
 
@@ -146,18 +145,52 @@ namespace build2
   diag_relative (const dir_path&, bool current = true);
 
   // Action phrases, e.g., "configure update exe{foo}", "updating exe{foo}",
-  // and "updating exe{foo} is configured".
+  // and "updating exe{foo} is configured". Use like this:
+  //
+  // info << "while " << diag_doing (a, t);
   //
   class target;
 
-  std::string
-  diag_do (const action&, const target&);
+  struct diag_phrase
+  {
+    const action& a;
+    const target& t;
+    void (*f) (ostream&, const action&, const target&);
+  };
 
-  std::string
-  diag_doing (const action&, const target&);
+  inline ostream&
+  operator<< (ostream& os, const diag_phrase& p)
+  {
+    p.f (os, p.a, p.t);
+    return os;
+  }
 
-  std::string
-  diag_done (const action&, const target&);
+  void
+  diag_do (ostream&, const action&, const target&);
+
+  inline diag_phrase
+  diag_do (const action& a, const target& t)
+  {
+    return diag_phrase {a, t, &diag_do};
+  }
+
+  void
+  diag_doing (ostream&, const action&, const target&);
+
+  inline diag_phrase
+  diag_doing (const action& a, const target& t)
+  {
+    return diag_phrase {a, t, &diag_doing};
+  }
+
+  void
+  diag_done (ostream&, const action&, const target&);
+
+  inline diag_phrase
+  diag_done (const action& a, const target& t)
+  {
+    return diag_phrase {a, t, &diag_done};
+  }
 }
 
 #include <build2/context.txx>
diff --git a/build2/context.cxx b/build2/context.cxx
index 0579545..87a6d71 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -5,7 +5,6 @@
 #include <build2/context>
 
 #include <ostream>
-#include <sstream>
 #include <cassert>
 #include <system_error>
 
@@ -22,7 +21,6 @@ namespace build2
   dir_path work;
   dir_path home;
 
-  string_pool path_pool;
   string_pool extension_pool;
   string_pool project_name_pool;
 
@@ -35,7 +33,6 @@ namespace build2
   void
   reset ()
   {
-    path_pool.clear ();
     extension_pool.clear ();
     project_name_pool.clear ();
 
@@ -299,15 +296,13 @@ namespace build2
 
   // diag_do(), etc.
   //
-  string
-  diag_do (const action&, const target& t)
+  void
+  diag_do (ostream& os, const action&, const target& t)
   {
     const meta_operation_info& m (*current_mif);
     const operation_info& io (*current_inner_oif);
     const operation_info* oo (current_outer_oif);
 
-    ostringstream os;
-
     // perform(update(x))   -> "update x"
     // configure(update(x)) -> "configure updating x"
     //
@@ -325,18 +320,15 @@ namespace build2
       os << "(for " << oo->name << ") ";
 
     os << t;
-    return os.str ();
   }
 
-  string
-  diag_doing (const action&, const target& t)
+  void
+  diag_doing (ostream& os, const action&, const target& t)
   {
     const meta_operation_info& m (*current_mif);
     const operation_info& io (*current_inner_oif);
     const operation_info* oo (current_outer_oif);
 
-    ostringstream os;
-
     // perform(update(x))   -> "updating x"
     // configure(update(x)) -> "configuring updating x"
     //
@@ -350,18 +342,15 @@ namespace build2
       os << "(for " << oo->name << ") ";
 
     os << t;
-    return os.str ();
   }
 
-  string
-  diag_done (const action&, const target& t)
+  void
+  diag_done (ostream& os, const action&, const target& t)
   {
     const meta_operation_info& m (*current_mif);
     const operation_info& io (*current_inner_oif);
     const operation_info* oo (current_outer_oif);
 
-    ostringstream os;
-
     // perform(update(x))   -> "x is up to date"
     // configure(update(x)) -> "updating x is configured"
     //
@@ -385,7 +374,5 @@ namespace build2
 
       os << t << " " << m.name_done;
     }
-
-    return os.str ();
   }
 }
diff --git a/build2/diagnostics b/build2/diagnostics
index 4aef6dd..27c71fa 100644
--- a/build2/diagnostics
+++ b/build2/diagnostics
@@ -28,17 +28,6 @@ namespace build2
   //
   class failed: public std::exception {};
 
-  // Flag that indicates whether paths should be inserted relative
-  // into this stream.
-  //
-  extern const int relative_index;
-
-  inline bool
-  relative (std::ostream& os) {return os.iword (relative_index);}
-
-  inline void
-  relative (std::ostream& os, bool v) {os.iword (relative_index) = v ? 1 : 0;}
-
   // Print process commmand line. If the number of elements is specified
   // (or the second version is used), then it will print the piped multi-
   // process command line, if present. In this case, the expected format
@@ -67,7 +56,7 @@ namespace build2
     print_process (args.data (), args.size ());
   }
 
-  // Verbosity level.
+  // Program verbosity level (-v/--verbose).
   //
   // 0 - disabled
   // 1 - high-level information messages
@@ -79,7 +68,7 @@ namespace build2
   //
   // While uint8 is more than enough, use uint16 for the ease of printing.
   //
-  extern std::uint16_t verb;
+  extern uint16_t verb;
 
   template <typename F> inline void level1 (const F& f) {if (verb >= 1) f ();}
   template <typename F> inline void level2 (const F& f) {if (verb >= 2) f ();}
@@ -88,6 +77,46 @@ namespace build2
   template <typename F> inline void level5 (const F& f) {if (verb >= 5) f ();}
   template <typename F> inline void level6 (const F& f) {if (verb >= 6) f ();}
 
+  // Stream verbosity level. It is determined by the diagnostic type (e.g.,
+  // trace always has maximum verbosity) as well as the program verbosity. It
+  // is used to decide whether to print relative/absolute paths, and default
+  // target extensions.
+  //
+  // 0 - minimum
+  // 1 - intermediate
+  // 2 - maximum
+  //
+  // Currently we have the following program to stream verbosity mapping:
+  //
+  // fail/error/warn/info   <2:0  2:1 >2:2
+  // trace                  *:2
+  //
+  // A stream that hasn't been (yet) assigned any verbosity explicitly (e.g.,
+  // ostringstream) defaults to maximum.
+  //
+  const uint16_t stream_verb_min = 0;
+  const uint16_t stream_verb_max = 2;
+
+  // Default program to stream verbosity mapping, as outlined above.
+  //
+  inline uint16_t
+  stream_verb_map () {return verb < 2 ? 0 : (verb > 2 ? 2 : 1);}
+
+  extern const int stream_verb_index;
+
+  inline uint16_t
+  stream_verb (std::ostream& os)
+  {
+    uint16_t v (static_cast<uint16_t> (os.iword (stream_verb_index)));
+    return v == 0 ? stream_verb_max : v - 1;
+  }
+
+  inline void
+  stream_verb (std::ostream& os, uint16_t v)
+  {
+    os.iword (stream_verb_index) = static_cast<long> (v + 1);
+  }
+
   // Diagnostic facility, base infrastructure (potentially reusable).
   //
   extern std::ostream* diag_stream;
@@ -159,7 +188,7 @@ namespace build2
 
       if (!empty_)
       {
-        assert (false); //@@ Relative flag will not be transferred.
+        assert (false); //@@ Stream verbosity will not be transferred.
         os_ << r.os_.str ();
 
         r.empty_ = true;
@@ -243,8 +272,8 @@ namespace build2
   struct simple_prologue_base
   {
     explicit
-    simple_prologue_base (const char* type, const char* name, bool rel)
-        : type_ (type), name_ (name), relative_ (rel) {}
+    simple_prologue_base (const char* type, const char* name, uint16_t sverb)
+        : type_ (type), name_ (name), sverb_ (sverb) {}
 
     void
     operator() (const diag_record& r) const;
@@ -252,18 +281,20 @@ namespace build2
   private:
     const char* type_;
     const char* name_;
-    const bool relative_;
+    const uint16_t sverb_;
   };
   typedef diag_prologue<simple_prologue_base> simple_prologue;
 
   class location
   {
   public:
-    location () {}
-    location (const char* f, std::uint64_t l, std::uint64_t c)
+    // Note that location maintains a shallow reference to path.
+    //
+    location (): file (nullptr), line (0), column (0) {}
+    location (const path* f, std::uint64_t l, std::uint64_t c)
         : file (f), line (l), column (c) {}
 
-    const char* file;
+    const path* file;
     std::uint64_t line;
     std::uint64_t column;
   };
@@ -273,8 +304,8 @@ namespace build2
     location_prologue_base (const char* type,
                             const char* name,
                             const location& l,
-                            bool rel)
-        : type_ (type), name_ (name), loc_ (l), relative_ (rel) {}
+                            uint16_t sverb)
+        : type_ (type), name_ (name), loc_ (l), sverb_ (sverb) {}
 
     void
     operator() (const diag_record& r) const;
@@ -283,68 +314,55 @@ namespace build2
     const char* type_;
     const char* name_;
     const location loc_;
-    const bool relative_;
+    const uint16_t sverb_;
   };
   typedef diag_prologue<location_prologue_base> location_prologue;
 
-  // Here is the absolute/relative path rationale: we want it absolute
-  // in the error/warning/info streams to give the user the complete
-  // picture. But in the text stream (e.g., command lines), we print
-  // relative unless verbosity is greater than 1.
-  //
   struct basic_mark_base
   {
     explicit
-    basic_mark_base (const char* type,
+    basic_mark_base (uint16_t (*sverb) (),
+                     const char* type,
                      const char* name = nullptr,
-                     const void* data = nullptr)
-        : type_ (type), name_ (name), data_ (data) {}
+                     const void* data = nullptr,
+                     diag_epilogue epilogue = nullptr)
+        : sverb_ (sverb),
+          type_ (type), name_ (name), data_ (data),
+          epilogue_ (epilogue) {}
 
     simple_prologue
     operator() () const
     {
-      return simple_prologue (type_, name_, false);
+      return simple_prologue (epilogue_, type_, name_, sverb_ ());
     }
 
     location_prologue
     operator() (const location& l) const
     {
-      return location_prologue (type_, name_, l, false);
+      return location_prologue (epilogue_, type_, name_, l, sverb_ ());
     }
 
     template <typename L>
     location_prologue
     operator() (const L& l) const
     {
-      return location_prologue (type_, name_, get_location (l, data_), false);
+      return location_prologue (
+        epilogue_, type_, name_, get_location (l, data_), sverb_ ());
     }
 
   protected:
+    uint16_t (*sverb_) ();
     const char* type_;
     const char* name_;
     const void* data_;
+    const diag_epilogue epilogue_;
   };
   typedef diag_mark<basic_mark_base> basic_mark;
 
   extern const basic_mark error;
   extern const basic_mark warn;
   extern const basic_mark info;
-
-  // text
-  //
-  struct text_mark_base: basic_mark_base
-  {
-    text_mark_base (): basic_mark_base (nullptr) {}
-
-    simple_prologue
-    operator() () const
-    {
-      return simple_prologue (type_, name_, verb <= 1);
-    }
-  };
-  typedef diag_mark<text_mark_base> text_mark;
-
-  extern const text_mark text;
+  extern const basic_mark text;
 
   // trace
   //
@@ -352,7 +370,8 @@ namespace build2
   {
     explicit
     trace_mark_base (const char* name, const void* data = nullptr)
-        : basic_mark_base ("trace", name, data) {}
+        : basic_mark_base ([]() {return stream_verb_max;}, "trace", name, data)
+    {}
   };
   typedef diag_mark<trace_mark_base> trace_mark;
 
@@ -361,36 +380,15 @@ namespace build2
   // fail
   //
   template <typename E>
-  struct fail_mark_base
+  struct fail_mark_base: basic_mark_base
   {
     explicit
-    fail_mark_base (const void* data = nullptr): data_ (data) {}
-
-    simple_prologue
-    operator() () const
-    {
-      return simple_prologue (&epilogue, "error", nullptr, false);
-    }
-
-    location_prologue
-    operator() (const location& l) const
-    {
-      return location_prologue (&epilogue, "error", nullptr, l, false);
-    }
-
-    template <typename L>
-    location_prologue
-    operator() (const L& l) const
-    {
-      return location_prologue (
-        &epilogue, "error", nullptr, get_location (l, data_), false);
-    }
+    fail_mark_base (const void* data = nullptr)
+        : basic_mark_base (&stream_verb_map, "error", nullptr, data, &epilogue)
+    {}
 
     static void
     epilogue (const diag_record&) {throw E ();}
-
-  private:
-    const void* data_;
   };
 
   template <typename E>
diff --git a/build2/diagnostics.cxx b/build2/diagnostics.cxx
index 50e4578..fb108dc 100644
--- a/build2/diagnostics.cxx
+++ b/build2/diagnostics.cxx
@@ -13,9 +13,9 @@ using namespace std;
 
 namespace build2
 {
-  // Relative stream.
+  // Stream verbosity.
   //
-  const int relative_index = ostream::xalloc ();
+  const int stream_verb_index = ostream::xalloc ();
 
   void
   print_process (const char* const* args, size_t n)
@@ -94,7 +94,7 @@ namespace build2
   void simple_prologue_base::
   operator() (const diag_record& r) const
   {
-    relative (r.os_, relative_);
+    stream_verb (r.os_, sverb_);
 
     if (type_ != nullptr)
       r << type_ << ": ";
@@ -106,9 +106,9 @@ namespace build2
   void location_prologue_base::
   operator() (const diag_record& r) const
   {
-    relative (r.os_, relative_);
+    stream_verb (r.os_, sverb_);
 
-    r << loc_.file << ':' << loc_.line << ':' << loc_.column << ": ";
+    r << *loc_.file << ':' << loc_.line << ':' << loc_.column << ": ";
 
     if (type_ != nullptr)
       r << type_ << ": ";
@@ -117,9 +117,10 @@ namespace build2
       r << name_ << ": ";
   }
 
-  const basic_mark error ("error");
-  const basic_mark warn ("warning");
-  const basic_mark info ("info");
-  const text_mark text;
+  const basic_mark error (&stream_verb_map, "error");
+  const basic_mark warn  (&stream_verb_map, "warning");
+  const basic_mark info  (&stream_verb_map, "info");
+  const basic_mark text  (&stream_verb_map, nullptr);
+
   const fail_mark<failed> fail;
 }
diff --git a/build2/file.cxx b/build2/file.cxx
index 68b655e..9a5ab80 100644
--- a/build2/file.cxx
+++ b/build2/file.cxx
@@ -275,9 +275,7 @@ namespace build2
 
       ifs.exceptions (ifstream::failbit | ifstream::badbit);
 
-      path rbf (diag_relative (bf));
-
-      lexer lex (ifs, rbf.string ());
+      lexer lex (ifs, bf);
       token t (lex.next ());
       token_type tt;
 
@@ -286,7 +284,7 @@ namespace build2
            tt != token_type::prepend &&
            tt != token_type::append))
       {
-        error << "variable '" << var << "' expected as first line in " << rbf;
+        error << "variable '" << var << "' expected as first line in " << bf;
         throw failed (); // Suppress "used uninitialized" warning.
       }
 
diff --git a/build2/lexer b/build2/lexer
index 69ca0a8..06f2b24 100644
--- a/build2/lexer
+++ b/build2/lexer
@@ -44,14 +44,14 @@ namespace build2
   {
   public:
     lexer (std::istream& is,
-           const std::string& name,
+           const path& name,
            void (*processor) (token&, const lexer&) = nullptr)
         : char_scanner (is), fail (name), processor_ (processor), sep_ (false)
     {
       mode_.push (lexer_mode::normal);
     }
 
-    const std::string&
+    const path&
     name () const {return fail.name_;}
 
     // Note: sets mode for the next token. If mode is pairs, then
@@ -115,12 +115,12 @@ namespace build2
   private:
     struct fail_mark_base: build2::fail_mark_base<failed>
     {
-      fail_mark_base (const std::string& n): name_ (n) {}
+      fail_mark_base (const path& n): name_ (n) {}
 
       location_prologue
       operator() (const xchar&) const;
 
-      std::string name_;
+      path name_;
     };
     typedef diag_mark<fail_mark_base> fail_mark;
 
diff --git a/build2/lexer.cxx b/build2/lexer.cxx
index da3d64e..c73017e 100644
--- a/build2/lexer.cxx
+++ b/build2/lexer.cxx
@@ -458,6 +458,6 @@ namespace build2
   operator() (const xchar& c) const
   {
     return build2::fail_mark_base<failed>::operator() (
-      location (name_.c_str (), c.line, c.column));
+      location (&name_, c.line, c.column));
   }
 }
diff --git a/build2/parser b/build2/parser
index a379bd7..ae3add9 100644
--- a/build2/parser
+++ b/build2/parser
@@ -36,13 +36,14 @@ namespace build2
     // Issue diagnostics and throw failed in case of an error.
     //
     void
-    parse_buildfile (std::istream&, const path&, scope& root, scope& base);
+    parse_buildfile (std::istream&, const path& name,
+                     scope& root, scope& base);
 
     buildspec
-    parse_buildspec (std::istream&, const std::string& name);
+    parse_buildspec (std::istream&, const path& name);
 
     token
-    parse_variable (lexer&, scope&, std::string name, token_type kind);
+    parse_variable (lexer&, scope&, std::string var_name, token_type kind);
 
     names_type
     parse_export_stub (std::istream& is, const path& p, scope& r, scope& b)
@@ -285,7 +286,7 @@ namespace build2
   protected:
     bool boot_;
 
-    const std::string* path_; // Path processed by diag_relative() and pooled.
+    const path* path_; // Current path.
     lexer* lexer_;
     target* target_; // Current target, if any.
     scope* scope_;   // Current base scope (out_base).
diff --git a/build2/parser.cxx b/build2/parser.cxx
index 187c47e..7e07834 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -39,7 +39,7 @@ namespace build2
   {
     enter_buildfile (p);
 
-    path_ = &path_pool.find (diag_relative (p)); // Relative to work.
+    path_ = &p;
 
     lexer l (is, *path_);
     lexer_ = &l;
@@ -63,14 +63,14 @@ namespace build2
   token parser::
   parse_variable (lexer& l, scope& s, string name, type kind)
   {
-    path_ = &l.name (); // Note: not pooled.
+    path_ = &l.name ();
     lexer_ = &l;
     target_ = nullptr;
     scope_ = &s;
 
     type tt;
     token t (type::eos, false, 0, 0);
-    variable (t, tt, name, kind);
+    variable (t, tt, move (name), kind);
     return t;
   }
 
@@ -539,8 +539,8 @@ namespace build2
 
         enter_buildfile (p);
 
-        const string* op (path_);
-        path_ = &path_pool.find (diag_relative (p)); // Relative to work.
+        const path* op (path_);
+        path_ = &p;
 
         lexer l (ifs, *path_);
         lexer* ol (lexer_);
@@ -675,8 +675,8 @@ namespace build2
 
         enter_buildfile (p);
 
-        const string* op (path_);
-        path_ = &path_pool.find (diag_relative (p)); // Relative to work.
+        const path* op (path_);
+        path_ = &p;
 
         lexer l (ifs, *path_);
         lexer* ol (lexer_);
@@ -1899,11 +1899,11 @@ namespace build2
   }
 
   buildspec parser::
-  parse_buildspec (istream& is, const std::string& name)
+  parse_buildspec (istream& is, const path& name)
   {
-    path_ = &name; // Note: caller pools.
+    path_ = &name;
 
-    lexer l (is, name, &paren_processor);
+    lexer l (is, *path_, &paren_processor);
     lexer_ = &l;
     target_ = nullptr;
     scope_ = root_ = global_scope;
@@ -2232,8 +2232,8 @@ namespace build2
   static location
   get_location (const token& t, const void* data)
   {
-    assert (data != nullptr);
-    const string& p (**static_cast<const string* const*> (data));
-    return location (p.c_str (), t.line, t.column);
+    assert (data != nullptr); // &parser::path_
+    const path* p (*static_cast<const path* const*> (data));
+    return location (p, t.line, t.column);
   }
 }
diff --git a/build2/path-io.cxx b/build2/path-io.cxx
index 81b981b..845b0a3 100644
--- a/build2/path-io.cxx
+++ b/build2/path-io.cxx
@@ -16,14 +16,14 @@ namespace build2
   ostream&
   operator<< (ostream& os, const path& p)
   {
-    return os << (relative (os) ? diag_relative (p) : p.string ());
+    return os << (stream_verb (os) < 2 ? diag_relative (p) : p.string ());
   }
 
   ostream&
   operator<< (ostream& os, const dir_path& d)
   {
-    if (relative (os))
-      os << diag_relative (d);
+    if (stream_verb (os) < 2)
+      os << diag_relative (d); // Adds trailing '/'.
     else
     {
       const string& s (d.string ());
diff --git a/build2/prerequisite.cxx b/build2/prerequisite.cxx
index 2192abe..fb432eb 100644
--- a/build2/prerequisite.cxx
+++ b/build2/prerequisite.cxx
@@ -22,16 +22,26 @@ namespace build2
   {
     if (pk.proj != nullptr)
       os << *pk.proj << '%';
-
-    // Don't print scope if we are project-qualified or the
-    // prerequisite's directory is absolute. In both these
-    // cases the scope is not used to resolve it to target.
+    //
+    // Don't print scope if we are project-qualified or the prerequisite's
+    // directory is absolute. In both these cases the scope is not used to
+    // resolve it to target.
     //
     else if (!pk.tk.dir->absolute ())
     {
-      string s (diag_relative (pk.scope->out_path (), false));
+      // Avoid printing './' in './:...', similar to what we do for the
+      // directory in target_key.
+      //
+      const dir_path& s (pk.scope->out_path ());
+
+      if (stream_verb (os) < 2)
+      {
+        const string& r (diag_relative (s, false));
 
-      if (!s.empty ())
+        if (!r.empty ())
+          os << r << ':';
+      }
+      else
         os << s << ':';
     }
 
diff --git a/build2/spec.cxx b/build2/spec.cxx
index 89ed9c8..3f02d87 100644
--- a/build2/spec.cxx
+++ b/build2/spec.cxx
@@ -18,10 +18,18 @@ namespace build2
   {
     if (!s.src_base.empty ())
     {
-      string d (diag_relative (s.src_base, false));
-
-      if (!d.empty ())
-        os << d << '@';
+      // Avoid printing './' in './@...', similar to what we do for the
+      // {target,prerequisite}_key.
+      //
+      if (stream_verb (os) < 2)
+      {
+        const string& r (diag_relative (s.src_base, false));
+
+        if (!r.empty ())
+          os << r << '@';
+      }
+      else
+        os << s.src_base << '@';
     }
 
     os << s.name;
diff --git a/build2/target.cxx b/build2/target.cxx
index 0dcf959..43c6a41 100644
--- a/build2/target.cxx
+++ b/build2/target.cxx
@@ -254,10 +254,16 @@ namespace build2
     // inside {}, e.g., dir{bar/}, not bar/dir{}.
     //
     bool n (!k.name->empty ());
-    string d (diag_relative (*k.dir, false));
 
     if (n)
-      os << d;
+    {
+      // Avoid printing './' in './{...}'
+      //
+      if (stream_verb (os) < 2)
+        os << diag_relative (*k.dir, false);
+      else
+        os << *k.dir;
+    }
 
     os << k.type->name << '{';
 
@@ -269,7 +275,7 @@ namespace build2
         os << '.' << *k.ext;
     }
     else
-      os << d;
+      os << *k.dir;
 
     os << '}';
 
diff --git a/build2/types b/build2/types
index 407a3b5..35aaa58 100644
--- a/build2/types
+++ b/build2/types
@@ -5,11 +5,13 @@
 #ifndef BUILD2_TYPES
 #define BUILD2_TYPES
 
+#include <iosfwd>      // ostream
 #include <vector>
 #include <string>
 #include <utility>     // pair
 #include <memory>      // unique_ptr, shared_ptr
 #include <cstddef>     // size_t
+#include <cstdint>     // uint{8,16,32,64}_t
 #include <functional>  // reference_wrapper
 
 #include <butl/path>
@@ -21,8 +23,13 @@ namespace build2
 {
   // Commonly-used types.
   //
-  using std::pair;
+  using std::uint8_t;
+  using std::uint16_t;
+  using std::uint32_t;
+  using std::uint64_t;
   using std::size_t;
+
+  using std::pair;
   using std::string;
   using std::unique_ptr;
   using std::shared_ptr;
@@ -32,6 +39,10 @@ namespace build2
   using strings = vector<string>;
   using cstrings = vector<const char*>;
 
+  // <iosfwd>
+  //
+  using std::ostream;
+
   // <butl/path>
   //
   using butl::path;
-- 
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