Rework diagnostics verbosity, add quiet mode/option

32 files changed, 234 insertions, 156 deletions

diff --git a/build/algorithm.cxx b/build/algorithm.cxx
index 9a2f9fb..fb6c72a 100644
--- a/build/algorithm.cxx
+++ b/build/algorithm.cxx
@@ -234,8 +234,8 @@ namespace build
     diag_record dr;
     dr << fail << "no rule to " << diag_do (a, t);
 
-    if (verb < 3)
-      dr << info << "re-run with --verbose 3 for more information";
+    if (verb < 4)
+      dr << info << "re-run with --verbose 4 for more information";
 
     return r;
   }
@@ -333,7 +333,7 @@ namespace build
     if (!d.sub (out_root) || d == out_root)
       return;
 
-    level5 ([&]{trace << "for " << t;});
+    level6 ([&]{trace << "for " << t;});
 
     fsdir& dt (search<fsdir> (d, string (), nullptr, &s));
     match (a, dt);
diff --git a/build/b.cxx b/build/b.cxx
index 2264c62..bbfc635 100644
--- a/build/b.cxx
+++ b/build/b.cxx
@@ -84,9 +84,11 @@ main (int argc, char* argv[])
       return 0;
     }
 
-    // Trace verbosity.
+    // Diagnostics verbosity.
     //
-    verb = ops.verbose () > 0 ? ops.verbose () : (ops.v () ? 1 : 0);
+    verb = ops.verbose_specified ()
+      ? ops.verbose ()
+      : ops.v () ? 2 : ops.q () ? 0 : 1;
 
     // Initialize time conversion data that is used by localtime_r().
     //
@@ -121,7 +123,7 @@ main (int argc, char* argv[])
       home = dir_path (pw->pw_dir);
     }
 
-    if (verb >= 4)
+    if (verb >= 5)
     {
       trace << "work dir: " << work;
       trace << "home dir: " << home;
@@ -198,7 +200,7 @@ main (int argc, char* argv[])
       }
     }
 
-    level4 ([&]{trace << "buildspec: " << bspec;});
+    level5 ([&]{trace << "buildspec: " << bspec;});
 
     if (bspec.empty ())
       bspec.push_back (metaopspec ()); // Default meta-operation.
@@ -244,7 +246,7 @@ main (int argc, char* argv[])
           if (mif->meta_operation_post != nullptr)
             mif->meta_operation_post ();
 
-          level4 ([&]{trace << "end meta-operation batch " << mif->name
+          level5 ([&]{trace << "end meta-operation batch " << mif->name
                             << ", id " << static_cast<uint16_t> (mid);});
 
           mid = 0;
@@ -532,7 +534,7 @@ main (int argc, char* argv[])
                     if (mif->meta_operation_post != nullptr)
                       mif->meta_operation_post ();
 
-                    level4 ([&]{trace << "end meta-operation batch "
+                    level5 ([&]{trace << "end meta-operation batch "
                                       << mif->name << ", id "
                                       << static_cast<uint16_t> (mid);});
 
@@ -598,7 +600,7 @@ main (int argc, char* argv[])
                 fail (l) << "target " << tn << " does not support meta-"
                          << "operation " << meta_operation_table[m];
 
-              level4 ([&]{trace << "start meta-operation batch " << mif->name
+              level5 ([&]{trace << "start meta-operation batch " << mif->name
                                 << ", id " << static_cast<uint16_t> (mid);});
 
               if (mif->meta_operation_pre != nullptr)
@@ -644,7 +646,7 @@ main (int argc, char* argv[])
 
               oif = lookup (o);
 
-              level4 ([&]{trace << "start operation batch " << oif->name
+              level5 ([&]{trace << "start operation batch " << oif->name
                                 << ", id " << static_cast<uint16_t> (o);});
 
               // Allow the meta-operation to translate the operation.
@@ -657,7 +659,7 @@ main (int argc, char* argv[])
               if (o != oid)
               {
                 oif = lookup (oid);
-                level4 ([&]{trace << "operation translated to " << oif->name
+                level5 ([&]{trace << "operation translated to " << oif->name
                                   << ", id " << static_cast<uint16_t> (oid);});
               }
 
@@ -705,7 +707,7 @@ main (int argc, char* argv[])
             }
           }
 
-          if (verb >= 4)
+          if (verb >= 5)
           {
             trace << "target " << tn << ':';
             trace << "  out_base: " << out_base;
@@ -757,7 +759,7 @@ main (int argc, char* argv[])
 
         if (pre_oid != 0)
         {
-          level4 ([&]{trace << "start pre-operation batch " << pre_oif->name
+          level5 ([&]{trace << "start pre-operation batch " << pre_oif->name
                             << ", id " << static_cast<uint16_t> (pre_oid);});
 
           if (mif->operation_pre != nullptr)
@@ -776,7 +778,7 @@ main (int argc, char* argv[])
           if (mif->operation_post != nullptr)
             mif->operation_post (pre_oid);
 
-          level4 ([&]{trace << "end pre-operation batch " << pre_oif->name
+          level5 ([&]{trace << "end pre-operation batch " << pre_oif->name
                             << ", id " << static_cast<uint16_t> (pre_oid);});
         }
 
@@ -788,11 +790,11 @@ main (int argc, char* argv[])
         action a (mid, oid, 0);
 
         mif->match (a, tgs);
-        mif->execute (a, tgs, false);
+        mif->execute (a, tgs, verb == 0);
 
         if (post_oid != 0)
         {
-          level4 ([&]{trace << "start post-operation batch " << post_oif->name
+          level5 ([&]{trace << "start post-operation batch " << post_oif->name
                             << ", id " << static_cast<uint16_t> (post_oid);});
 
           if (mif->operation_pre != nullptr)
@@ -811,21 +813,21 @@ main (int argc, char* argv[])
           if (mif->operation_post != nullptr)
             mif->operation_post (post_oid);
 
-          level4 ([&]{trace << "end post-operation batch " << post_oif->name
+          level5 ([&]{trace << "end post-operation batch " << post_oif->name
                             << ", id " << static_cast<uint16_t> (post_oid);});
         }
 
         if (mif->operation_post != nullptr)
           mif->operation_post (oid);
 
-        level4 ([&]{trace << "end operation batch " << oif->name
+        level5 ([&]{trace << "end operation batch " << oif->name
                           << ", id " << static_cast<uint16_t> (oid);});
       }
 
       if (mif->meta_operation_post != nullptr)
         mif->meta_operation_post ();
 
-      level4 ([&]{trace << "end meta-operation batch " << mif->name
+      level5 ([&]{trace << "end meta-operation batch " << mif->name
                         << ", id " << static_cast<uint16_t> (mid);});
     }
   }
diff --git a/build/bin/module.cxx b/build/bin/module.cxx
index ba10181..25700c6 100644
--- a/build/bin/module.cxx
+++ b/build/bin/module.cxx
@@ -37,7 +37,7 @@ namespace build
               bool first)
     {
       tracer trace ("bin::init");
-      level4 ([&]{trace << "for " << b.out_path ();});
+      level5 ([&]{trace << "for " << b.out_path ();});
 
       // Register target types.
       //
diff --git a/build/buildfile b/build/buildfile
index a9fcc49..f4320d4 100644
--- a/build/buildfile
+++ b/build/buildfile
@@ -19,4 +19,4 @@ exe{b}: cxx{b algorithm name operation spec scope variable target \
 
 #@@ TODO
 #
-# cli --cli-namespace cl --include-with-brackets --include-prefix build --guard-prefix BUILD --hxx-suffix "" options.cli
+# cli --generate-specifier --cli-namespace cl --include-with-brackets --include-prefix build --guard-prefix BUILD --hxx-suffix "" options.cli
diff --git a/build/cli/module.cxx b/build/cli/module.cxx
index f8d1522..240aaa7 100644
--- a/build/cli/module.cxx
+++ b/build/cli/module.cxx
@@ -36,7 +36,7 @@ namespace build
               bool first)
     {
       tracer trace ("cli::init");
-      level4 ([&]{trace << "for " << base.out_path ();});
+      level5 ([&]{trace << "for " << base.out_path ();});
 
       // Make sure the cxx module has been loaded since we need its
       // targets types (?xx{}). Note that we don't try to load it
@@ -104,9 +104,9 @@ namespace build
           const string& cli (as<string> (p.first));
           const char* args[] = {cli.c_str (), "--version", nullptr};
 
-          if (verb)
+          if (verb >= 2)
             print_process (args);
-          else
+          else if (verb)
             text << "test " << cli;
 
           string ver;
@@ -141,7 +141,7 @@ namespace build
             throw failed ();
           }
 
-          if (verb)
+          if (verb >= 2)
             text << cli << " " << ver;
         }
       }
diff --git a/build/cli/rule.cxx b/build/cli/rule.cxx
index 8b0ba85..ef3b1dc 100644
--- a/build/cli/rule.cxx
+++ b/build/cli/rule.cxx
@@ -46,7 +46,7 @@ namespace build
             //
             if (t.name != p.name ())
             {
-              level3 ([&]{trace << ".cli file stem '" << p.name () << "' "
+              level4 ([&]{trace << ".cli file stem '" << p.name () << "' "
                                 << "doesn't match target " << t;});
               return r;
             }
@@ -58,7 +58,7 @@ namespace build
 
         if (!r)
         {
-          level3 ([&]{trace << "no .cli source file for target " << t;});
+          level4 ([&]{trace << "no .cli source file for target " << t;});
           return r;
         }
 
@@ -117,7 +117,7 @@ namespace build
                 g->prerequisites.emplace_back (p.as_prerequisite (trace));
               }
               else
-                level3 ([&]{trace << ".cli file stem '" << p.name () << "' "
+                level4 ([&]{trace << ".cli file stem '" << p.name () << "' "
                                   << "doesn't match target " << t;});
               break;
             }
@@ -135,7 +135,7 @@ namespace build
           //
           if (t.is_a<cxx::ixx> () && g->i == nullptr)
           {
-            level3 ([&]{trace << "generation of inline file " << t
+            level4 ([&]{trace << "generation of inline file " << t
                               << " is disabled with --suppress-inline";});
             g = nullptr;
           }
@@ -245,9 +245,9 @@ namespace build
       args.push_back (rels.string ().c_str ());
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "cli " << *s;
 
       try
diff --git a/build/config/module.cxx b/build/config/module.cxx
index 74bcec4..bb787a0 100644
--- a/build/config/module.cxx
+++ b/build/config/module.cxx
@@ -43,7 +43,7 @@ namespace build
       }
 
       const dir_path& out_root (r.out_path ());
-      level4 ([&]{trace << "for " << out_root;});
+      level5 ([&]{trace << "for " << out_root;});
 
       // Register meta-operations.
       //
diff --git a/build/config/operation.cxx b/build/config/operation.cxx
index 424fd46..9d7c9b3 100644
--- a/build/config/operation.cxx
+++ b/build/config/operation.cxx
@@ -40,7 +40,8 @@ namespace build
     {
       path f (out_root / src_root_file);
 
-      text << (verb ? "config::save_src_root " : "save ") << f;
+      if (verb)
+        text << (verb >= 2 ? "config::save_src_root " : "save ") << f;
 
       try
       {
@@ -68,7 +69,8 @@ namespace build
       const dir_path& out_root (root.out_path ());
       path f (out_root / config_file);
 
-      text << (verb ? "config::save_config " : "save ") << f;
+      if (verb)
+        text << (verb >= 2 ? "config::save_config " : "save ") << f;
 
       try
       {
@@ -151,7 +153,7 @@ namespace build
       //
       if (a.operation () == default_id)
       {
-        level4 ([&]{trace << "completely configuring " << out_root;});
+        level5 ([&]{trace << "completely configuring " << out_root;});
 
         // Save src-root.build unless out_root is the same as src.
         //
@@ -263,7 +265,7 @@ namespace build
                     const location&)
     {
       tracer trace ("disfigure_load");
-      level5 ([&]{trace << "skipping " << bf;});
+      level6 ([&]{trace << "skipping " << bf;});
     }
 
     static void
@@ -273,7 +275,7 @@ namespace build
                       action_targets& ts)
     {
       tracer trace ("disfigure_search");
-      level5 ([&]{trace << "collecting " << root.out_path ();});
+      level6 ([&]{trace << "collecting " << root.out_path ();});
       ts.push_back (&root);
     }
 
@@ -345,7 +347,7 @@ namespace build
       //
       if (a.operation () == default_id)
       {
-        level4 ([&]{trace << "completely disfiguring " << out_root;});
+        level5 ([&]{trace << "completely disfiguring " << out_root;});
 
         m = rmfile (out_root / config_file) || m;
 
@@ -414,7 +416,7 @@ namespace build
       // Reset the dependency state since anything that could have been
       // loaded earlier using a previous configuration is now invalid.
       //
-      level5 ([&]{trace << "resetting dependency state";});
+      level6 ([&]{trace << "resetting dependency state";});
       reset ();
     }
 
diff --git a/build/context.cxx b/build/context.cxx
index fa1ea8f..5a801b0 100644
--- a/build/context.cxx
+++ b/build/context.cxx
@@ -126,12 +126,17 @@ namespace build
     }
     catch (const system_error& e)
     {
-      text << "mkdir " << d;
+      if (verb)
+        text << "mkdir " << d;
+
       fail << "unable to create directory " << d << ": " << e.what ();
     }
 
     if (ms == mkdir_status::success)
-      text << "mkdir " << d;
+    {
+      if (verb)
+        text << "mkdir " << d;
+    }
 
     return ms;
   }
@@ -150,12 +155,17 @@ namespace build
     }
     catch (const system_error& e)
     {
-      text << "mkdir -p " << d;
+      if (verb)
+        text << "mkdir -p " << d;
+
       fail << "unable to create directory " << d << ": " << e.what ();
     }
 
     if (ms == mkdir_status::success)
-      text << "mkdir -p " << d;
+    {
+      if (verb)
+        text << "mkdir -p " << d;
+    }
 
     return ms;
   }
@@ -171,7 +181,8 @@ namespace build
     if (!dir_exists (d))
       return rmdir_status::not_exist;
 
-    text << "rmdir -r " << d;
+    if (verb)
+      text << "rmdir -r " << d;
 
     try
     {
diff --git a/build/context.txx b/build/context.txx
index eb1568c..a0660f9 100644
--- a/build/context.txx
+++ b/build/context.txx
@@ -27,9 +27,9 @@ namespace build
     }
     catch (const std::system_error& e)
     {
-      if (verb)
+      if (verb >= 2)
         text << "rm " << f;
-      else
+      else if (verb)
         text << "rm " << t;
 
       fail << "unable to remove file " << f << ": " << e.what ();
@@ -37,9 +37,9 @@ namespace build
 
     if (rs == rmfile_status::success)
     {
-      if (verb)
+      if (verb >= 2)
         text << "rm " << f;
-      else
+      else if (verb)
         text << "rm " << t;
     }
 
@@ -66,9 +66,9 @@ namespace build
     }
     catch (const std::system_error& e)
     {
-      if (verb)
+      if (verb >= 2)
         text << "rmdir " << d;
-      else
+      else if (verb)
         text << "rmdir " << t;
 
       fail << "unable to remove directory " << d << ": " << e.what ();
@@ -78,16 +78,16 @@ namespace build
     {
     case rmdir_status::success:
       {
-        if (verb)
+        if (verb >= 2)
           text << "rmdir " << d;
-        else
+        else if (verb)
           text << "rmdir " << t;
 
         break;
       }
     case rmdir_status::not_empty:
       {
-        if (verb)
+        if (verb >= 2)
           text << "directory " << d << " is "
                << (w ? "current working directory" : "not empty")
                << ", not removing";
diff --git a/build/cxx/compile.cxx b/build/cxx/compile.cxx
index 9a3e3d7..d986cac 100644
--- a/build/cxx/compile.cxx
+++ b/build/cxx/compile.cxx
@@ -58,7 +58,7 @@ namespace build
           return p;
       }
 
-      level3 ([&]{trace << "no c++ source file for target " << t;});
+      level4 ([&]{trace << "no c++ source file for target " << t;});
       return nullptr;
     }
 
@@ -236,7 +236,7 @@ namespace build
           else
             continue;
 
-          level5 ([&]{trace << "-I '" << d << "'";});
+          level6 ([&]{trace << "-I '" << d << "'";});
 
           // If we are relative or not inside our project root, then
           // ignore.
@@ -268,7 +268,7 @@ namespace build
               // be reasonably expected to work according to the order
               // of the -I options.
               //
-              if (verb >= 3)
+              if (verb >= 4)
                 trace << "overriding dependency prefix '" << p << "'\n"
                       << "  old mapping to " << j->second << "\n"
                       << "  new mapping to " << d;
@@ -278,7 +278,7 @@ namespace build
           }
           else
           {
-            level5 ([&]{trace << "'" << p << "' = '" << d << "'";});
+            level6 ([&]{trace << "'" << p << "' = '" << d << "'";});
             m.emplace (move (p), move (d));
           }
         }
@@ -418,7 +418,7 @@ namespace build
       args.push_back (s.path ().string ().c_str ());
       args.push_back (nullptr);
 
-      level5 ([&]{trace << "target: " << t;});
+      level6 ([&]{trace << "target: " << t;});
 
       // Build the prefix map lazily only if we have non-existent files.
       // Also reuse it over restarts since it doesn't change.
@@ -461,7 +461,7 @@ namespace build
       {
         restart = false;
 
-        if (verb >= 2)
+        if (verb >= 3)
           print_process (args);
 
         try
@@ -539,9 +539,9 @@ namespace build
               if (!f.absolute ())
               {
                 // This is probably as often an error as an auto-generated
-                // file, so trace at level 3.
+                // file, so trace at level 4.
                 //
-                level3 ([&]{trace << "non-existent header '" << f << "'";});
+                level4 ([&]{trace << "non-existent header '" << f << "'";});
 
                 // If we already did it and build_prefix_map() returned empty,
                 // then we would have failed below.
@@ -582,7 +582,7 @@ namespace build
                 f = i->second / f;
               }
 
-              level5 ([&]{trace << "injecting " << f;});
+              level6 ([&]{trace << "injecting " << f;});
 
               // Split the name into its directory part, the name part, and
               // extension. Here we can assume the name part is a valid
@@ -667,7 +667,7 @@ namespace build
 
                 if (ns != os && ns != target_state::unchanged)
                 {
-                  level5 ([&]{trace << "updated " << pt << ", restarting";});
+                  level6 ([&]{trace << "updated " << pt << ", restarting";});
                   restart = true;
                 }
               }
@@ -754,9 +754,9 @@ namespace build
 
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "c++ " << *s;
 
       try
diff --git a/build/cxx/link.cxx b/build/cxx/link.cxx
index 2554930..6742ff2 100644
--- a/build/cxx/link.cxx
+++ b/build/cxx/link.cxx
@@ -113,7 +113,7 @@ namespace build
       args.push_back ("-print-search-dirs");
       args.push_back (nullptr);
 
-      if (verb >= 5)
+      if (verb >= 3)
         print_process (args);
 
       string l;
@@ -399,7 +399,7 @@ namespace build
       //
       if (seen_c && !seen_cxx && hint < "cxx")
       {
-        level3 ([&]{trace << "c prerequisite(s) without c++ or hint";});
+        level4 ([&]{trace << "c prerequisite(s) without c++ or hint";});
         return nullptr;
       }
 
@@ -807,9 +807,9 @@ namespace build
 
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "ld " << t;
 
       try
diff --git a/build/cxx/module.cxx b/build/cxx/module.cxx
index 6b7da80..eda3593 100644
--- a/build/cxx/module.cxx
+++ b/build/cxx/module.cxx
@@ -35,7 +35,7 @@ namespace build
               bool first)
     {
       tracer trace ("cxx::init");
-      level4 ([&]{trace << "for " << b.out_path ();});
+      level5 ([&]{trace << "for " << b.out_path ();});
 
       // Initialize the bin module. Only do this if it hasn't already
       // been loaded so that we don't overwrite user's bin.* settings.
@@ -148,9 +148,9 @@ namespace build
           const string& cxx (as<string> (p.first));
           const char* args[] = {cxx.c_str (), "-dumpversion", nullptr};
 
-          if (verb)
+          if (verb >= 2)
             print_process (args);
-          else
+          else if (verb)
             text << "test " << cxx;
 
           string ver;
@@ -177,7 +177,7 @@ namespace build
             throw failed ();
           }
 
-          if (verb)
+          if (verb >= 2)
             text << cxx << " " << ver;
         }
       }
diff --git a/build/diagnostics b/build/diagnostics
index ab4c4a2..6e54f56 100644
--- a/build/diagnostics
+++ b/build/diagnostics
@@ -94,14 +94,15 @@ namespace build
     print_process (args.data (), args.size ());
   }
 
-  // Trace verbosity level.
+  // Verbosity level.
   //
-  // 0 - tracing disabled.
-  // 1 - command lines to update explicit targets (e.g., .o)
-  // 2 - command lines to update implicit targets (e.g., .d)
-  // 3 - things didn't work out (e.g., rule did not match)
-  // 4 - additional information
-  // 5 - more additional information
+  // 0 - disabled
+  // 1 - high-level information messages
+  // 2 - essential underlying commands that are being executed
+  // 3 - all underlying commands that are being executed
+  // 4 - information helpful to the user (e.g., why a rule did not match)
+  // 5 - information helpful to the developer
+  // 6 - even more detailed information
   //
   // While uint8 is more than enough, use uint16 for the ease of printing.
   //
@@ -112,6 +113,7 @@ namespace build
   template <typename F> inline void level3 (const F& f) {if (verb >= 3) f ();}
   template <typename F> inline void level4 (const F& f) {if (verb >= 4) f ();}
   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 ();}
 
   // Diagnostic facility, base infrastructure (potentially reusable).
   //
@@ -315,7 +317,7 @@ namespace build
   // 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 0.
+  // relative unless verbosity is greater than 1.
   //
   struct basic_mark_base
   {
@@ -364,7 +366,7 @@ namespace build
     simple_prologue
     operator() () const
     {
-      return simple_prologue (type_, name_, verb == 0);
+      return simple_prologue (type_, name_, verb <= 1);
     }
   };
   typedef diag_mark<text_mark_base> text_mark;
diff --git a/build/diagnostics.cxx b/build/diagnostics.cxx
index 2f9525b..075dbab 100644
--- a/build/diagnostics.cxx
+++ b/build/diagnostics.cxx
@@ -203,7 +203,7 @@ namespace build
     } while (*p != nullptr);
   }
 
-  // Trace verbosity level.
+  // Diagnostics verbosity level.
   //
   uint16_t verb;
 
diff --git a/build/dist/module.cxx b/build/dist/module.cxx
index 48c1fd0..0b60fa8 100644
--- a/build/dist/module.cxx
+++ b/build/dist/module.cxx
@@ -41,7 +41,7 @@ namespace build
       }
 
       const dir_path& out_root (r.out_path ());
-      level4 ([&]{trace << "for " << out_root;});
+      level5 ([&]{trace << "for " << out_root;});
 
       // Register meta-operation.
       //
diff --git a/build/dist/operation.cxx b/build/dist/operation.cxx
index c4d022b..3928759 100644
--- a/build/dist/operation.cxx
+++ b/build/dist/operation.cxx
@@ -132,7 +132,7 @@ namespace build
 
         action a (dist_id, id);
 
-        if (verb >= 5)
+        if (verb >= 6)
           dump (a);
 
         for (void* v: ts)
@@ -142,12 +142,12 @@ namespace build
           if (rs != t.base_scope ().root_scope ())
             fail << "out of project target " << t;
 
-          level4 ([&]{trace << diag_doing (a, t);});
+          level5 ([&]{trace << diag_doing (a, t);});
 
           match (a, t);
         }
 
-        if (verb >= 5)
+        if (verb >= 6)
           dump (a);
       }
 
@@ -283,9 +283,9 @@ namespace build
       args.push_back (reld.string ().c_str ());
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "dist -d " << d;
 
       try
@@ -337,9 +337,9 @@ namespace build
       args.push_back (reld.string ().c_str ());
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "dist " << t;
 
       try
@@ -380,9 +380,9 @@ namespace build
       else
         args = {"tar", "-a", "-cf", a.c_str (), pkg.c_str (), nullptr};
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << args[0] << " " << ap;
 
       try
diff --git a/build/file.cxx b/build/file.cxx
index 435746c..f8f62f9 100644
--- a/build/file.cxx
+++ b/build/file.cxx
@@ -83,7 +83,7 @@ namespace build
     if (!ifs.is_open ())
       fail << "unable to open " << bf;
 
-    level4 ([&]{trace << "sourcing " << bf;});
+    level5 ([&]{trace << "sourcing " << bf;});
 
     ifs.exceptions (ifstream::failbit | ifstream::badbit);
     parser p;
@@ -105,7 +105,7 @@ namespace build
 
     if (!once.buildfiles.insert (bf).second)
     {
-      level4 ([&]{trace << "skipping already sourced " << bf;});
+      level5 ([&]{trace << "skipping already sourced " << bf;});
       return;
     }
 
@@ -327,7 +327,7 @@ namespace build
       {
         src_root_v = extract_variable (f, "src_root");
         src_root = &as<dir_path> (src_root_v);
-        level4 ([&]{trace << "extracted src_root " << *src_root << " for "
+        level5 ([&]{trace << "extracted src_root " << *src_root << " for "
                           << out_root;});
       }
     }
@@ -338,7 +338,7 @@ namespace build
       name = move (as<string> (v));
     }
 
-    level4 ([&]{trace << "extracted project name " << name << " for "
+    level5 ([&]{trace << "extracted project name " << name << " for "
                       << *src_root;});
     return name;
   }
@@ -372,7 +372,7 @@ namespace build
       // Calculate relative subdirectory for this subproject.
       //
       dir_path dir (sd.leaf (root));
-      level4 ([&]{trace << "subproject " << sd << " as " << dir;});
+      level5 ([&]{trace << "subproject " << sd << " as " << dir;});
 
       // Load its name. Note that here we don't use fallback src_root
       // since this function is used to scan both out_root and src_root.
@@ -395,7 +395,7 @@ namespace build
             info << "first alternative: " << dir1 <<
             info << "second alternative: " << dir;
 
-        level5 ([&]{trace << "skipping duplicate";});
+        level6 ([&]{trace << "skipping duplicate";});
       }
     }
   }
@@ -472,7 +472,7 @@ namespace build
         {
           // Otherwise, use the outer root as our amalgamation.
           //
-          level4 ([&]{trace << out_root << " amalgamated as " << rd;});
+          level5 ([&]{trace << out_root << " amalgamated as " << rd;});
           v = move (rd);
         }
       }
@@ -488,7 +488,7 @@ namespace build
         if (!ad.empty ())
         {
           dir_path rd (ad.relative (out_root));
-          level4 ([&]{trace << out_root << " amalgamated as " << rd;});
+          level5 ([&]{trace << out_root << " amalgamated as " << rd;});
           v = move (rd);
         }
       }
@@ -795,7 +795,7 @@ namespace build
         // a stab at it.
         //
         target.proj = &project;
-        level4 ([&]{trace << "postponing " << target;});
+        level5 ([&]{trace << "postponing " << target;});
         return names {move (target)};
       }
     }
@@ -872,7 +872,7 @@ namespace build
     if (!ifs.is_open ())
       fail (loc) << "unable to open " << es;
 
-    level4 ([&]{trace << "importing " << es;});
+    level5 ([&]{trace << "importing " << es;});
 
     ifs.exceptions (ifstream::failbit | ifstream::badbit);
     parser p;
diff --git a/build/install/module.cxx b/build/install/module.cxx
index 454ff3e..b117e98 100644
--- a/build/install/module.cxx
+++ b/build/install/module.cxx
@@ -110,7 +110,7 @@ namespace build
       }
 
       const dir_path& out_root (r.out_path ());
-      level4 ([&]{trace << "for " << out_root;});
+      level5 ([&]{trace << "for " << out_root;});
 
       // Register the install operation.
       //
diff --git a/build/install/rule.cxx b/build/install/rule.cxx
index b1627be..64df3eb 100644
--- a/build/install/rule.cxx
+++ b/build/install/rule.cxx
@@ -178,9 +178,9 @@ namespace build
       args.push_back (reld.string ().c_str ());
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "install " << d;
 
       try
@@ -220,9 +220,9 @@ namespace build
       args.push_back (reld.string ().c_str ());
       args.push_back (nullptr);
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "install " << t;
 
       try
diff --git a/build/operation.cxx b/build/operation.cxx
index 9cc8025..b92479b 100644
--- a/build/operation.cxx
+++ b/build/operation.cxx
@@ -93,17 +93,17 @@ namespace build
   {
     tracer trace ("match");
 
-    if (verb >= 5)
+    if (verb >= 6)
       dump (a);
 
     for (void* vt: ts)
     {
       target& t (*static_cast<target*> (vt));
-      level4 ([&]{trace << "matching " << t;});
+      level5 ([&]{trace << "matching " << t;});
       match (a, t);
     }
 
-    if (verb >= 5)
+    if (verb >= 6)
       dump (a);
   }
 
@@ -122,7 +122,7 @@ namespace build
       {
         target& t (*static_cast<target*> (v));
 
-        level4 ([&]{trace << diag_doing (a, t);});
+        level5 ([&]{trace << diag_doing (a, t);});
 
         switch (execute (a, t))
         {
diff --git a/build/options b/build/options
index c0b9930..a2fea2c 100644
--- a/build/options
+++ b/build/options
@@ -208,6 +208,8 @@ namespace cl
 class options
 {
   public:
+  options ();
+
   options (int& argc,
            char** argv,
            bool erase = false,
@@ -240,8 +242,6 @@ class options
            ::cl::unknown_mode option = ::cl::unknown_mode::fail,
            ::cl::unknown_mode argument = ::cl::unknown_mode::stop);
 
-  options ();
-
   // Option accessors.
   //
   const bool&
@@ -253,9 +253,15 @@ class options
   const bool&
   v () const;
 
+  const bool&
+  q () const;
+
   const std::uint16_t&
   verbose () const;
 
+  bool
+  verbose_specified () const;
+
   // Print usage information.
   //
   static void
@@ -277,7 +283,9 @@ class options
   bool help_;
   bool version_;
   bool v_;
+  bool q_;
   std::uint16_t verbose_;
+  bool verbose_specified_;
 };
 
 #include <build/options.ixx>
diff --git a/build/options.cli b/build/options.cli
index 67eeba2..9bd1dcd 100644
--- a/build/options.cli
+++ b/build/options.cli
@@ -12,13 +12,20 @@ class options
   bool -v
   {
     "Print actual commands being executed. This is equivalent to
-     \cb{--verbose 1}."
+     \cb{--verbose 2}."
   };
 
-  std::uint16_t --verbose = 0
+  bool -q
+  {
+    "Run quietly, only printing error messages. This is equivalent
+     to \cb{--verbose 0}."
+  };
+
+  std::uint16_t --verbose = 1
   {
     "<level>",
-    "Set the diagnostics verbosity to a level between 0 (disabled) and
-     5 (lots of information). @@ Need to document further."
+    "Set the diagnostics verbosity to <level> between 0 (disabled) and
+     6 (lots of information). The default is 1. @@ Need to document
+     further."
   };
 };
diff --git a/build/options.cxx b/build/options.cxx
index 3c1e194..b5c2754 100644
--- a/build/options.cxx
+++ b/build/options.cxx
@@ -172,7 +172,7 @@ namespace cl
   struct parser
   {
     static void
-    parse (X& x, scanner& s)
+    parse (X& x, bool& xs, scanner& s)
     {
       std::string o (s.next ());
 
@@ -185,6 +185,8 @@ namespace cl
       }
       else
         throw missing_value (o);
+
+      xs = true;
     }
   };
 
@@ -203,7 +205,7 @@ namespace cl
   struct parser<std::string>
   {
     static void
-    parse (std::string& x, scanner& s)
+    parse (std::string& x, bool& xs, scanner& s)
     {
       const char* o (s.next ());
 
@@ -211,6 +213,8 @@ namespace cl
         x = s.next ();
       else
         throw missing_value (o);
+
+      xs = true;
     }
   };
 
@@ -218,11 +222,13 @@ namespace cl
   struct parser<std::vector<X> >
   {
     static void
-    parse (std::vector<X>& c, scanner& s)
+    parse (std::vector<X>& c, bool& xs, scanner& s)
     {
       X x;
-      parser<X>::parse (x, s);
+      bool dummy;
+      parser<X>::parse (x, dummy, s);
       c.push_back (x);
+      xs = true;
     }
   };
 
@@ -230,11 +236,13 @@ namespace cl
   struct parser<std::set<X> >
   {
     static void
-    parse (std::set<X>& c, scanner& s)
+    parse (std::set<X>& c, bool& xs, scanner& s)
     {
       X x;
-      parser<X>::parse (x, s);
+      bool dummy;
+      parser<X>::parse (x, dummy, s);
       c.insert (x);
+      xs = true;
     }
   };
 
@@ -242,7 +250,7 @@ namespace cl
   struct parser<std::map<K, V> >
   {
     static void
-    parse (std::map<K, V>& m, scanner& s)
+    parse (std::map<K, V>& m, bool& xs, scanner& s)
     {
       std::string o (s.next ());
 
@@ -293,6 +301,8 @@ namespace cl
       }
       else
         throw missing_value (o);
+
+      xs = true;
     }
   };
 
@@ -302,6 +312,13 @@ namespace cl
   {
     parser<T>::parse (x.*M, s);
   }
+
+  template <typename X, typename T, T X::*M, bool X::*S>
+  void
+  thunk (X& x, scanner& s)
+  {
+    parser<T>::parse (x.*M, x.*S, s);
+  }
 }
 
 #include <map>
@@ -315,7 +332,9 @@ options ()
 : help_ (),
   version_ (),
   v_ (),
-  verbose_ (0)
+  q_ (),
+  verbose_ (1),
+  verbose_specified_ (false)
 {
 }
 
@@ -328,7 +347,9 @@ options (int& argc,
 : help_ (),
   version_ (),
   v_ (),
-  verbose_ (0)
+  q_ (),
+  verbose_ (1),
+  verbose_specified_ (false)
 {
   ::cl::argv_scanner s (argc, argv, erase);
   _parse (s, opt, arg);
@@ -344,7 +365,9 @@ options (int start,
 : help_ (),
   version_ (),
   v_ (),
-  verbose_ (0)
+  q_ (),
+  verbose_ (1),
+  verbose_specified_ (false)
 {
   ::cl::argv_scanner s (start, argc, argv, erase);
   _parse (s, opt, arg);
@@ -360,7 +383,9 @@ options (int& argc,
 : help_ (),
   version_ (),
   v_ (),
-  verbose_ (0)
+  q_ (),
+  verbose_ (1),
+  verbose_specified_ (false)
 {
   ::cl::argv_scanner s (argc, argv, erase);
   _parse (s, opt, arg);
@@ -378,7 +403,9 @@ options (int start,
 : help_ (),
   version_ (),
   v_ (),
-  verbose_ (0)
+  q_ (),
+  verbose_ (1),
+  verbose_specified_ (false)
 {
   ::cl::argv_scanner s (start, argc, argv, erase);
   _parse (s, opt, arg);
@@ -392,7 +419,9 @@ options (::cl::scanner& s,
 : help_ (),
   version_ (),
   v_ (),
-  verbose_ (0)
+  q_ (),
+  verbose_ (1),
+  verbose_specified_ (false)
 {
   _parse (s, opt, arg);
 }
@@ -406,8 +435,10 @@ print_usage (::std::ostream& os)
 
   os << "-v                Print actual commands being executed." << ::std::endl;
 
-  os << "--verbose <level> Set the diagnostics verbosity to a level between 0 (disabled)" << ::std::endl
-     << "                  and 5 (lots of information)." << ::std::endl;
+  os << "-q                Run quietly, only printing error messages." << ::std::endl;
+
+  os << "--verbose <level> Set the diagnostics verbosity to <level> between 0 (disabled)" << ::std::endl
+     << "                  and 6 (lots of information)." << ::std::endl;
 }
 
 typedef
@@ -426,8 +457,11 @@ struct _cli_options_map_init
     &::cl::thunk< options, bool, &options::version_ >;
     _cli_options_map_["-v"] = 
     &::cl::thunk< options, bool, &options::v_ >;
+    _cli_options_map_["-q"] = 
+    &::cl::thunk< options, bool, &options::q_ >;
     _cli_options_map_["--verbose"] = 
-    &::cl::thunk< options, std::uint16_t, &options::verbose_ >;
+    &::cl::thunk< options, std::uint16_t, &options::verbose_,
+      &options::verbose_specified_ >;
   }
 };
 
diff --git a/build/options.ixx b/build/options.ixx
index 671f9ec..c44d7e5 100644
--- a/build/options.ixx
+++ b/build/options.ixx
@@ -133,12 +133,24 @@ v () const
   return this->v_;
 }
 
+inline const bool& options::
+q () const
+{
+  return this->q_;
+}
+
 inline const std::uint16_t& options::
 verbose () const
 {
   return this->verbose_;
 }
 
+inline bool options::
+verbose_specified () const
+{
+  return this->verbose_specified_;
+}
+
 // Begin epilogue.
 //
 //
diff --git a/build/parser.cxx b/build/parser.cxx
index 59139ba..6c3e4bc 100644
--- a/build/parser.cxx
+++ b/build/parser.cxx
@@ -442,7 +442,7 @@ namespace build
 
       ifs.exceptions (ifstream::failbit | ifstream::badbit);
 
-      level4 ([&]{trace (t) << "entering " << p;});
+      level5 ([&]{trace (t) << "entering " << p;});
 
       enter_buildfile (p);
 
@@ -462,7 +462,7 @@ namespace build
       if (tt != type::eos)
         fail (t) << "unexpected " << t;
 
-      level4 ([&]{trace (t) << "leaving " << p;});
+      level5 ([&]{trace (t) << "leaving " << p;});
 
       lexer_ = ol;
       path_ = op;
@@ -554,7 +554,7 @@ namespace build
 
       if (!root_->buildfiles.insert (p).second) // Note: may be "new" root.
       {
-        level4 ([&]{trace (l) << "skipping already included " << p;});
+        level5 ([&]{trace (l) << "skipping already included " << p;});
         scope_ = ocs;
         root_ = ors;
         continue;
@@ -567,7 +567,7 @@ namespace build
 
       ifs.exceptions (ifstream::failbit | ifstream::badbit);
 
-      level4 ([&]{trace (t) << "entering " << p;});
+      level5 ([&]{trace (t) << "entering " << p;});
 
       enter_buildfile (p);
 
@@ -592,7 +592,7 @@ namespace build
 
       process_default_target (t);
 
-      level4 ([&]{trace (t) << "leaving " << p;});
+      level5 ([&]{trace (t) << "leaving " << p;});
 
       default_target_ = odt;
       lexer_ = ol;
@@ -1478,7 +1478,7 @@ namespace build
     //
     if (rs != root_)
     {
-      level4 ([&]{trace << "switching to root scope " << rs->out_path ();});
+      level5 ([&]{trace << "switching to root scope " << rs->out_path ();});
       root_ = rs;
     }
 
@@ -1510,7 +1510,7 @@ namespace build
 
     target& dt (*default_target_);
 
-    level4 ([&]{trace (t) << "creating current directory alias for " << dt;});
+    level5 ([&]{trace (t) << "creating current directory alias for " << dt;});
 
     target& ct (
       targets.insert (
diff --git a/build/prerequisite.cxx b/build/prerequisite.cxx
index 1f9f68b..89ac275 100644
--- a/build/prerequisite.cxx
+++ b/build/prerequisite.cxx
@@ -61,7 +61,7 @@ namespace build
     //
     if (p.ext != ext)
     {
-      level4 ([&]{
+      level5 ([&]{
           diag_record r (trace);
           r << "assuming prerequisite " << p << " is the same as the "
             << "one with ";
diff --git a/build/rule.cxx b/build/rule.cxx
index 0fe5e1a..cce291c 100644
--- a/build/rule.cxx
+++ b/build/rule.cxx
@@ -62,7 +62,7 @@ namespace build
         if (ts != timestamp_nonexistent)
           return t;
 
-        level3 ([&]{trace << "no existing file for target " << t;});
+        level4 ([&]{trace << "no existing file for target " << t;});
         return nullptr;
       }
     default:
@@ -201,9 +201,9 @@ namespace build
     //
     if (!dir_exists (d))
     {
-      if (verb)
+      if (verb >= 2)
         text << "mkdir " << d;
-      else
+      else if (verb)
         text << "mkdir " << t;
 
       try
diff --git a/build/search.cxx b/build/search.cxx
index 32302d6..c06d281 100644
--- a/build/search.cxx
+++ b/build/search.cxx
@@ -49,7 +49,7 @@ namespace build
 
     target& t (**i);
 
-    level4 ([&]{trace << "existing target " << t << " for prerequisite "
+    level5 ([&]{trace << "existing target " << t << " for prerequisite "
                       << pk;});
 
     return &t;
@@ -85,7 +85,7 @@ namespace build
         // think.
         //
         //fail << "no default extension for prerequisite " << pk;
-        level3 ([&]{trace << "no existing file found for prerequisite "
+        level4 ([&]{trace << "no existing file found for prerequisite "
                           << pk;});
         return nullptr;
       }
@@ -109,7 +109,7 @@ namespace build
       if (mt == timestamp_nonexistent)
         continue;
 
-      level4 ([&]{trace << "found existing file " << f << " for prerequisite "
+      level5 ([&]{trace << "found existing file " << f << " for prerequisite "
                         << pk;});
 
       // Find or insert. Note: using our updated extension.
@@ -120,7 +120,7 @@ namespace build
       //
       file& t (dynamic_cast<file&> (r.first));
 
-      level4 ([&]{trace << (r.second ? "new" : "existing") << " target "
+      level5 ([&]{trace << (r.second ? "new" : "existing") << " target "
                         << t << " for prerequisite " << pk;});
 
       if (t.path ().empty ())
@@ -130,7 +130,7 @@ namespace build
       return &t;
     }
 
-    level3 ([&]{trace << "no existing file found for prerequisite " << pk;});
+    level4 ([&]{trace << "no existing file found for prerequisite " << pk;});
     return nullptr;
   }
 
@@ -164,7 +164,7 @@ namespace build
 
     target& t (r.first);
 
-    level4 ([&]{trace << "new target " << t << " for prerequisite " << pk;});
+    level5 ([&]{trace << "new target " << t << " for prerequisite " << pk;});
 
     return t;
   }
diff --git a/build/target.cxx b/build/target.cxx
index 9e0bea7..9b20273 100644
--- a/build/target.cxx
+++ b/build/target.cxx
@@ -219,7 +219,7 @@ namespace build
       const string* ext (*k.ext);
       if (t.ext != ext)
       {
-        level4 ([&]{
+        level5 ([&]{
             diag_record r (trace);
             r << "assuming target " << t << " is the same as the one with ";
             if (ext == nullptr)
diff --git a/build/test/module.cxx b/build/test/module.cxx
index b3378ba..deda6e9 100644
--- a/build/test/module.cxx
+++ b/build/test/module.cxx
@@ -40,7 +40,7 @@ namespace build
       }
 
       const dir_path& out_root (r.out_path ());
-      level4 ([&]{trace << "for " << out_root;});
+      level5 ([&]{trace << "for " << out_root;});
 
       // Register the test operation.
       //
diff --git a/build/test/rule.cxx b/build/test/rule.cxx
index 25baaa7..ea268a9 100644
--- a/build/test/rule.cxx
+++ b/build/test/rule.cxx
@@ -416,9 +416,9 @@ namespace build
 
       args.push_back (nullptr); // Second.
 
-      if (verb)
+      if (verb >= 2)
         print_process (args);
-      else
+      else if (verb)
         text << "test " << t;
 
       {