From 653c58bc41624ab545edaffcb3acf047cd87244e Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 5 Jun 2019 13:05:03 +0200
Subject: Tweak generated header heuristics, add more diagnostics

---
 build2/algorithm.cxx       |  2 +-
 build2/cc/compile-rule.cxx | 38 +++++++++++++++++++++++++++++++++++++-
 build2/cli/init.cxx        |  2 +-
 3 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/build2/algorithm.cxx b/build2/algorithm.cxx
index 0b7697d..892767a 100644
--- a/build2/algorithm.cxx
+++ b/build2/algorithm.cxx
@@ -378,7 +378,7 @@ namespace build2
       dr << fail << "no rule to " << diag_do (a, t);
 
       if (verb < 4)
-        dr << info << "re-run with --verbose 4 for more information";
+        dr << info << "re-run with --verbose=4 for more information";
     }
 
     return nullptr;
diff --git a/build2/cc/compile-rule.cxx b/build2/cc/compile-rule.cxx
index f30ea3b..d2ed278 100644
--- a/build2/cc/compile-rule.cxx
+++ b/build2/cc/compile-rule.cxx
@@ -1392,6 +1392,26 @@ namespace build2
             }
           };
 
+#if 1
+          // Enter all outer prefixes, including prefixless.
+          //
+          // The prefixless part is fuzzy but seems to be doing the right
+          // thing ignoring/overriding-wise, at least in cases where one of
+          // the competing -I paths is a subdirectory of another. But the
+          // proper solution will be to keep all the prefixless entries (by
+          // changing prefix_map to a multimap) since for them we have an
+          // extra checks (target must be explicitly spelled out in a
+          // buildfile).
+          //
+          for (size_t prio (0);; ++prio)
+          {
+            bool e (p.empty ());
+            enter ((e ? move (p) : p), (e ? move (d) : d), prio);
+            if (e)
+              break;
+            p = p.directory ();
+          }
+#else
           size_t prio (0);
           for (bool e (false); !e; ++prio)
           {
@@ -1400,6 +1420,7 @@ namespace build2
             enter ((e ? move (p) : p), (e ? move (d) : d), prio);
             p = move (n);
           }
+#endif
         }
       }
     }
@@ -2302,6 +2323,8 @@ namespace build2
             {
               const dir_path& pd (i->second.directory);
 
+              l4 ([&]{trace << "prefix '" << d << "' mapped to " << pd;});
+
               // If this is a prefixless mapping, then only use it if we can
               // resolve it to an existing target (i.e., it is explicitly
               // spelled out in a buildfile).
@@ -2315,8 +2338,14 @@ namespace build2
                 f = pd / f;
                 l4 ([&]{trace << "mapped as auto-generated " << f;});
               }
+              else
+                l4 ([&]{trace << "no explicit target in " << pd;});
             }
+            else
+              l4 ([&]{trace << "no prefix map entry for '" << d << "'";});
           }
+          else
+            l4 ([&]{trace << "prefix map is empty";});
         }
       }
       else
@@ -3150,7 +3179,14 @@ namespace build2
                                       move (hp), cache,
                                       pfx_map, so_map).first);
         if (ht == nullptr)
-          fail << "header '" << hp << "' not found and cannot be generated";
+        {
+          diag_record dr;
+          dr << fail << "header '" << hp
+             << "' not found and cannot be generated";
+
+          if (verb < 4)
+            dr << info << "re-run with --verbose=4 for more information";
+        }
 
         if (optional<bool> u = inject_header (a, t, *ht, cache, mt))
         {
diff --git a/build2/cli/init.cxx b/build2/cli/init.cxx
index 0efea9a..acbbb33 100644
--- a/build2/cli/init.cxx
+++ b/build2/cli/init.cxx
@@ -327,7 +327,7 @@ namespace build2
       {
         if (!optional)
           fail (l) << "cli module could not be configured" <<
-            info << "re-run with -V option for more information";
+            info << "re-run with -V for more information";
 
         return false;
       }
-- 
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