Ignore instead of overriding header prefix (now more specific -I's come first)

1 files changed, 10 insertions, 8 deletions

diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index 6fd6f16..2dc2a28 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -488,16 +488,18 @@ namespace build2
           {
             if (j->second != d)
             {
-              // We used to reject duplicates but it seems this can
-              // be reasonably expected to work according to the order
-              // of the -I options.
+              // We used to reject duplicates but it seems this can be
+              // reasonably expected to work according to the order of the -I
+              // options.
+              //
+              // Seeing that we normally have more "specific" -I paths first,
+              // (so that we don't pick up installed headers, etc), we ignore
+              // it.
               //
               if (verb >= 4)
-                trace << "overriding dependency prefix '" << p << "'\n"
-                      << "  old mapping to " << j->second << "\n"
-                      << "  new mapping to " << d;
-
-              j->second = d;
+                trace << "ignoring dependency prefix '" << p << "'\n"
+                      << "  existing mapping to " << j->second << "\n"
+                      << "  another mapping to  " << d;
             }
           }
           else