diff options
Diffstat (limited to 'libbuild2/cc')
| -rw-r--r-- | libbuild2/cc/link-rule.cxx | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/libbuild2/cc/link-rule.cxx b/libbuild2/cc/link-rule.cxx index 50c56a4..2e644cc 100644 --- a/libbuild2/cc/link-rule.cxx +++ b/libbuild2/cc/link-rule.cxx @@ -2470,14 +2470,33 @@ namespace build2 // Note that execute_prerequisites() blanks out all the ad hoc // prerequisites so we don't need to worry about them from now on. // + // There is an interesting trade-off between the straight and reverse + // execution. With straight we may end up with inaccurate progress if + // most of our library prerequisites (typically specified last) are + // already up to date. In this case, the progress will first increase + // slowly as we compile this target's source files and then jump + // straight to 100% as we "realize" that all the libraries (and all + // their prerequisites) are already up to date. + // + // Switching to reverse fixes this but messes up incremental building: + // now instead of starting to compile source files right away, we will + // first spend some time making sure all the libraries are up to date + // (which, in case of an error in the source code, will be a complete + // waste). + // + // There doesn't seem to be an easy way to distinguish between + // incremental and from-scratch builds and on balance fast incremental + // builds feel more important. + // target_state ts; - if (optional<target_state> s = - execute_prerequisites (a, - t, - mt, - [] (const target&, size_t) {return false;})) + if (optional<target_state> s = execute_prerequisites ( + a, t, + mt, + [] (const target&, size_t) {return false;})) + { ts = *s; + } else { // An ad hoc prerequisite renders us out-of-date. Let's update from |