[SV 63856] Fix pruning of double-colon rules

Given this setup:

  $ cat Makefile
  A::; @echo A-1 && sleep 1 && echo A-1 done
  A::; @echo A-2 && sleep 1 && echo A-2 done
  A::; @echo A-3 && sleep 1 && echo A-3 done
  B::; @echo B-1 && sleep 1 && echo B-1 done
  B::; @echo B-2 && sleep 1 && echo B-2 done
  B::; @echo B-3 && sleep 1 && echo B-3 done

  $ make -j8 A .WAIT B

All recipes for A should be started sequentially and complete before
any recipe for B is started, then all recipes for B should be started
sequentially.  This wasn't happening because the double-colon target
was getting pruned too early.

* src/remake.c (update_file): Don't prune a target if it's a double
colon rule which is complete, but there are other recipes to run for
this target: we want those other recipes to be run first.
* tests/scripts/targets/WAIT: Test .WAIT with double colon rules.

1 files changed, 8 insertions, 2 deletions

diff --git a/src/remake.c b/src/remake.c
index dec4667c..bdf78b3e 100644
--- a/src/remake.c
+++ b/src/remake.c
@@ -373,9 +373,15 @@ update_file (struct file *file, unsigned int depth)
     {
       /* Check for the case where a target has been tried and failed but
          the diagnostics haven't been issued. If we need the diagnostics
-         then we will have to continue. */
+         then we will have to continue.
+         In the case of double colon rules, this file cannot be pruned if
+         this recipe finished (file->command_state == cs_finished) and there
+         are more double colon rules for this file. Instead the recipe of the
+         next double colon rule of this file should be run.  */
       if (!(f->updated && f->update_status > us_none
-            && !f->dontcare && f->no_diag))
+            && !f->dontcare && f->no_diag)
+            && !(file->double_colon && file->command_state == cs_finished &&
+                 f->prev))
         {
           DBF (DB_VERBOSE, _("Pruning file '%s'.\n"));
           return f->command_state == cs_finished ? f->update_status : us_success;