Add support for dynamic dependencies in ad hoc Buildscript recipes

Specifically, add the new `depdb dyndep` builtin that can be used to extract
dynamic dependencies from a program run or a file. For example:

obje{hello.o}: cxx{hello}
{{
  s = $path($<[0])

  depdb dyndep $cxx.poptions $cc.poptions --what=header --default-prereq-type=h -- $cxx.path $cxx.poptions $cc.poptions $cxx.mode -M -MG $s

  diag c++ ($<[0])

  o = $path($>)
  $cxx.path $cxx.poptions $cc.poptions $cc.coptions $cxx.coptions $cxx.mode -o $o -c $s
}}

Currently only the `make` dependency format is supported.

1 files changed, 49 insertions, 30 deletions

diff --git a/libbuild2/buildfile b/libbuild2/buildfile
index 17003b5..f21be7b 100644
--- a/libbuild2/buildfile
+++ b/libbuild2/buildfile
@@ -32,7 +32,8 @@ lib{build2}: libul{build2}:                                            \
 libul{build2}: script/{hxx ixx txx cxx}{** -*-options -**.test...} \
                script/{hxx ixx cxx}{builtin-options}
 
-libul{build2}: build/{hxx ixx txx cxx}{** -**.test...}
+libul{build2}: build/script/{hxx ixx txx cxx}{** -*-options -**.test...} \
+               build/script/{hxx ixx cxx}{builtin-options}
 
 # Note that this won't work in libul{} since it's not installed.
 #
@@ -216,38 +217,56 @@ else
 
 # Generated options parser.
 #
-script/
+# @@ Consider generating common cli runtime namespace if adding more option
+#    files. Plus sommon types-parser.?xx (which could also potentially be
+#    reused by the driver).
+#
+if $cli.configured
 {
-  if $cli.configured
+  cli.options += --std c++11 -I $src_root --include-with-brackets \
+--generate-vector-scanner --generate-modifier --generate-specifier \
+--suppress-usage
+
+  cli.cxx{*}:
   {
-    cli.cxx{builtin-options}: cli{builtin}
-
-    cli.options += --std c++11 -I $src_root --include-with-brackets \
---include-prefix libbuild2/script --guard-prefix LIBBUILD2_SCRIPT \
---cli-namespace build2::script::cli --generate-vector-scanner \
---generate-modifier --generate-specifier --suppress-usage
-
-    cli.cxx{*}:
-    {
-      # Include the generated cli files into the distribution and don't remove
-      # them when cleaning in src (so that clean results in a state identical
-      # to distributed). But don't install their headers since they are only
-      # used internally in the testscript implementation.
-      #
-      dist  = true
-      clean = ($src_root != $out_root)
-      install = false
-
-      # We keep the generated code in the repository so copy it back to src in
-      # case of a forwarded configuration.
-      #
-      backlink = overwrite
-    }
-  }
-  else
-    # No install for the pre-generated case.
+    # Include the generated cli files into the distribution and don't remove
+    # them when cleaning in src (so that clean results in a state identical
+    # to distributed). But don't install their headers since they are only
+    # used internally in the testscript implementation.
+    #
+    dist  = true
+    clean = ($src_root != $out_root)
+    install = false
+
+    # We keep the generated code in the repository so copy it back to src in
+    # case of a forwarded configuration.
     #
-    hxx{builtin-options}@./ ixx{builtin-options}@./: install = false
+    backlink = overwrite
+  }
+
+  script/cli.cxx{builtin-options}: script/cli{builtin}
+  {
+    cli.options += --cli-namespace build2::script::cli \
+--include-prefix libbuild2/script --guard-prefix LIBBUILD2_SCRIPT
+  }
+
+  build/script/cli.cxx{builtin-options}: build/script/cli{builtin}
+  {
+    cli.options += --cli-namespace build2::build::script::cli \
+--include-prefix libbuild2/build/script --guard-prefix LIBBUILD2_BUILD_SCRIPT \
+--cxx-prologue "#include <libbuild2/build/script/types-parsers.hxx>" \
+--generate-parse
+  }
+}
+else
+{
+  # No install for the pre-generated case.
+  #
+  script/hxx{builtin-options}@./ \
+  script/ixx{builtin-options}@./: install = false
+
+  build/script/hxx{builtin-options}@./ \
+  build/script/ixx{builtin-options}@./: install = false
 }
 
 # Install into the libbuild2/ subdirectory of, say, /usr/include/