Make build process consistent with non-build dependencies (#253)

* Return to spawning in a new process -- this is so its easier to
set the libs available to the dependency. There is probably a nice
way to do this with a temp $*REPO to avoid spawning a new process.

* No longer install build dependencies differently than other
dependencies -- this allows --dry --serial etc to continue being
useful.

Essentially we want each set of dependencies to have an isolated
environment, but installing build dependencies prior to anything
else means its much more difficult to get reproducibility between
run.

META6.json

@@ -31,7 +31,7 @@
         "Zef::Service::TAP"         : "lib/Zef/Service/TAP.pm6",
         "Zef::Service::P6CReporter" : "lib/Zef/Service/P6CReporter.pm6",
 
-        "Zef::Service::DistributionBuilder" : "lib/Zef/Service/DistributionBuilder.pm6",
+        "Zef::Service::Shell::DistributionBuilder" : "lib/Zef/Service/Shell/DistributionBuilder.pm6",
         "Zef::Service::Shell::LegacyBuild"  : "lib/Zef/Service/Shell/LegacyBuild.pm6",
         "Zef::Service::Shell::Test"         : "lib/Zef/Service/Shell/Test.pm6",
         "Zef::Service::Shell::prove"        : "lib/Zef/Service/Shell/prove.pm6",

lib/Zef/Client.pm6

@@ -1,7 +1,6 @@
 use Zef;
 use Zef::Distribution;
 use Zef::Distribution::Local;
-use Zef::Identity;
 use Zef::Repository;
 use Zef::Utils::FileSystem;
 
@@ -301,6 +300,7 @@ class Zef::Client {
     method build(*@candidates ($, *@)) {
         my @built = eager gather for @candidates -> $candi {
             my $dist := $candi.dist;
+
             unless $!builder.needs-build($dist) {
                 self.logger.emit({
                     level   => DEBUG,
@@ -504,17 +504,6 @@ class Zef::Client {
         die "Something went terribly wrong determining the build order" unless +@sorted-candidates;
 
 
-        for @sorted-candidates.grep: *.dist.builder -> $candi {
-            my $builder = "Distribution::Builder::$candi.dist.builder()";
-            try require ::($builder);
-            if $! {
-                my @builder-candidates = self.find-candidates(str2identity($builder));
-                @builder-candidates.append(self.find-prereq-candidates(|@builder-candidates));
-                self.install(:@to, |self.fetch(|@builder-candidates));
-            }
-        }
-
-
         # Setup(?) Phase:
         # Attach appropriate metadata so we can do --dry runs using -I/some/dep/path
         # and can install after we know they pass any required tests

lib/Zef/Distribution.pm6

@@ -73,8 +73,15 @@ class Zef::Distribution does Distribution is Zef::Distribution::DependencySpecif
         }
     }
     method build-depends-specs {
-        gather for $.build-depends.grep(*.defined) {
-            take Zef::Distribution::DependencySpecification.new(system-collapse($_));
+        gather {
+            for $.build-depends.grep(*.defined) {
+                take Zef::Distribution::DependencySpecification.new(system-collapse($_));
+            }
+
+            # XXX: Maybe the full namespace should be required? Otherwise makes it harder
+            # to handle :ver<> etc like everything else. It also requires external tools
+            # to have prior knowledge of this special build depends naming convention.
+            take Zef::Distribution::DependencySpecification.new("Distribution::Builder::{$.builder}") if $.builder
         }
     }
     method test-depends-specs  {

lib/Zef/Service/Shell/DistributionBuilder.pm6

@@ -0,0 +1,27 @@
+use Zef;
+
+class Zef::Service::Shell::DistributionBuilder does Builder does Messenger {
+    method build-matcher($dist) { ($dist.meta-version // 0) == 1 }
+    method needs-build($dist) { self.build-matcher($dist) and $dist.builder }
+
+    method probe { True }
+
+    method build($dist, :@includes) {
+        die "path does not exist: {$dist.path}" unless $dist.path.IO.e;
+
+        my $cmd  = "(require ::('Distribution::Builder::$dist.builder()')).new(meta => $dist.meta.perl()).build('$dist.path()') ?? exit(0) !! exit(1)";
+        my @exec = |($*EXECUTABLE, '-I.', |@includes.grep(*.defined).map({ "-I{$_}" }), '-e', "$cmd");
+
+        $.stdout.emit("Command: {@exec.join(' ')}");
+
+        my $ENV := %*ENV;
+        my $passed;
+        react {
+            my $proc = zrun-async(@exec);
+            whenever $proc.stdout.lines { $.stdout.emit($_) }
+            whenever $proc.stderr.lines { $.stderr.emit($_) }
+            whenever $proc.start(:$ENV, :cwd($dist.path)) { $passed = $_.so }
+        }
+        return $passed;
+    }
+}

resources/config.json

@@ -119,7 +119,7 @@
     "Build" : [
         {
             "short-name" : "default-builder",
-            "module" : "Zef::Service::DistributionBuilder"
+            "module" : "Zef::Service::Shell::DistributionBuilder"
         },
         {
             "short-name" : "legacy-builder",

t/00-load.t

@@ -31,7 +31,7 @@ subtest {
 subtest {
     use-ok("Zef::Service::FetchPath");
     use-ok("Zef::Service::TAP");
-    use-ok("Zef::Service::DistributionBuilder");
+    use-ok("Zef::Service::Shell::DistributionBuilder");
     use-ok("Zef::Service::Shell::LegacyBuild");
     use-ok("Zef::Service::Shell::Test");
     use-ok("Zef::Service::Shell::prove");