From b1398f09b4dedd19435460e02b49c42fa8bf7a1e Mon Sep 17 00:00:00 2001
From: Alexander Karatarakis <alkarata@microsoft.com>
Date: Fri, 23 Sep 2016 12:06:55 -0700
Subject: [PATCH] find_unment_dependencies() now works for a single package

---
 include/vcpkg_Dependencies.h  |  2 +-
 src/commands_installation.cpp | 11 ++++-------
 src/vcpkg_Dependencies.cpp    |  7 +++----
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/include/vcpkg_Dependencies.h b/include/vcpkg_Dependencies.h
index 94aa51f99..9dc32fc41 100644
--- a/include/vcpkg_Dependencies.h
+++ b/include/vcpkg_Dependencies.h
@@ -9,5 +9,5 @@ namespace vcpkg {namespace Dependencies
 {
     std::vector<package_spec> create_dependency_ordered_install_plan(const vcpkg_paths& paths, const std::vector<package_spec>& specs, const StatusParagraphs& status_db);
 
-    std::unordered_set<package_spec> find_unmet_dependencies(const vcpkg_paths& paths, const std::vector<package_spec>& specs, const StatusParagraphs& status_db);
+    std::unordered_set<package_spec> find_unmet_dependencies(const vcpkg_paths& paths, const package_spec& spec, const StatusParagraphs& status_db);
 }}
diff --git a/src/commands_installation.cpp b/src/commands_installation.cpp
index b688b8d5a..0902ba525 100644
--- a/src/commands_installation.cpp
+++ b/src/commands_installation.cpp
@@ -113,14 +113,14 @@ namespace vcpkg
 
     void build_command(const vcpkg_cmd_arguments& args, const vcpkg_paths& paths, const triplet& default_target_triplet)
     {
-        // Currently the code won't work for multiple packages if one of them depends on another.
+        // Installing multiple packages leads to unintuitive behavior if one of them depends on another.
         // Allowing only 1 package for now. 
         args.check_max_args(1);
 
         StatusParagraphs status_db = database_load_check(paths);
 
-        std::vector<package_spec> specs = args.parse_all_arguments_as_package_specs(default_target_triplet);
-        std::unordered_set<package_spec> unmet_dependencies = Dependencies::find_unmet_dependencies(paths, specs, status_db);
+        const package_spec spec = args.parse_all_arguments_as_package_specs(default_target_triplet).at(0);
+        std::unordered_set<package_spec> unmet_dependencies = Dependencies::find_unmet_dependencies(paths, spec, status_db);
         if (!unmet_dependencies.empty())
         {
             System::println(System::color::error, "The build command requires all dependencies to be already installed.");
@@ -135,10 +135,7 @@ namespace vcpkg
         }
 
         Environment::ensure_utilities_on_path(paths);
-        for (const package_spec& spec : specs)
-        {
-            build_internal(spec, paths);
-        }
+        build_internal(spec, paths);
         exit(EXIT_SUCCESS);
     }
 
diff --git a/src/vcpkg_Dependencies.cpp b/src/vcpkg_Dependencies.cpp
index 751b503c0..6ffb4959d 100644
--- a/src/vcpkg_Dependencies.cpp
+++ b/src/vcpkg_Dependencies.cpp
@@ -57,12 +57,11 @@ namespace vcpkg { namespace Dependencies
         return build_dependency_graph(paths, specs, status_db).find_topological_sort();
     }
 
-    std::unordered_set<package_spec> find_unmet_dependencies(const vcpkg_paths& paths, const std::vector<package_spec>& specs, const StatusParagraphs& status_db)
+    std::unordered_set<package_spec> find_unmet_dependencies(const vcpkg_paths& paths, const package_spec& spec, const StatusParagraphs& status_db)
     {
-        const Graphs::Graph<package_spec> dependency_graph = build_dependency_graph(paths, specs, status_db);
+        const Graphs::Graph<package_spec> dependency_graph = build_dependency_graph(paths, {spec}, status_db);
         std::unordered_set<package_spec> key_set = Maps::extract_key_set(dependency_graph.adjacency_list());
-        Sets::remove_all(&key_set, specs);
-
+        key_set.erase(spec);
         return key_set;
     }
 }}