Prompt rebuild if external hash changes

toolsrc/include/vcpkg/binaryparagraph.h

@@ -7,6 +7,13 @@
 
 namespace vcpkg
 {
+    enum class ConsistencyState : unsigned
+    {
+        UNKNOWN = 0,
+        CONSISTENT,
+        INCONSISTENT,
+    };
+
     /// <summary>
     /// Built package metadata
     /// </summary>
@@ -23,6 +30,8 @@ namespace vcpkg
 
         std::string dir() const;
 
+        bool is_consistent() const;
+
         PackageSpec spec;
         std::string version;
         std::string description;
@@ -33,6 +42,8 @@ namespace vcpkg
         std::string abi;
         SourceParagraph::TYPE type;
         std::unordered_map<std::string, std::string> external_files;
+
+        mutable ConsistencyState consistency = ConsistencyState::UNKNOWN;
     };
 
     struct BinaryControlFile

toolsrc/src/vcpkg/binaryparagraph.cpp

@@ -1,6 +1,7 @@
 #include "pch.h"
 
 #include <vcpkg/base/checks.h>
+#include <vcpkg/base/hash.h>
 #include <vcpkg/base/system.print.h>
 #include <vcpkg/base/util.h>
 #include <vcpkg/binaryparagraph.h>
@@ -27,6 +28,32 @@ namespace vcpkg
         static const std::string EXTERNALFILES = "External-Files";
     }
 
+    bool BinaryParagraph::is_consistent() const
+    {
+        switch (consistency)
+        {
+        case ConsistencyState::UNKNOWN :
+            for (const auto& file_hash : external_files)
+            {
+                const auto& realfs = Files::get_real_filesystem();
+
+                if (realfs.is_regular_file(file_hash.first) &&
+                    Hash::get_file_hash(realfs, file_hash.first, "SHA1") != file_hash.second)
+                {
+                    consistency = ConsistencyState::INCONSISTENT;
+                    return false;
+                }
+            }
+
+            consistency = ConsistencyState::CONSISTENT;
+            return true;
+        case ConsistencyState::CONSISTENT : return true;
+        case ConsistencyState::INCONSISTENT : return false;
+        }
+
+        Checks::unreachable(VCPKG_LINE_INFO);
+    }
+
     BinaryParagraph::BinaryParagraph() = default;
 
     BinaryParagraph::BinaryParagraph(std::unordered_map<std::string, std::string> fields)

toolsrc/src/vcpkg/build.cpp

@@ -475,11 +475,15 @@ namespace vcpkg::Build
             {
                 hashes.emplace_back(external_file, it_hash->second);
             }
-            else if (fs.is_regular_file(external_file))
+            else if (Files::get_real_filesystem().is_regular_file(external_file))
             {
-                auto emp = s_hash_cache.emplace(external_file.u8string(),
+                auto emp = s_hash_cache.emplace(
-                                                Hash::get_file_hash(fs, external_file, "SHA1"));
+                        external_file.u8string(),
-                hashes.emplace_back(external_file, emp.first->second);
+                        Hash::get_file_hash(
+                            Files::get_real_filesystem(),
+                            external_file, "SHA1"));
+
+                hashes.emplace_back(external_file.u8string(), emp.first->second);
             }
             else
             {

toolsrc/src/vcpkg/dependencies.cpp

@@ -664,13 +664,17 @@ namespace vcpkg::Dependencies
 
         if (auto p_installed = cluster.installed.get())
         {
-            if (p_installed->original_features.find(feature) != p_installed->original_features.end())
+            if (p_installed->original_features.find(feature) != p_installed->original_features.end() &&
+                p_installed->ipv.core->package.is_consistent())
             {
                 return MarkPlusResult::SUCCESS;
             }
         }
 
-        // This feature was or will be uninstalled, therefore we need to rebuild
+        //The feature was not previously installed or the external files of the
+        //port are no longer consistent with the last installation of this port
+        //(they've either been modified or removed). Mark the cluster
+        //(aka the entire port) to be removed before re-adding it.
         mark_minus(cluster, graph, graph_plan, prevent_default_features);
 
         return follow_plus_dependencies(feature, cluster, graph, graph_plan, prevent_default_features);