[vcpkg] add env var VCPKG_OVERLAY_TRIPLETS

docs/users/config-environment.md

@@ -46,6 +46,12 @@ the platform dependent PATH seperator (Windows `;` | others `:`)
 
 Example (Windows): `C:\custom-ports\boost;C:\custom-ports\sqlite3`
 
+#### VCPKG_OVERLAY_TRIPLETS
+
+This environment variable allows users to add directories to search for triplets.
+[Example: overlay triplets](../examples/overlay-triplets-linux-dynamic.md).
+List paths to overlays using the platform dependent PATH seperator (Windows `;`, others `:`) 
+
 #### VCPKG_FORCE_SYSTEM_BINARIES
 
 This environment variable, if set, suppresses the downloading of CMake and Ninja and forces the use of the system binaries.

toolsrc/include/vcpkg/base/strings.h

@@ -191,6 +191,8 @@ namespace vcpkg::Strings
 
     std::vector<std::string> split(StringView s, const char delimiter);
 
+    std::vector<std::string> split_paths(StringView s);
+
     const char* find_first_of(StringView searched, StringView candidates);
 
     std::vector<StringView> find_all_enclosed(StringView input, StringView left_delim, StringView right_delim);

toolsrc/include/vcpkg/vcpkgcmdarguments.h

@@ -134,6 +134,7 @@ namespace vcpkg
         constexpr static StringLiteral OVERLAY_PORTS_ENV = "VCPKG_OVERLAY_PORTS";
         constexpr static StringLiteral OVERLAY_PORTS_ARG = "overlay-ports";
         std::vector<std::string> overlay_ports;
+        constexpr static StringLiteral OVERLAY_TRIPLETS_ENV = "VCPKG_OVERLAY_TRIPLETS";
         constexpr static StringLiteral OVERLAY_TRIPLETS_ARG = "overlay-triplets";
         std::vector<std::string> overlay_triplets;
 

toolsrc/src/vcpkg/base/files.cpp

@@ -1174,13 +1174,8 @@ namespace vcpkg::Files
 
         virtual std::vector<fs::path> find_from_PATH(const std::string& name) const override
         {
-#if defined(_WIN32)
             static constexpr StringLiteral EXTS[] = {".cmd", ".exe", ".bat"};
-            auto paths = Strings::split(System::get_environment_variable("PATH").value_or_exit(VCPKG_LINE_INFO), ';');
-#else  // ^^^ defined(_WIN32) // !defined(_WIN32) vvv
-            static constexpr StringLiteral EXTS[] = {""};
-            auto paths = Strings::split(System::get_environment_variable("PATH").value_or_exit(VCPKG_LINE_INFO), ':');
-#endif // ^^^ !defined(_WIN32)
+            auto paths = Strings::split_paths(System::get_environment_variable("PATH").value_or_exit(VCPKG_LINE_INFO));
 
             std::vector<fs::path> ret;
             std::error_code ec;

toolsrc/src/vcpkg/base/strings.cpp

@@ -180,6 +180,15 @@ std::vector<std::string> Strings::split(StringView s, const char delimiter)
     }
 }
 
+std::vector<std::string> Strings::split_paths(StringView s)
+{
+#if defined(_WIN32)
+    return Strings::split(s, ';');
+#else // ^^^ defined(_WIN32) // !defined(_WIN32) vvv
+    return Strings::split(s, ':');
+#endif
+}
+
 const char* Strings::find_first_of(StringView input, StringView chars)
 {
     return std::find_first_of(input.begin(), input.end(), chars.begin(), chars.end());

toolsrc/src/vcpkg/vcpkgcmdarguments.cpp

@@ -614,6 +614,7 @@ namespace vcpkg
         table.format(opt(OVERLAY_PORTS_ARG, "=", "<path>"), "Specify directories to be used when searching for ports");
         table.format("", "(also: " + format_environment_variable("VCPKG_OVERLAY_PORTS") + ')');
         table.format(opt(OVERLAY_TRIPLETS_ARG, "=", "<path>"), "Specify directories containing triplets files");
+        table.format("", "(also: " + format_environment_variable("VCPKG_OVERLAY_TRIPLETS") + ')');
         table.format(opt(BINARY_SOURCES_ARG, "=", "<path>"),
                      "Add sources for binary caching. See 'vcpkg help binarycaching'");
         table.format(opt(DOWNLOADS_ROOT_DIR_ARG, "=", "<path>"), "Specify the downloads root directory");
@@ -652,15 +653,20 @@ namespace vcpkg
             const auto vcpkg_overlay_ports_env = System::get_environment_variable(OVERLAY_PORTS_ENV);
             if (const auto unpacked = vcpkg_overlay_ports_env.get())
             {
-#ifdef WIN32
-                auto overlays = Strings::split(*unpacked, ';');
-#else
-                auto overlays = Strings::split(*unpacked, ':');
-#endif
+                auto overlays = Strings::split_paths(*unpacked);
                 overlay_ports.insert(std::end(overlay_ports), std::begin(overlays), std::end(overlays));
             }
         }
 
+        {
+            const auto vcpkg_overlay_triplets_env = System::get_environment_variable(OVERLAY_TRIPLETS_ENV);
+            if (const auto unpacked = vcpkg_overlay_triplets_env.get())
+            {
+                auto triplets = Strings::split_paths(*unpacked);
+                overlay_triplets.insert(std::end(overlay_triplets), std::begin(triplets), std::end(triplets));
+            }
+        }
+
         if (!vcpkg_root_dir)
         {
             const auto vcpkg_root_env = System::get_environment_variable(VCPKG_ROOT_DIR_ENV);