Don't emit the 'vs prompt' warning when targeting arm64ec from an arm…

…64 developer command prompt.

Partial response to microsoft/vcpkg#40158

src/vcpkg/commands.install.cpp

@@ -1306,20 +1306,19 @@ namespace vcpkg
 #if defined(_WIN32)
         const auto maybe_common_triplet = Util::common_projection(
             action_plan.install_actions, [](const InstallPlanAction& to_install) { return to_install.spec.triplet(); });
-        if (maybe_common_triplet)
+        if (auto common_triplet = maybe_common_triplet.get())
         {
-            const auto& common_triplet = maybe_common_triplet.value_or_exit(VCPKG_LINE_INFO);
-            const auto maybe_common_arch = common_triplet.guess_architecture();
-            if (maybe_common_arch)
+            const auto maybe_common_arch = common_triplet->guess_architecture();
+            if (auto common_arch = maybe_common_arch.get())
             {
                 const auto maybe_vs_prompt = guess_visual_studio_prompt_target_architecture();
-                if (maybe_vs_prompt)
+                if (auto vs_prompt = maybe_vs_prompt.get())
                 {
-                    const auto common_arch = maybe_common_arch.value_or_exit(VCPKG_LINE_INFO);
-                    const auto vs_prompt = maybe_vs_prompt.value_or_exit(VCPKG_LINE_INFO);
-                    if (common_arch != vs_prompt)
+                    if (*common_arch != *vs_prompt &&
+                        !(*common_arch == CPUArchitecture::ARM64EC && *vs_prompt == CPUArchitecture::ARM64))
                     {
-                        msg::println_warning(msgVcpkgInVsPrompt, msg::value = vs_prompt, msg::triplet = common_triplet);
+                        msg::println_warning(
+                            msgVcpkgInVsPrompt, msg::value = *vs_prompt, msg::triplet = common_triplet);
                     }
                 }
             }