maintenance: fixed msvc warnings about unreachable code (#3991)

Author: Klaim

libmamba/include/mamba/solver/solution.hpp

@@ -124,7 +124,10 @@ namespace mamba::solver
                     {
                         return &(a.what);
                     }
-                    return nullptr;
+                    else
+                    {
+                        return nullptr;
+                    }
                 },
                 action
             );
@@ -171,7 +174,10 @@ namespace mamba::solver
                     {
                         return &(a.what);
                     }
-                    return nullptr;
+                    else
+                    {
+                        return nullptr;
+                    }
                 },
                 action
             );
@@ -214,7 +220,10 @@ namespace mamba::solver
                     {
                         return &(a.what);
                     }
-                    return nullptr;
+                    else
+                    {
+                        return nullptr;
+                    }
                 },
                 action
             );

libmamba/src/core/run.cpp

@@ -197,7 +197,7 @@ namespace mamba
         const Context& context,
         const std::string& name,
         const std::vector<std::string>& command,
-        LockFile proc_dir_lock
+        LockFile proc_dir_lock [[maybe_unused]]
     )
         : location{ proc_dir() / fmt::format("{}.json", getpid()) }
     {
@@ -302,9 +302,9 @@ namespace mamba
         const std::string& cwd,
         int stream_options,
         bool clean_env,
-        bool detach,
+        bool detach [[maybe_unused]],
         const std::vector<std::string>& env_vars,
-        const std::string& specific_process_name
+        const std::string& specific_process_name [[maybe_unused]]
     )
     {
         if (!fs::exists(prefix))

libmamba/src/core/util_os.cpp

@@ -494,7 +494,7 @@ namespace mamba
 #else
 
         CONSOLE_SCREEN_BUFFER_INFO coninfo;
-        auto res = GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
+        auto res [[maybe_unused]] = GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
         return coninfo.dwSize.X;
 #endif
     }
@@ -508,7 +508,7 @@ namespace mamba
 #else
 
         CONSOLE_SCREEN_BUFFER_INFO coninfo;
-        auto res = GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
+        auto res [[maybe_unused]] = GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
         return coninfo.srWindow.Bottom - coninfo.srWindow.Top + 1;
 #endif
     }

libmamba/src/solver/libsolv/helpers.cpp

@@ -1647,17 +1647,17 @@ namespace mamba::solver::libsolv
                 );
                 return {};
             }
-            if constexpr (std::is_same_v<Job, Request::Freeze>)
+            else if constexpr (std::is_same_v<Job, Request::Freeze>)
             {
                 return pool_add_matchspec(pool, job.spec, parser)
                     .transform([&](auto id) { raw_jobs.push_back(SOLVER_LOCK, id); });
             }
-            if constexpr (std::is_same_v<Job, Request::Keep>)
+            else if constexpr (std::is_same_v<Job, Request::Keep>)
             {
                 return pool_add_matchspec(pool, job.spec, parser)
                     .transform([&](auto id) { raw_jobs.push_back(SOLVER_USERINSTALLED, id); });
             }
-            if constexpr (std::is_same_v<Job, Request::Pin>)
+            else if constexpr (std::is_same_v<Job, Request::Pin>)
             {
                 // WARNING pins are not working with namespace dependencies so far
                 return pool_add_pin(pool, job.spec, MatchSpecParser::Libsolv)
@@ -1674,8 +1674,11 @@ namespace mamba::solver::libsolv
                         }
                     );
             }
-            assert(false);
-            return {};
+            else
+            {
+                assert(false);  // TODO c++23: replace by `std::unreachable();`
+                return {};
+            }
         }
     }
 
@@ -1698,7 +1701,10 @@ namespace mamba::solver::libsolv
                     {
                         return add_job(job, solv_jobs, pool, force_reinstall, parser);
                     }
-                    return {};
+                    else
+                    {
+                        return {};
+                    }
                 },
                 unknown_job
             );
@@ -1719,7 +1725,10 @@ namespace mamba::solver::libsolv
                     {
                         return add_job(job, solv_jobs, pool, force_reinstall, parser);
                     }
-                    return {};
+                    else
+                    {
+                        return {};
+                    }
                 },
                 unknown_job
             );

libmamba/src/util/environment.cpp

@@ -195,7 +195,7 @@ namespace mamba::util
         return util::get_windows_known_user_folder(WindowsKnowUserFolder::LocalAppData);
     }
 
-    auto which_system(std::string_view exe) -> fs::u8path
+    auto which_system(std::string_view /*exe*/) -> fs::u8path
     {
         return "";
     }

libmamba/src/util/url_manip.cpp

@@ -106,12 +106,19 @@ namespace mamba::util
         // when followed with a drive letter
         // to make it compatible with libcurl on unix
         auto [is_file_scheme, slashes, rest] = check_file_scheme_and_slashes(uri);
-        if (!on_win && is_file_scheme && path_has_drive_letter(rest)
-            && ((slashes.size() == 2) || (slashes.size() == 3)))
+        if constexpr (!on_win)
         {
-            return util::concat("file:////", rest);
+            if (is_file_scheme && path_has_drive_letter(rest)
+                && ((slashes.size() == 2) || (slashes.size() == 3)))
+            {
+                return util::concat("file:////", rest);
+            }
+            return uri;
+        }
+        else
+        {
+            return uri;
         }
-        return uri;
     }
 
     auto file_uri_unc2_to_unc4(std::string_view uri) -> std::string