fixups regarding windows wide strings

* remove GetModuleHandleA from kernel32.zig. use of A functions
   considered harmful.
 * make it a compile error to expose WinMain instead of wWinMain. same
   thing.
 * start code declares wWinMainCRTStartup instead of WinMainCRTStartup
   when it has the choice.

lib/std/os/windows/kernel32.zig

@@ -112,8 +112,6 @@ pub extern "kernel32" fn GetFileAttributesW(lpFileName: [*]const WCHAR) callconv
 
 pub extern "kernel32" fn GetModuleFileNameW(hModule: ?HMODULE, lpFilename: [*]u16, nSize: DWORD) callconv(.Stdcall) DWORD;
 
-pub extern "kernel32" fn GetModuleHandleA(lpModuleName: ?LPCSTR) callconv(.Stdcall) ?HMODULE;
-
 pub extern "kernel32" fn GetModuleHandleW(lpModuleName: ?[*:0]const WCHAR) callconv(.Stdcall) ?HMODULE;
 
 pub extern "kernel32" fn GetLastError() callconv(.Stdcall) Win32Error;

lib/std/start.zig

@@ -29,11 +29,11 @@ comptime {
             if (!@hasDecl(root, "WinMain") and !@hasDecl(root, "WinMainCRTStartup") and
                 !@hasDecl(root, "wWinMain") and !@hasDecl(root, "wWinMainCRTStartup"))
             {
-                @export(WinStartup, .{ .name = "WinMainCRTStartup" });
+                @export(WinStartup, .{ .name = "wWinMainCRTStartup" });
             } else if (@hasDecl(root, "WinMain") and !@hasDecl(root, "WinMainCRTStartup") and
                 !@hasDecl(root, "wWinMain") and !@hasDecl(root, "wWinMainCRTStartup"))
             {
-                @export(WinMainCRTStartup, .{ .name = "WinMainCRTStartup" });
+                @compileError("WinMain not supported; declare wWinMain or main instead");
             } else if (@hasDecl(root, "wWinMain") and !@hasDecl(root, "wWinMainCRTStartup") and
                 !@hasDecl(root, "WinMain") and !@hasDecl(root, "WinMainCRTStartup"))
             {
@@ -162,18 +162,6 @@ fn WinStartup() callconv(.Stdcall) noreturn {
     std.os.windows.kernel32.ExitProcess(initEventLoopAndCallMain(u8, callMain));
 }
 
-fn WinMainCRTStartup() callconv(.Stdcall) noreturn {
-    @setAlignStack(16);
-    if (!builtin.single_threaded) {
-        _ = @import("start_windows_tls.zig");
-    }
-
-    std.debug.maybeEnableSegfaultHandler();
-
-    const result = initEventLoopAndCallMain(std.os.windows.INT, callWinMain);
-    std.os.windows.kernel32.ExitProcess(@bitCast(std.os.windows.UINT, result));
-}
-
 fn wWinMainCRTStartup() callconv(.Stdcall) noreturn {
     @setAlignStack(16);
     if (!builtin.single_threaded) {
@@ -182,7 +170,7 @@ fn wWinMainCRTStartup() callconv(.Stdcall) noreturn {
 
     std.debug.maybeEnableSegfaultHandler();
 
-    const result = initEventLoopAndCallMain(std.os.windows.INT, callWWinMain);
+    const result = initEventLoopAndCallMain(std.os.windows.INT, call_wWinMain);
     std.os.windows.kernel32.ExitProcess(@bitCast(std.os.windows.UINT, result));
 }
 
@@ -266,7 +254,7 @@ inline fn initEventLoopAndCallMain(comptime Out: type, comptime mainFunc: fn ()
 
             var result: u8 = undefined;
             var frame: @Frame(callMainAsync) = undefined;
-            _ = @asyncCall(&frame, &result, callMainAsync, .{u8, mainFunc, loop});
+            _ = @asyncCall(&frame, &result, callMainAsync, .{ u8, mainFunc, loop });
             loop.run();
             return result;
         }
@@ -323,24 +311,14 @@ pub fn callMain() u8 {
     }
 }
 
-pub fn callWinMain() std.os.windows.INT {
+pub fn call_wWinMain() std.os.windows.INT {
-    const hInstance = std.os.windows.kernel32.GetModuleHandleA(null);
+    const hInstance = @ptrCast(std.os.windows.HINSTANCE, std.os.windows.kernel32.GetModuleHandleW(null).?);
-    const lpCmdLine = std.os.windows.kernel32.GetCommandLineA();
+    const hPrevInstance: ?std.os.windows.HINSTANCE = null; // MSDN: "This parameter is always NULL"
-
-    // There's no (documented) way to get the nCmdShow parameter, so we're
-    // using this fairly standard default.
-    const nCmdShow = std.os.windows.user32.SW_SHOW;
-
-    return root.WinMain(hInstance, null, lpCmdLine, nCmdShow);
-}
-
-pub fn callWWinMain() std.os.windows.INT {
-    const hInstance = std.os.windows.kernel32.GetModuleHandleA(null);
     const lpCmdLine = std.os.windows.kernel32.GetCommandLineW();
 
     // There's no (documented) way to get the nCmdShow parameter, so we're
     // using this fairly standard default.
     const nCmdShow = std.os.windows.user32.SW_SHOW;
 
-    return root.wWinMain(hInstance, null, lpCmdLine, nCmdShow);
+    return root.wWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
 }

src/link/Coff.zig

@@ -1097,17 +1097,13 @@ fn linkWithLLD(self: *Coff, comp: *Compilation) !void {
                     try argv.append("-NODEFAULTLIB");
                     if (!is_lib) {
                         if (self.base.options.module) |module| {
-                            if (module.stage1_flags.have_winmain) {
+                            if (module.stage1_flags.have_winmain_crt_startup) {
-                                try argv.append("-ENTRY:WinMain");
-                            } else if (module.stage1_flags.have_wwinmain) {
-                                try argv.append("-ENTRY:wWinMain");
-                            } else if (module.stage1_flags.have_wwinmain_crt_startup) {
-                                try argv.append("-ENTRY:wWinMainCRTStartup");
-                            } else {
                                 try argv.append("-ENTRY:WinMainCRTStartup");
+                            } else {
+                                try argv.append("-ENTRY:wWinMainCRTStartup");
                             }
                         } else {
-                            try argv.append("-ENTRY:WinMainCRTStartup");
+                            try argv.append("-ENTRY:wWinMainCRTStartup");
                         }
                     }
                 }

test/stack_traces.zig

@@ -282,7 +282,7 @@ pub fn addCases(cases: *tests.StackTracesContext) void {
                     \\source.zig:10:8: [address] in main (test)
                     \\    foo();
                     \\       ^
-                    \\start.zig:301:29: [address] in std.start.posixCallMainAndExit (test)
+                    \\start.zig:289:29: [address] in std.start.posixCallMainAndExit (test)
                     \\            return root.main();
                     \\                            ^
                     \\start.zig:151:5: [address] in std.start._start (test)