Description

A compilation error occurs in onWayland() function when building Wails v2.10.2 on some compilers.
The function declares a variable inside a case block without braces, which is not allowed in standard C.

Error message:

window.c:79:6: error: a label can only be part of a statement and a declaration is not a statement
   79 |      char *gdkBackend = getenv("XDG_SESSION_TYPE");
      |      ^~~~

To Reproduce

Steps to reproduce the behaviour:

Build the project for Linux target:

wails build -platform linux/amd64

Compilation fails with the above error.

Expected behaviour

The code should compile successfully on any standard-compliant C compiler, even those that strictly enforce C rules.
Specifically, variables should not be declared directly inside a case label without a new scope or outside the switch statement.

Screenshots

N/A — this is a compiler error and does not produce a UI screen.
Relevant build log snippet:

window.c: In function ‘onWayland’:
window.c:79:6: error: a label can only be part of a statement and a declaration is not a statement
   79 |      char *gdkBackend = getenv("XDG_SESSION_TYPE");
      |      ^~~~
ERROR   exit status 1

Attempted Fixes

The root cause of the compilation error is that in C, declarations inside a case label must be inside a block scope (i.e., surrounded by {}), or be declared before the switch statement. This is because a case label is not a separate block by itself and declaring variables directly under it is not allowed by the C standard.

Original problematic code:

case -1:
    char *gdkBackend = getenv("XDG_SESSION_TYPE");
    if(gdkBackend != NULL && strcmp(gdkBackend, "wayland") == 0) 
    {
        wmIsWayland = 1;
        return TRUE;
    }

    wmIsWayland = 0;
    return FALSE;

Fix 1: Wrap in braces to create a new scope

case -1: {
    char *gdkBackend = getenv("XDG_SESSION_TYPE");
    if(gdkBackend != NULL && strcmp(gdkBackend, "wayland") == 0) 
    {
        wmIsWayland = 1;
        return TRUE;
    }

    wmIsWayland = 0;
    return FALSE;
}

Fix 2: Move declaration outside the switch (recommended for better clarity and compatibility)

char *gdkBackend = NULL;

switch (wmIsWayland)
{
case -1:
    gdkBackend = getenv("XDG_SESSION_TYPE");
    if(gdkBackend != NULL && strcmp(gdkBackend, "wayland") == 0) 
    {
        wmIsWayland = 1;
        return TRUE;
    }

    wmIsWayland = 0;
    return FALSE;

Both fixes solve the compilation error by respecting C language rules on declarations within switch-case statements.

System Details

GOVERSION: go1.23.4 linux/amd64

Additional context

The problematic file is v2/internal/frontend/desktop/linux/window.c

The error occurs during the Linux build step of wails build.

Likely to affect any environment where the C compiler enforces standard C rules (e.g., -std=c89 or -std=c99 without extensions).

Proposed fix: move char *gdkBackend declaration out of the case block or wrap it in braces.