C++26: A User-Friednly assert() macro

C++26 introduces a fix to the long-standing fragility of the assert() macro via proposal P2264R7. The core problem: assert() is a macro that uses the C preprocessor, which only understands parentheses for grouping — not template angle brackets or brace-initialization. This causes valid-looking assertions with templates, lambdas, or initializer lists to fail to compile unless wrapped in extra parentheses. The fix redefines assert as a variadic macro using __VA_ARGS__, making all previously broken patterns work without extra parentheses. The proposal also prevents accidental misuse of the comma operator (which would create always-true assertions), while still allowing diagnostic strings via the && operator. The change is backward-compatible and does not break existing code. As of early 2026, no major compiler supports this yet.