WasmVM: long double precision missing in WASM (strtold, wcstold, printf %Lf) #38
Description
Summary
WASM uses 64-bit IEEE 754 doubles for both double and long double — there is no 80-bit extended precision. This causes strtold(), wcstold(), and printf with %Lf format specifier to produce incorrect results compared to native x86-64 which has 80-bit long double.
Affected os-test cases
basic/stdlib/strtoldbasic/wchar/wcstoldstdio/printf-Lf-width-precision-pos-args
Expected behavior
Long double operations should produce correct results within the limitations of 64-bit double precision, or tests should document the precision difference.
Context
This is a fundamental WASM platform limitation — the wasm32 target maps long double to double (64-bit). Discovered via os-test POSIX conformance suite. Tracked in posix-exclusions.json as fail / patched-sysroot.