[vcpkg-make] default --prefix not passed to ./configure on fresh autotools builds → install lands under usr/local, vcpkg_fixup_pkgconfig fails (repro: jemalloc)

Summary

Under vcpkg baseline 56bb2411609227288b70117ead2c47585ba07713 (release 2026.04.27; host vcpkg-make ~2026-01-01), vcpkg_make_configure's default path/configure options — which carry --prefix=${CURRENT_INSTALLED_DIR} — do not reach the port's ./configure. Only a portfile's explicit OPTIONS pass through. With no --prefix, autotools configure defaults prefix=/usr/local, so make install DESTDIR=… lands files under <pkg>/usr/local; vcpkg_make_install's package-root rename (keyed on ${CURRENT_INSTALLED_DIR}) never fires; the .pc is stranded at usr/local/lib/pkgconfig; and vcpkg_fixup_pkgconfig aborts the build.

This is latent behind the binary cache — a pre-regression binary restores in milliseconds, so it only surfaces on a fresh build (cache eviction, baseline bump, or an overlay edit that re-keys the ABI).

Repro

• Triplet x64-linux, clean ubuntu:24.04, baseline 56bb2411, binary cache cleared (fresh build).
• Build an autotools port that relies on vcpkg_make_configure's default prefix propagation (observed with jemalloc 5.3.1).
• config.log shows ./configure invoked with no --prefix (e.g. only ./configure --enable-prof).
• Build fails at vcpkg_fixup_pkgconfig; the .pc is at …/usr/local/lib/pkgconfig/<port>.pc instead of …/lib/pkgconfig/.

Scope

Leans generic to vcpkg-make, not port-specific: the default-options function appends --prefix unconditionally (no per-port gate), and the drop is in the generic OPTIONS-assembly → configure path. A second fresh autotools-port build would settle it definitively. Possibly the same root cause as #50681 ([libb2] Build error on arm64-osx (pkg-config issue)).

Workaround (consumer side)

Pass the prefix + install-dir layout explicitly via per-config OPTIONS_RELEASE / OPTIONS_DEBUG (these do reach configure), mirroring vcpkg_make_common.cmake's own default-options block (RELEASE path_suffix "", DEBUG /debug). After that, config.log shows ./configure … --prefix=<CURRENT_INSTALLED_DIR> '--libdir=${prefix}/lib' … and the .pc lands correctly under lib/pkgconfig (release) / debug/lib/pkgconfig (debug).

Environment

• vcpkg baseline 56bb2411609227288b70117ead2c47585ba07713 (release 2026.04.27)
• x64-linux, ubuntu:24.04
• host vcpkg-make at the ~2026-01-01 revision

Start with the default-options block in vcpkg_make_common.cmake and trace how its OPTIONS are assembled before reaching ./configure. Reproduce a clean jemalloc build with the binary cache cleared, then inspect config.log and the installed .pc path. Done means the default --prefix and layout options reach configure and vcpkg_fixup_pkgconfig succeeds.