autoconf_linkopts

Resolve AC_SEARCH_LIBS / AC_SUBST results into linker flags at build time.

This rule reads the JSON result files from autoconf subst variables and produces a linker response file containing only the non-empty flags. The response file is returned via CcInfo so that cc_binary/cc_library targets can depend on it to get the correct platform-specific linkopts.

On GCC/Clang the flags are passed via a @response-file in user_link_flags. On MSVC/clang-cl (where nested @file is unsupported), a .c file with #pragma comment(lib, ...) directives is compiled and the resulting object is linked in, achieving the same effect through MSVC's native mechanism.

Example:

load("@rules_cc_autoconf//autoconf:autoconf_linkopts.bzl", "autoconf_linkopts")

autoconf_linkopts(
    name = "linkopts",
    vars = [
        "LIBPTHREAD",
        "FDATASYNC_LIB",
        "CLOCK_TIME_LIB",
    ],
    deps = [":autoconf"],
)

cc_binary(
    name = "my_binary",
    srcs = ["main.c"],
    deps = [":gnulib", ":linkopts"],
)

On modern Linux (glibc 2.34+) where pthread/rt functions are in libc, AC_SEARCH_LIBS produces empty values and no extra -l flags are added. On older systems, the appropriate flags (-lpthread, -lrt) are added automatically.

Rules

• autoconf_linkopts

autoconf_linkopts

load("@rules_cc_autoconf//autoconf:autoconf_linkopts.bzl", "autoconf_linkopts")

autoconf_linkopts(name, deps, defaults, vars)

Resolve AC_SEARCH_LIBS / AC_SUBST results into linker flags.

Reads subst result JSON files from autoconf deps and produces a linker response file. Returns CcInfo with the flags, so consumers can simply add this target to their deps list.

On GCC/Clang the flags are delivered via a @response-file. On MSVC/clang-cl a .c file with #pragma comment(lib, ...) directives is compiled instead, since MSVC's link.exe does not support nested response files.

Variables not found in the deps are silently ignored (they may be provided by a different module or not needed on this platform).

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