configure_make() and meson() don't work with hermetic toolchain

[mering]

See #1295 for a reproduction example.

Both configure() and meson() don't seem to detect the hermetic toolchain and fail with errors like C compiler cannot create executables.

[untimtam]

Relevant for meson: #1222

[filmil]

Seeing similar issues (apparently) at https://github.com/filmil/bazel_delib

[voxeljorge]

Not all configure based applications fail, I'm able to build some. FFmpeg is an unusual example because they've explicitly decided to ignore CC CFLAGS etc, which is how foreign_cc sets these parameters.

For meson I've found that my issue shows errors like this in the log:

Sanity check compile stderr:
ld.lld: error: cannot open Scrt1.o: No such file or directory
ld.lld: error: cannot open crti.o: No such file or directory
ld.lld: error: unable to find library -lm
ld.lld: error: unable to find library -lpthread
ld.lld: error: unable to find library -ldl
ld.lld: error: unable to find library -lc
ld.lld: error: cannot open crtn.o: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I have an llvm toolchain configured with a sysroot, and my best guess is that because my sysroot is being passed with a relative path (instead of absolute) meson commands fail to find it. Here's an example command:

/home/jorge/.cache/bazel/_bazel_jorge/576ee54cf2522471c5c073f98825487b/sandbox/linux-sandbox/22/execroot/_main/external/toolchains_llvm~~llvm~llvm_toolchain/bin/cc_wrapper.sh'
    sanitycheckc.c
    -o
    sanitycheckc.exe
    '--sysroot=/home/jorge/.cache/bazel/_bazel_jorge/576ee54cf2522471c5c073f98825487b/sandbox/linux-sandbox/22/execroot/_main/external/_main~_repo_rules~ubuntu_20_04_sysroot'
    -D_FILE_OFFSET_BITS=64
    -Wl,-S
    --target=x86_64-unknown-linux-gnu
    -lm
    -no-canonical-prefixes
    -fuse-ld=lld
    -Wl,--build-id=md5
    -Wl,--hash-style=gnu
    -Wl,-z,relro,-z,now
    -l:libc++.a
    -l:libc++abi.a
    -l:libunwind.a
    -lpthread
    -ldl
    -rtlib=compiler-rt
    '--sysroot=external/_main~_repo_rules~ubuntu_20_04_sysroot/

I tried hardcoding an absolute sysroot with a CFLAGS env but unfortunately the parameters are not ordered correctly and the relative one takes precedence.

[voxeljorge]

I can confirm that at least in my case the issue comes from having a relative sysroot, the following patch resolves my build issue:

diff --git a/foreign_cc/meson.bzl b/foreign_cc/meson.bzl
index 9d4179a..e39886a 100644
--- a/foreign_cc/meson.bzl
+++ b/foreign_cc/meson.bzl
@@ -54,6 +54,15 @@ def _meson_impl(ctx):
     )
     return cc_external_rule_impl(ctx, attrs)
 
+def _absolutize_sysroot_flag(workspace_name, flags):
+    fixed_flags = []
+    for flag in flags:
+        if not flag.startswith("--sysroot="):
+            fixed_flags.append(flag)
+            continue
+        fixed_flags.append("--sysroot="+_absolutize(workspace_name, flag.lstrip("--sysroot=")))
+    return fixed_flags
+
 def _create_meson_script(configureParameters):
     """Creates the bash commands for invoking commands to build meson projects
 
@@ -86,6 +95,9 @@ def _create_meson_script(configureParameters):
     copts = (ctx.fragments.cpp.copts + ctx.fragments.cpp.conlyopts + getattr(ctx.attr, "copts", [])) or []
     cxxopts = (ctx.fragments.cpp.copts + ctx.fragments.cpp.cxxopts + getattr(ctx.attr, "copts", [])) or []
 
+    copts = _absolutize_sysroot_flag(ctx.workspace_name, copts)
+    cxxopts = _absolutize_sysroot_flag(ctx.workspace_name, cxxopts)
+
     if copts:
         script.append("##export_var## CFLAGS \"{} ${{CFLAGS:-}}\"".format(" ".join(copts).replace("\"", "'")))
     if cxxopts:
@@ -93,7 +105,8 @@ def _create_meson_script(configureParameters):
 
     flags = get_flags_info(ctx)
     if flags.cxx_linker_executable:
-        script.append("##export_var## LDFLAGS \"{} ${{LDFLAGS:-}}\"".format(" ".join(flags.cxx_linker_executable).replace("\"", "'")))
+        ldflags = _absolutize_sysroot_flag(ctx.workspace_name, flags.cxx_linker_executable)
+        script.append("##export_var## LDFLAGS \"{} ${{LDFLAGS:-}}\"".format(" ".join(ldflags).replace("\"", "'")))
 
     script.append("##export_var## CMAKE {}".format(attrs.cmake_path))
     script.append("##export_var## NINJA {}".format(attrs.ninja_path))

[mering]

@voxeljorge I created #1303 to solve the issue with the relative sysroot similar to what is done for other foreign tools.

[voxeljorge]

@mering I can confirm that your PR fixes my build as well. I am not partial to the fix but I definitely would like to see one merged in