move --no-gc-sections hack to the toolchain definition

Thanks laurynasl for the tip.

toolchain/defs.bzl

@@ -78,33 +78,7 @@ fi
 export ZIG_LOCAL_CACHE_DIR="$_cache_prefix/bazel-zig-cc"
 export ZIG_GLOBAL_CACHE_DIR=$ZIG_LOCAL_CACHE_DIR
 
-lookup_args=()
-add_arg=
-case "{zig_tool}" in
-    cc|c++)
-        lookup_args=("-Wl,--gc-sections" "-Wl,--no-gc-sections")
-        add_arg="-Wl,--no-gc-sections"
-        ;;
-    ld.lld)
-        lookup_args=("--gc-sections" "--no-gc-sections")
-        add_arg="--no-gc-sections"
-        ;;
-esac
-
-has_special_arg=0
-for arg in "${{lookup_args[@]}}"; do
-    if [[ " ${{args[*]}} " == *" $arg "* ]]; then
-        has_special_arg=1
-        break
-    fi
-done
-
-args=( "$@" )
-if [[ "$has_special_arg" == 0 ]]; then
-    args+=( "$add_arg" )
-fi
-
-exec "{zig}" "{zig_tool}" "${{args[@]}}"
+exec "{zig}" "{zig_tool}" "$@"
 """
 
 _ZIG_TOOLS = [

toolchain/zig_toolchain.bzl

@@ -14,12 +14,15 @@ all_link_actions = [
     ACTION_NAMES.cpp_link_nodeps_dynamic_library,
 ]
 
-all_compile_actions = [
-    ACTION_NAMES.assemble,
+compile_and_link_actions = [
     ACTION_NAMES.c_compile,
+    ACTION_NAMES.cpp_compile,
+]
+
+rest_compile_actions = [
+    ACTION_NAMES.assemble,
     ACTION_NAMES.cc_flags_make_variable,
     ACTION_NAMES.clif_match,
-    ACTION_NAMES.cpp_compile,
     ACTION_NAMES.cpp_header_parsing,
     ACTION_NAMES.cpp_module_codegen,
     ACTION_NAMES.cpp_module_compile,
@@ -29,15 +32,7 @@ all_compile_actions = [
 ]
 
 def _zig_cc_toolchain_config_impl(ctx):
-    default_compiler_flags = feature(
-        name = "default_compiler_flags",
-        enabled = True,
-        flag_sets = [
-            flag_set(
-                actions = all_compile_actions,
-                flag_groups = [
-                    flag_group(
-                        flags = [
+    compiler_flags = [
         "-I" + d
         for d in ctx.attr.cxx_builtin_include_directories
     ] + [
@@ -48,9 +43,32 @@ def _zig_cc_toolchain_config_impl(ctx):
         "-D__DATE__=\"redacted\"",
         "-D__TIMESTAMP__=\"redacted\"",
         "-D__TIME__=\"redacted\"",
-                        ] + ctx.attr.copts,
+    ]
+    no_gc_sections = ["-Wl,--no-gc-sections"]
+
+    compile_and_link_flags = feature(
+        name = "compile_and_link_flags",
+        enabled = True,
+        flag_sets = [
+            flag_set(
+                actions = compile_and_link_actions,
+                flag_groups = [
+                    flag_group(flags = no_gc_sections),
+                    flag_group(flags = compiler_flags + ctx.attr.copts),
+                ],
             ),
         ],
+    )
+
+    rest_compile_flags = feature(
+        name = "rest_compile_flags",
+        enabled = True,
+        flag_sets = [
+            flag_set(
+                actions = rest_compile_actions,
+                flag_groups = [
+                    flag_group(flags = compiler_flags + ctx.attr.copts),
+                ],
             ),
         ],
     )
@@ -63,10 +81,9 @@ def _zig_cc_toolchain_config_impl(ctx):
                 actions = all_link_actions,
                 flag_groups = ([
                     flag_group(
-                        flags = [
-                            "-target",
-                            ctx.attr.target,
-                        ] + ctx.attr.linkopts,
+                        flags = ["-target", ctx.attr.target] +
+                                no_gc_sections +
+                                ctx.attr.linkopts,
                     ),
                 ]),
             ),
@@ -74,7 +91,8 @@ def _zig_cc_toolchain_config_impl(ctx):
     )
 
     features = [
-        default_compiler_flags,
+        compile_and_link_flags,
+        rest_compile_flags,
         default_linker_flags,
     ]