feat: add a linker_script attribute to the Zig build rules

.bazelrc

@@ -7,8 +7,8 @@ import %workspace%/.bazelrc.flags
 # Deleted packages for integration tests.
 # To update these lines, execute
 # `bazel run @contrib_rules_bazel_integration_test//tools:update_deleted_packages`
-build --deleted_packages=e2e/workspace,e2e/workspace/configure-mode,e2e/workspace/configure-threaded,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace
-query --deleted_packages=e2e/workspace,e2e/workspace/configure-mode,e2e/workspace/configure-threaded,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace
+build --deleted_packages=e2e/workspace,e2e/workspace/configure-mode,e2e/workspace/configure-threaded,e2e/workspace/linker-script,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace
+query --deleted_packages=e2e/workspace,e2e/workspace/configure-mode,e2e/workspace/configure-threaded,e2e/workspace/linker-script,e2e/workspace/multiple-sources-and-packages-test,e2e/workspace/multiple-sources-binary,e2e/workspace/simple-binary,e2e/workspace/simple-library,e2e/workspace/simple-test,e2e/workspace/transitive-zig-packages-binary,e2e/workspace/transitive-zig-packages-binary/hello-world,e2e/workspace/transitive-zig-packages-binary/hello-world/data,e2e/workspace/transitive-zig-packages-binary/hello-world/data/hello,e2e/workspace/transitive-zig-packages-binary/hello-world/data/world,e2e/workspace/transitive-zig-packages-binary/hello-world/io,e2e/workspace/zig-package-binary,e2e/workspace/zig-package-binary/data,e2e/workspace/zig-package-binary/io,zig/tests/integration_tests/workspace
 
 # Load any settings specific to the current user.
 # .bazelrc.user should appear in .gitignore so that settings are not shared with team members

e2e/workspace/linker-script/BUILD.bazel

@@ -0,0 +1,41 @@
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
+load("@bazel_skylib//rules:diff_test.bzl", "diff_test")
+load("@rules_zig//zig:defs.bzl", "zig_binary", "zig_library", "zig_test")
+
+zig_binary(
+    name = "binary",
+    linker_script = "custom.ld",
+    main = "bin.zig",
+)
+
+genrule(
+    name = "bin_output",
+    outs = ["bin_output.actual"],
+    cmd = "$(execpath :binary) > $(OUTS)",
+    tools = [":binary"],
+)
+
+diff_test(
+    name = "bin_output_test",
+    file1 = ":bin_output.expected",
+    file2 = ":bin_output.actual",
+)
+
+zig_library(
+    name = "library",
+    linker_script = "custom.ld",
+    main = "lib.zig",
+)
+
+build_test(
+    name = "library_build_test",
+    targets = [
+        ":library",
+    ],
+)
+
+zig_test(
+    name = "test",
+    linker_script = "custom.ld",
+    main = "test.zig",
+)

e2e/workspace/linker-script/bin.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+extern const custom_global_symbol: u8;
+
+pub fn main() !void {
+    try std.io.getStdOut().writer().print("{d}\n", .{custom_global_symbol});
+}

e2e/workspace/linker-script/bin_output.expected

@@ -0,0 +1 @@
+42

e2e/workspace/linker-script/custom.ld

@@ -0,0 +1,21 @@
+SECTIONS
+{
+  . = 0x200000 + SIZEOF_HEADERS;
+  .rodata : { *(.rodata*) }
+  . += 0x10000;
+  .text : { *(.text*) }
+  . += 0x10000;
+  .got : { *(.got*) }
+  . += 0x10000;
+  .bss : { *(.bss*) }
+  . += 0x10000 - SIZEOF(.bss) % 0x10000;
+  .tbss : { *(.tbss*) }
+  . += 0x10000 - SIZEOF(.tbss) % 0x10000;
+  .data : { *(.data*) }
+  . += 0x10000;
+  .custom ALIGN(0x8) :
+  {
+    PROVIDE(custom_global_symbol = .);
+    BYTE(42)
+  }
+}

e2e/workspace/linker-script/lib.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+extern const custom_global_symbol: u8;
+
+export fn getCustomGlobalSymbol() u8 {
+    return custom_global_symbol;
+}

e2e/workspace/linker-script/test.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+extern const custom_global_symbol: u8;
+
+test "custom_global_symbol is 42" {
+    try std.testing.expectEqual(@as(u8, 42), custom_global_symbol);
+}

zig/private/BUILD.bazel

@@ -30,31 +30,33 @@ bzl_library(
     visibility = ["//zig:__subpackages__"],
     deps = [
         "//zig/private/common:filetypes",
+        "//zig/private/common:linker_script",
         "//zig/private/common:zig_cache",
         "//zig/private/providers:zig_package_info",
         "//zig/private/providers:zig_settings_info",
     ],
 )
 
 bzl_library(
-    name = "zig_library",
-    srcs = ["zig_library.bzl"],
+    name = "zig_configure",
+    srcs = ["zig_configure.bzl"],
     visibility = ["//zig:__subpackages__"],
     deps = [
-        "//zig/private/common:filetypes",
-        "//zig/private/common:zig_cache",
-        "//zig/private/providers:zig_package_info",
-        "//zig/private/providers:zig_settings_info",
+        ":settings",
+        "@bazel_skylib//lib:paths",
     ],
 )
 
 bzl_library(
-    name = "zig_configure",
-    srcs = ["zig_configure.bzl"],
+    name = "zig_library",
+    srcs = ["zig_library.bzl"],
     visibility = ["//zig:__subpackages__"],
     deps = [
-        ":settings",
-        "@bazel_skylib//lib:paths",
+        "//zig/private/common:filetypes",
+        "//zig/private/common:linker_script",
+        "//zig/private/common:zig_cache",
+        "//zig/private/providers:zig_package_info",
+        "//zig/private/providers:zig_settings_info",
     ],
 )
 

zig/private/common/BUILD.bazel

@@ -13,12 +13,19 @@ bzl_library(
     visibility = ["//zig:__subpackages__"],
 )
 
+bzl_library(
+    name = "linker_script",
+    srcs = ["linker_script.bzl"],
+    visibility = ["//zig:__subpackages__"],
+)
+
 # Execute `bazel run //util:update_filegroups` to update this target.
 filegroup(
     name = "all_files",
     srcs = [
         ":BUILD.bazel",
         ":filetypes.bzl",
+        ":linker_script.bzl",
         ":zig_cache.bzl",
     ],
     visibility = ["//zig/private:__pkg__"],

zig/private/common/linker_script.bzl

@@ -0,0 +1,19 @@
+"""Handle custom linker scripts."""
+
+def zig_linker_script(*, linker_script, inputs, args):
+    """Handle custom linker scripts.
+
+    Sets the appropriate command-line flags for the Zig compiler to configure a
+    custom linker script, if provided.
+
+    Args:
+      linker_script: optional; Label, The linker script attribute.
+      inputs: List; mutable, Append the linker script inputs to this collection.
+      args: Args; mutable, Append the Zig command-line flags to this object.
+    """
+
+    if linker_script == None:
+        return
+
+    inputs.append(linker_script)
+    args.add_all(["-T", linker_script])

zig/private/zig_binary.bzl

@@ -1,6 +1,7 @@
 """Implementation of the zig_binary rule."""
 
 load("//zig/private/common:filetypes.bzl", "ZIG_SOURCE_EXTENSIONS")
+load("//zig/private/common:linker_script.bzl", "zig_linker_script")
 load("//zig/private/common:zig_cache.bzl", "zig_cache_output")
 load(
     "//zig/private/providers:zig_package_info.bzl",
@@ -32,6 +33,11 @@ ATTRS = {
         mandatory = False,
         providers = [ZigPackageInfo],
     ),
+    "linker_script": attr.label(
+        doc = "Custom linker script for the target.",
+        allow_single_file = True,
+        mandatory = False,
+    ),
     "_settings": attr.label(
         default = "//zig/settings",
         doc = "Zig build settings.",
@@ -65,6 +71,12 @@ def _zig_binary_impl(ctx):
         args = args,
     )
 
+    zig_linker_script(
+        linker_script = ctx.file.linker_script,
+        inputs = direct_inputs,
+        args = args,
+    )
+
     zig_cache_output(
         actions = ctx.actions,
         name = ctx.label.name,

zig/private/zig_library.bzl

@@ -1,6 +1,7 @@
 """Implementation of the zig_library rule."""
 
 load("//zig/private/common:filetypes.bzl", "ZIG_SOURCE_EXTENSIONS")
+load("//zig/private/common:linker_script.bzl", "zig_linker_script")
 load("//zig/private/common:zig_cache.bzl", "zig_cache_output")
 load(
     "//zig/private/providers:zig_package_info.bzl",
@@ -32,6 +33,11 @@ ATTRS = {
         mandatory = False,
         providers = [ZigPackageInfo],
     ),
+    "linker_script": attr.label(
+        doc = "Custom linker script for the target.",
+        allow_single_file = True,
+        mandatory = False,
+    ),
     "_settings": attr.label(
         default = "//zig/settings",
         doc = "Zig build settings.",
@@ -66,6 +72,12 @@ def _zig_library_impl(ctx):
         args = args,
     )
 
+    zig_linker_script(
+        linker_script = ctx.file.linker_script,
+        inputs = direct_inputs,
+        args = args,
+    )
+
     zig_cache_output(
         actions = ctx.actions,
         name = ctx.label.name,

zig/private/zig_test.bzl

@@ -1,6 +1,7 @@
 """Implementation of the zig_test rule."""
 
 load("//zig/private/common:filetypes.bzl", "ZIG_SOURCE_EXTENSIONS")
+load("//zig/private/common:linker_script.bzl", "zig_linker_script")
 load("//zig/private/common:zig_cache.bzl", "zig_cache_output")
 load(
     "//zig/private/providers:zig_package_info.bzl",
@@ -32,6 +33,11 @@ ATTRS = {
         mandatory = False,
         providers = [ZigPackageInfo],
     ),
+    "linker_script": attr.label(
+        doc = "Custom linker script for the target.",
+        allow_single_file = True,
+        mandatory = False,
+    ),
     "_settings": attr.label(
         default = "//zig/settings",
         doc = "Zig build settings.",
@@ -65,6 +71,12 @@ def _zig_test_impl(ctx):
         args = args,
     )
 
+    zig_linker_script(
+        linker_script = ctx.file.linker_script,
+        inputs = direct_inputs,
+        args = args,
+    )
+
     zig_cache_output(
         actions = ctx.actions,
         name = ctx.label.name,