From ef7d97a722260e0a4fbd110625355b556c7ab8e3 Mon Sep 17 00:00:00 2001
From: Hilton Chain <hako@ultrarare.space>
Date: Fri, 29 Nov 2024 14:13:30 +0800
Subject: [PATCH] Use system paths.

Prefer Guix search paths and support Guix cross builds.
---
 lib/std/zig/system.zig             | 25 +++++++++++---
 lib/std/zig/system/NativePaths.zig | 53 ++++++++++++++++++++++++++++++
 src/main.zig                       |  3 +-
 3 files changed, 76 insertions(+), 5 deletions(-)

diff --git a/lib/std/zig/system.zig b/lib/std/zig/system.zig
index 83c798c342..138d43f2e1 100644
--- a/lib/std/zig/system.zig
+++ b/lib/std/zig/system.zig
@@ -1123,10 +1123,27 @@ fn defaultAbiAndDynamicLinker(cpu: Target.Cpu, os: Target.Os, query: Target.Quer
         .os = os,
         .abi = abi,
         .ofmt = query.ofmt orelse Target.ObjectFormat.default(os.tag, cpu.arch),
-        .dynamic_linker = if (query.dynamic_linker.get() == null)
-            Target.DynamicLinker.standard(cpu, os.tag, abi)
-        else
-            query.dynamic_linker,
+        .dynamic_linker = if (query.dynamic_linker.get() == null) blk: {
+            var standard_linker = Target.DynamicLinker.standard(cpu, os.tag, abi);
+            if (standard_linker.get()) |standard_linker_path| {
+                if (builtin.os.tag != .windows and builtin.os.tag != .wasi) {
+                    if (posix.getenv("CROSS_LIBRARY_PATH") orelse posix.getenv("LIBRARY_PATH")) |library_path| {
+                        const linker_basename = fs.path.basename(standard_linker_path);
+                        var buffer: [255]u8 = undefined;
+                        var it = mem.tokenizeScalar(u8, library_path, ':');
+                        while (it.next()) |dir| {
+                            const linker_fullpath = std.fmt.bufPrint(&buffer, "{s}{s}{s}", .{ dir, fs.path.sep_str, linker_basename }) catch "";
+                            const guix_linker_path = fs.cwd().realpath(linker_fullpath, &buffer) catch "";
+                            if (guix_linker_path.len != 0) {
+                                standard_linker.set(guix_linker_path);
+                                break;
+                            }
+                        }
+                    }
+                }
+            }
+            break :blk standard_linker;
+        } else query.dynamic_linker,
     };
 }
 
diff --git a/lib/std/zig/system/NativePaths.zig b/lib/std/zig/system/NativePaths.zig
index 2a50e27b0c..f4cc0e8b3a 100644
--- a/lib/std/zig/system/NativePaths.zig
+++ b/lib/std/zig/system/NativePaths.zig
@@ -15,6 +15,51 @@ warnings: std.ArrayListUnmanaged([]const u8) = .{},
 
 pub fn detect(arena: Allocator, native_target: std.Target) !NativePaths {
     var self: NativePaths = .{ .arena = arena };
+    if (isGuix(arena)) {
+        inline for ([_][]const u8{ "CROSS_C_INCLUDE_PATH", "CROSS_CPLUS_INCLUDE_PATH" }) |env_var| {
+            if (process.getEnvVarOwned(arena, env_var)) |include_path| {
+                var it = mem.tokenizeScalar(u8, include_path, ':');
+                while (it.next()) |dir|
+                    try self.addIncludeDir(dir);
+            } else |err| switch (err) {
+                error.InvalidWtf8 => unreachable,
+                error.EnvironmentVariableNotFound => {},
+                error.OutOfMemory => |e| return e,
+            }
+        }
+        if (process.getEnvVarOwned(arena, "CROSS_LIBRARY_PATH")) |library_path| {
+            var it = mem.tokenizeScalar(u8, library_path, ':');
+            while (it.next()) |dir|
+                try self.addLibDir(dir);
+        } else |err| switch (err) {
+            error.InvalidWtf8 => unreachable,
+            error.EnvironmentVariableNotFound => {},
+            error.OutOfMemory => |e| return e,
+        }
+        if (!isCrossGuix(arena)) {
+            inline for ([_][]const u8{ "C_INCLUDE_PATH", "CPLUS_INCLUDE_PATH" }) |env_var| {
+                if (process.getEnvVarOwned(arena, env_var)) |include_path| {
+                    var it = mem.tokenizeScalar(u8, include_path, ':');
+                    while (it.next()) |dir|
+                        try self.addIncludeDir(dir);
+                } else |err| switch (err) {
+                    error.InvalidWtf8 => unreachable,
+                    error.EnvironmentVariableNotFound => {},
+                    error.OutOfMemory => |e| return e,
+                }
+            }
+            if (process.getEnvVarOwned(arena, "LIBRARY_PATH")) |library_path| {
+                var it = mem.tokenizeScalar(u8, library_path, ':');
+                while (it.next()) |dir|
+                    try self.addLibDir(dir);
+            } else |err| switch (err) {
+                error.InvalidWtf8 => unreachable,
+                error.EnvironmentVariableNotFound => {},
+                error.OutOfMemory => |e| return e,
+            }
+        }
+        return self;
+    }
     var is_nix = false;
     if (process.getEnvVarOwned(arena, "NIX_CFLAGS_COMPILE")) |nix_cflags_compile| {
         is_nix = true;
@@ -208,3 +253,11 @@ pub fn addWarningFmt(self: *NativePaths, comptime fmt: []const u8, args: anytype
 pub fn addRPath(self: *NativePaths, s: []const u8) !void {
     try self.rpaths.append(self.arena, s);
 }
+
+pub fn isCrossGuix(arena: Allocator) bool {
+    return process.hasEnvVar(arena, "CROSS_LIBRARY_PATH") catch false;
+}
+
+pub fn isGuix(arena: Allocator) bool {
+    return isCrossGuix(arena) or process.hasEnvVar(arena, "LIBRARY_PATH") catch false;
+}
diff --git a/src/main.zig b/src/main.zig
index 5b0e211647..d27b63d5a3 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -3706,7 +3706,8 @@ fn createModule(
         }
 
         // Trigger native system library path detection if necessary.
-        if (create_module.sysroot == null and
+        if (std.zig.system.NativePaths.isCrossGuix(arena) or
+            create_module.sysroot == null and
             resolved_target.is_native_os and resolved_target.is_native_abi and
             create_module.want_native_include_dirs)
         {
-- 
2.46.0