Commit 4797fdb3db6570ae65ff5f80cb1071307c42a244 | zig

author	Andrew Kelley <andrew@ziglang.org> 2020-12-11 13:15:58-07:00
committer	Andrew Kelley <andrew@ziglang.org> 2020-12-11 17:23:55-07:00
log	4797fdb3db6570ae65ff5f80cb1071307c42a244
tree	c1f05ac1432f2f47a960f2a86fabd862d2db1913
parent	74c17aa8c5bfff9ba13aaed7b978055d85709ede

fix deadlock with build-exe on an object for windows

The steps to repro this issue are:

zig build-obj hello.zig -target x86_64-windows-msvc
zig build-exe hello.obj -target x86_64-windows-msvc --subsystem console
-lkernel32 -lntdll

What was happening is that the main Compilation added a work item to
produce kernel32.lib. Then it added a sub-Compilation to build zig's
libc, which ended up calling a function with extern "kernel32", which
caused the sub-Compilation to also try to produce kernel32.lib. The main
Compilation and sub-Compilation do not coordinate about the set of
import libraries that they will be trying to build, so this caused a
deadlock.

This commit solves the problem by disabling the extern "foo" feature
from working when building compiler_rt or libc. Zig's linker code is now
responsible for putting the appropriate import libs on the linker line,
if any for compiler_rt and libc.

Related: #5825

4 files changed, 35 insertions(+), 0 deletions(-)

src
- Compilation.zig
test
- standalone.zig
- standalone
  - issue_5825
    build.zig
    main.zig

src/Compilation.zig+5

 @@ -3116,6 +3116,11 @@ pub fn build_crt_file(
 }
 pub fn stage1AddLinkLib(comp: *Compilation, lib_name: []const u8) !void {
+    // Avoid deadlocking on building import libs such as kernel32.lib
+    // This can happen when the user uses `build-exe foo.obj -lkernel32` and then
+    // when we create a sub-Compilation for zig libc, it also tries to build kernel32.lib.
+    if (comp.bin_file.options.is_compiler_rt_or_libc) return;
     // This happens when an `extern "foo"` function is referenced by the stage1 backend.
     // If we haven't seen this library yet and we're targeting Windows, we need to queue up
     // a work item to produce the DLL import library for this.

test/standalone.zig+1

...	@@ -15,6 +15,7 @@ pub fn addCases(cases: *tests.StandaloneContext) void {	...	@@ -15,6 +15,7 @@ pub fn addCases(cases: *tests.StandaloneContext) void {
15	cases.addBuildFile("test/standalone/static_c_lib/build.zig");	15	cases.addBuildFile("test/standalone/static_c_lib/build.zig");
16	cases.addBuildFile("test/standalone/issue_339/build.zig");	16	cases.addBuildFile("test/standalone/issue_339/build.zig");
17	cases.addBuildFile("test/standalone/issue_794/build.zig");	17	cases.addBuildFile("test/standalone/issue_794/build.zig");
		18	cases.addBuildFile("test/standalone/issue_5825/build.zig");
18	cases.addBuildFile("test/standalone/pkg_import/build.zig");	19	cases.addBuildFile("test/standalone/pkg_import/build.zig");
19	cases.addBuildFile("test/standalone/use_alias/build.zig");	20	cases.addBuildFile("test/standalone/use_alias/build.zig");
20	cases.addBuildFile("test/standalone/brace_expansion/build.zig");	21	cases.addBuildFile("test/standalone/brace_expansion/build.zig");

test/standalone/issue_5825/build.zig created+24

...	@@ -0,0 +1,24 @@
1	const Builder = @import("std").build.Builder;
2
3	pub fn build(b: *Builder) void {
4	const target = .{
5	.cpu_arch = .x86_64,
6	.os_tag = .windows,
7	.abi = .msvc,
8	};
9	const mode = b.standardReleaseOptions();
10	const obj = b.addObject("issue_5825", "main.zig");
11	obj.setTarget(target);
12	obj.setBuildMode(mode);
13
14	const exe = b.addExecutable("issue_5825", null);
15	exe.subsystem = .Console;
16	exe.linkSystemLibrary("kernel32");
17	exe.linkSystemLibrary("ntdll");
18	exe.setTarget(target);
19	exe.setBuildMode(mode);
20	exe.addObject(obj);
21
22	const test_step = b.step("test", "Test the program");
23	test_step.dependOn(&exe.step);
24	}

test/standalone/issue_5825/main.zig created+5

...	@@ -0,0 +1,5 @@
1	const std = @import("std");
2
3	pub fn main() anyerror!void {
4	std.log.info("All your codebase are belong to us.", .{});
5	}