Add support for --(no-)undefined-version

Co-authored-by: Motiejus Jakštys <motiejus@jakstys.lt>
Co-authored-by: Jakub Konka <kubkon@jakubkonka.com>
Co-authored-by: Samuel Cantero <scanterog@gmail.com>
Co-authored-by: Giorgos Georgiou <giorgos.georgiou@datadoghq.com>
Co-authored-by: Carl Åstholm <carl@astholm.se>

lib/std/Build/Step/Compile.zig

@@ -110,6 +110,9 @@ linker_dynamicbase: bool = true,
 
 linker_allow_shlib_undefined: ?bool = null,
 
+/// Allow version scripts to refer to undefined symbols.
+linker_allow_undefined_version: ?bool = null,
+
 /// Permit read-only relocations in read-only segments. Disallowed by default.
 link_z_notext: bool = false,
 
@@ -1451,6 +1454,9 @@ fn make(step: *Step, prog_node: *std.Progress.Node) !void {
         try zig_args.append("--version-script");
         try zig_args.append(version_script.getPath(b));
     }
+    if (self.linker_allow_undefined_version) |x| {
+        try zig_args.append(if (x) "--undefined-version" else "--no-undefined-version");
+    }
 
     if (self.kind == .@"test") {
         if (self.exec_cmd_args) |exec_cmd_args| {

src/Compilation.zig

@@ -1033,6 +1033,7 @@ pub const CreateOptions = struct {
     link_emit_relocs: bool = false,
     linker_script: ?[]const u8 = null,
     version_script: ?[]const u8 = null,
+    linker_allow_undefined_version: bool = false,
     soname: ?[]const u8 = null,
     linker_gc_sections: ?bool = null,
     linker_allow_shlib_undefined: ?bool = null,
@@ -1572,6 +1573,7 @@ pub fn create(gpa: Allocator, arena: Allocator, options: CreateOptions) !*Compil
             .stack_size = options.stack_size,
             .image_base = options.image_base,
             .version_script = options.version_script,
+            .allow_undefined_version = options.linker_allow_undefined_version,
             .gc_sections = options.linker_gc_sections,
             .emit_relocs = options.link_emit_relocs,
             .soname = options.soname,
@@ -2458,7 +2460,7 @@ fn prepareWholeEmitSubPath(arena: Allocator, opt_emit: ?EmitLoc) error{OutOfMemo
 /// to remind the programmer to update multiple related pieces of code that
 /// are in different locations. Bump this number when adding or deleting
 /// anything from the link cache manifest.
-pub const link_hash_implementation_version = 10;
+pub const link_hash_implementation_version = 11;
 
 fn addNonIncrementalStuffToCacheManifest(
     comp: *Compilation,
@@ -2467,7 +2469,7 @@ fn addNonIncrementalStuffToCacheManifest(
 ) !void {
     const gpa = comp.gpa;
 
-    comptime assert(link_hash_implementation_version == 10);
+    comptime assert(link_hash_implementation_version == 11);
 
     if (comp.module) |mod| {
         const main_zig_file = try mod.main_mod.root.joinString(arena, mod.main_mod.root_src_path);
@@ -2541,6 +2543,7 @@ fn addNonIncrementalStuffToCacheManifest(
 
     try man.addOptionalFile(opts.linker_script);
     try man.addOptionalFile(opts.version_script);
+    man.hash.add(opts.allow_undefined_version);
 
     man.hash.addOptional(opts.stack_size);
     man.hash.addOptional(opts.image_base);

src/link.zig

@@ -113,6 +113,7 @@ pub const File = struct {
         minor_subsystem_version: ?u16,
         gc_sections: ?bool,
         allow_shlib_undefined: ?bool,
+        allow_undefined_version: bool,
         subsystem: ?std.Target.SubSystem,
         linker_script: ?[]const u8,
         version_script: ?[]const u8,

src/link/Coff/lld.zig

@@ -70,7 +70,7 @@ pub fn linkWithLLD(self: *Coff, arena: Allocator, prog_node: *std.Progress.Node)
         man = comp.cache_parent.obtain();
         self.base.releaseLock();
 
-        comptime assert(Compilation.link_hash_implementation_version == 10);
+        comptime assert(Compilation.link_hash_implementation_version == 11);
 
         for (comp.objects) |obj| {
             _ = try man.addFile(obj.path, null);

src/link/Elf.zig

@@ -22,6 +22,7 @@ soname: ?[]const u8,
 bind_global_refs_locally: bool,
 linker_script: ?[]const u8,
 version_script: ?[]const u8,
+allow_undefined_version: bool,
 print_icf_sections: bool,
 print_map: bool,
 entry_name: ?[]const u8,
@@ -325,6 +326,7 @@ pub fn createEmpty(
         .bind_global_refs_locally = options.bind_global_refs_locally,
         .linker_script = options.linker_script,
         .version_script = options.version_script,
+        .allow_undefined_version = options.allow_undefined_version,
         .print_icf_sections = options.print_icf_sections,
         .print_map = options.print_map,
     };
@@ -2410,10 +2412,11 @@ fn linkWithLLD(self: *Elf, arena: Allocator, prog_node: *std.Progress.Node) !voi
         // We are about to obtain this lock, so here we give other processes a chance first.
         self.base.releaseLock();
 
-        comptime assert(Compilation.link_hash_implementation_version == 10);
+        comptime assert(Compilation.link_hash_implementation_version == 11);
 
         try man.addOptionalFile(self.linker_script);
         try man.addOptionalFile(self.version_script);
+        man.hash.add(self.allow_undefined_version);
         for (comp.objects) |obj| {
             _ = try man.addFile(obj.path, null);
             man.hash.add(obj.must_link);
@@ -2789,6 +2792,11 @@ fn linkWithLLD(self: *Elf, arena: Allocator, prog_node: *std.Progress.Node) !voi
                 try argv.append("-version-script");
                 try argv.append(version_script);
             }
+            if (self.allow_undefined_version) {
+                try argv.append("--undefined-version");
+            } else {
+                try argv.append("--no-undefined-version");
+            }
         }
 
         // Positional arguments to the linker such as object files.

src/link/MachO/zld.zig

@@ -55,7 +55,7 @@ pub fn linkWithZld(
         // We are about to obtain this lock, so here we give other processes a chance first.
         macho_file.base.releaseLock();
 
-        comptime assert(Compilation.link_hash_implementation_version == 10);
+        comptime assert(Compilation.link_hash_implementation_version == 11);
 
         for (objects) |obj| {
             _ = try man.addFile(obj.path, null);

src/link/Wasm.zig

@@ -3547,7 +3547,7 @@ fn linkWithZld(wasm: *Wasm, arena: Allocator, prog_node: *std.Progress.Node) lin
         // We are about to obtain this lock, so here we give other processes a chance first.
         wasm.base.releaseLock();
 
-        comptime assert(Compilation.link_hash_implementation_version == 10);
+        comptime assert(Compilation.link_hash_implementation_version == 11);
 
         for (objects) |obj| {
             _ = try man.addFile(obj.path, null);
@@ -4633,7 +4633,7 @@ fn linkWithLLD(wasm: *Wasm, arena: Allocator, prog_node: *std.Progress.Node) !vo
         // We are about to obtain this lock, so here we give other processes a chance first.
         wasm.base.releaseLock();
 
-        comptime assert(Compilation.link_hash_implementation_version == 10);
+        comptime assert(Compilation.link_hash_implementation_version == 11);
 
         for (comp.objects) |obj| {
             _ = try man.addFile(obj.path, null);

src/main.zig

@@ -500,6 +500,8 @@ const usage_build_generic =
     \\Global Link Options:
     \\  -T[script], --script [script]  Use a custom linker script
     \\  --version-script [path]        Provide a version .map file
+    \\  --undefined-version            Allow version scripts to refer to undefined symbols
+    \\  --no-undefined-version         (default) Disallow version scripts from referring to undefined symbols
     \\  --dynamic-linker [path]        Set the dynamic interpreter path (usually ld.so)
     \\  --sysroot [path]               Set the system root directory (usually /)
     \\  --version [ver]                Dynamic library semver
@@ -826,6 +828,7 @@ fn buildOutputType(
     var want_compiler_rt: ?bool = null;
     var linker_script: ?[]const u8 = null;
     var version_script: ?[]const u8 = null;
+    var linker_allow_undefined_version: bool = false;
     var disable_c_depfile = false;
     var linker_sort_section: ?link.File.Elf.SortSection = null;
     var linker_gc_sections: ?bool = null;
@@ -1200,6 +1203,10 @@ fn buildOutputType(
                         linker_script = args_iter.nextOrFatal();
                     } else if (mem.eql(u8, arg, "-version-script") or mem.eql(u8, arg, "--version-script")) {
                         version_script = args_iter.nextOrFatal();
+                    } else if (mem.eql(u8, arg, "--undefined-version")) {
+                        linker_allow_undefined_version = true;
+                    } else if (mem.eql(u8, arg, "--no-undefined-version")) {
+                        linker_allow_undefined_version = false;
                     } else if (mem.eql(u8, arg, "--library") or mem.eql(u8, arg, "-l")) {
                         // We don't know whether this library is part of libc
                         // or libc++ until we resolve the target, so we append
@@ -2153,6 +2160,10 @@ fn buildOutputType(
                     create_module.opts.rdynamic = true;
                 } else if (mem.eql(u8, arg, "-version-script") or mem.eql(u8, arg, "--version-script")) {
                     version_script = linker_args_it.nextOrFatal();
+                } else if (mem.eql(u8, arg, "--undefined-version")) {
+                    linker_allow_undefined_version = true;
+                } else if (mem.eql(u8, arg, "--no-undefined-version")) {
+                    linker_allow_undefined_version = false;
                 } else if (mem.eql(u8, arg, "-O")) {
                     linker_optimization = linker_args_it.nextOrFatal();
                 } else if (mem.startsWith(u8, arg, "-O")) {
@@ -3166,6 +3177,7 @@ fn buildOutputType(
         .hash_style = hash_style,
         .linker_script = linker_script,
         .version_script = version_script,
+        .linker_allow_undefined_version = linker_allow_undefined_version,
         .disable_c_depfile = disable_c_depfile,
         .soname = resolved_soname,
         .linker_sort_section = linker_sort_section,