compiler: get the dynamic linker from the target

instead of passing it to Compilation separately and storing it
separately in the linker options.

Author: andrewrk

src/Compilation.zig

@@ -812,7 +812,6 @@ pub const InitOptions = struct {
     main_mod: ?*Package.Module,
     output_mode: std.builtin.OutputMode,
     thread_pool: *ThreadPool,
-    dynamic_linker: ?[]const u8 = null,
     sysroot: ?[]const u8 = null,
     /// `null` means to not emit a binary file.
     emit_bin: ?EmitLoc,
@@ -1854,7 +1853,6 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
             .root_name = root_name,
             .module = module,
             .target = options.target,
-            .dynamic_linker = options.dynamic_linker,
             .sysroot = sysroot,
             .output_mode = options.output_mode,
             .link_mode = link_mode,
@@ -2824,7 +2822,7 @@ fn addNonIncrementalStuffToCacheManifest(comp: *Compilation, man: *Cache.Manifes
                 man.hash.addOptionalBytes(libc_installation.kernel32_lib_dir);
             }
         }
-        man.hash.addOptionalBytes(comp.bin_file.options.dynamic_linker);
+        man.hash.addOptionalBytes(target.dynamic_linker.get());
     }
     man.hash.addOptionalBytes(comp.bin_file.options.soname);
     man.hash.addOptional(comp.bin_file.options.version);

src/link.zig

@@ -103,7 +103,6 @@ pub const Options = struct {
     root_name: [:0]const u8,
     /// Not every Compilation compiles .zig code! For example you could do `zig build-exe foo.o`.
     module: ?*Module,
-    dynamic_linker: ?[]const u8,
     /// The root path for the dynamic linker and system libraries (as well as frameworks on Darwin)
     sysroot: ?[]const u8,
     /// Used for calculating how much space to reserve for symbols in case the binary file

src/link/Elf.zig

@@ -1574,7 +1574,7 @@ fn dumpArgv(self: *Elf, comp: *Compilation) !void {
         }
     } else {
         if (!self.isStatic()) {
-            if (self.base.options.dynamic_linker) |path| {
+            if (self.base.options.target.dynamic_linker.get()) |path| {
                 try argv.append("-dynamic-linker");
                 try argv.append(path);
             }
@@ -2374,7 +2374,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v
                 man.hash.addBytes(libc_installation.crt_dir.?);
             }
             if (have_dynamic_linker) {
-                man.hash.addOptionalBytes(self.base.options.dynamic_linker);
+                man.hash.addOptionalBytes(self.base.options.target.dynamic_linker.get());
             }
         }
         man.hash.addOptionalBytes(self.base.options.soname);
@@ -2687,7 +2687,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v
             }
 
             if (have_dynamic_linker) {
-                if (self.base.options.dynamic_linker) |dynamic_linker| {
+                if (self.base.options.target.dynamic_linker.get()) |dynamic_linker| {
                     try argv.append("-dynamic-linker");
                     try argv.append(dynamic_linker);
                 }
@@ -3503,7 +3503,7 @@ fn initSyntheticSections(self: *Elf) !void {
         // a segfault in the dynamic linker trying to load a binary that is static
         // and doesn't contain .dynamic section.
         if (self.isStatic() and !self.base.options.pie) break :blk false;
-        break :blk self.base.options.dynamic_linker != null;
+        break :blk self.base.options.target.dynamic_linker.get() != null;
     };
     if (needs_interp) {
         self.interp_section_index = try self.addSection(.{
@@ -4244,7 +4244,7 @@ fn updateSectionSizes(self: *Elf) !void {
     }
 
     if (self.interp_section_index) |index| {
-        self.shdrs.items[index].sh_size = self.base.options.dynamic_linker.?.len + 1;
+        self.shdrs.items[index].sh_size = self.base.options.target.dynamic_linker.get().?.len + 1;
     }
 
     if (self.hash_section_index) |index| {
@@ -4938,14 +4938,14 @@ fn writeSyntheticSections(self: *Elf) !void {
     const gpa = self.base.allocator;
 
     if (self.interp_section_index) |shndx| {
+        var buffer: [256]u8 = undefined;
+        const interp = self.base.options.target.dynamic_linker.get().?;
+        @memcpy(buffer[0..interp.len], interp);
+        buffer[interp.len] = 0;
+        const contents = buffer[0 .. interp.len + 1];
         const shdr = self.shdrs.items[shndx];
-        const sh_size = math.cast(usize, shdr.sh_size) orelse return error.Overflow;
-        var buffer = try gpa.alloc(u8, sh_size);
-        defer gpa.free(buffer);
-        const dylinker = self.base.options.dynamic_linker.?;
-        @memcpy(buffer[0..dylinker.len], dylinker);
-        buffer[dylinker.len] = 0;
-        try self.base.file.?.pwriteAll(buffer, shdr.sh_offset);
+        assert(shdr.sh_size == contents.len);
+        try self.base.file.?.pwriteAll(contents, shdr.sh_offset);
     }
 
     if (self.hash_section_index) |shndx| {

src/main.zig

@@ -3456,7 +3456,6 @@ fn buildOutputType(
         .target = target,
         .is_native_os = target_query.isNativeOs(),
         .is_native_abi = target_query.isNativeAbi(),
-        .dynamic_linker = target.dynamic_linker.get(),
         .sysroot = sysroot,
         .output_mode = output_mode,
         .main_mod = main_mod,
@@ -5287,7 +5286,6 @@ pub fn cmdBuild(gpa: Allocator, arena: Allocator, args: []const []const u8) !voi
             .target = target,
             .is_native_os = target_query.isNativeOs(),
             .is_native_abi = target_query.isNativeAbi(),
-            .dynamic_linker = target.dynamic_linker.get(),
             .output_mode = .Exe,
             .main_mod = &main_mod,
             .emit_bin = emit_bin,