lib: add support for omitting soname

This commit adds the `soname` option for `Build.Module` and
`OverlayOptions`. This controls whether `-fsoname` or `-fno-soname` is
passed to the linker. The `SOName` type is moved to `std.zig` to make
it accessible in other modules.

This is needed to implement the new test in
#19818

Author: a-khabarov

lib/std/Build/Module.zig

@@ -18,6 +18,7 @@ frameworks: std.StringArrayHashMapUnmanaged(LinkFrameworkOptions),
 link_objects: std.ArrayListUnmanaged(LinkObject),
 
 strip: ?bool,
+soname: ?std.zig.SOName,
 unwind_tables: ?std.builtin.UnwindTables,
 single_threaded: ?bool,
 stack_protector: ?bool,
@@ -251,6 +252,7 @@ pub const CreateOptions = struct {
     link_libcpp: ?bool = null,
     single_threaded: ?bool = null,
     strip: ?bool = null,
+    soname: ?std.zig.SOName = null,
     unwind_tables: ?std.builtin.UnwindTables = null,
     dwarf_format: ?std.dwarf.Format = null,
     code_model: std.builtin.CodeModel = .default,
@@ -300,6 +302,7 @@ pub fn init(
                 .frameworks = .{},
                 .link_objects = .{},
                 .strip = options.strip,
+                .soname = options.soname,
                 .unwind_tables = options.unwind_tables,
                 .single_threaded = options.single_threaded,
                 .stack_protector = options.stack_protector,
@@ -566,6 +569,14 @@ pub fn appendZigProcessFlags(
     try addFlag(zig_args, m.pic, "-fPIC", "-fno-PIC");
     try addFlag(zig_args, m.red_zone, "-mred-zone", "-mno-red-zone");
 
+    if (m.soname) |soname| {
+        try zig_args.append(switch (soname) {
+            .no => "-fno-soname",
+            .yes_default_value => "-fsoname",
+            .yes => |value| b.fmt("-fsoname={s}", .{value}),
+        });
+    }
+
     if (m.dwarf_format) |dwarf_format| {
         try zig_args.append(switch (dwarf_format) {
             .@"32" => "-gdwarf32",

lib/std/zig.zig

@@ -315,6 +315,12 @@ pub const BuildId = union(enum) {
 
 pub const LtoMode = enum { none, full, thin };
 
+pub const SOName = union(enum) {
+    no,
+    yes_default_value,
+    yes: []const u8,
+};
+
 /// Renders a `std.Target.Cpu` value into a textual representation that can be parsed
 /// via the `-mcpu` flag passed to the Zig compiler.
 /// Appends the result to `buffer`.

src/main.zig

@@ -16,6 +16,7 @@ const native_os = builtin.os.tag;
 const Cache = std.Build.Cache;
 const Path = std.Build.Cache.Path;
 const Directory = std.Build.Cache.Directory;
+const SOName = std.zig.SOName;
 const EnvVar = std.zig.EnvVar;
 const LibCInstallation = std.zig.LibCInstallation;
 const AstGen = std.zig.AstGen;
@@ -688,12 +689,6 @@ const usage_build_generic =
     \\
 ;
 
-const SOName = union(enum) {
-    no,
-    yes_default_value,
-    yes: []const u8,
-};
-
 const EmitBin = union(enum) {
     no,
     yes_default_path,

test/link/link.zig

@@ -44,6 +44,7 @@ const OverlayOptions = struct {
     zig_source_bytes: ?[]const u8 = null,
     pic: ?bool = null,
     strip: ?bool = null,
+    soname: ?std.zig.SOName = null,
 };
 
 pub fn addExecutable(b: *std.Build, base: Options, overlay: OverlayOptions) *Compile {
@@ -97,6 +98,7 @@ fn createModule(b: *Build, base: Options, overlay: OverlayOptions) *Build.Module
         },
         .pic = overlay.pic,
         .strip = if (base.strip) |s| s else overlay.strip,
+        .soname = overlay.soname,
     });
 
     if (overlay.objcpp_source_bytes) |bytes| {