[Mach-O] Handle $ld$install_name$ symbols

macho/tapi.cc

@@ -173,6 +173,17 @@ static void interpret_ld_symbols(Context<E> &ctx, TextDylib &tbd) {
         hidden_syms.insert(m[2]);
       continue;
     }
+
+    // $ld$install_name$os_version$name changes the install name to a
+    // given name.
+    static std::regex
+      install_name_re(R"(\$ld\$install_name\$os([\d.]+)\$(.+))", flags);
+
+    if (std::regex_match(name, m, install_name_re)) {
+      if (ctx.arg.platform_min_version == parse_version(m[1]))
+        tbd.install_name = save_string(ctx, m[2]);
+      continue;
+    }
   }
 
   for (std::string_view s : tbd.exports)

test/macho/tbd-install-name.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+export LC_ALL=C
+set -e
+CC="${TEST_CC:-cc}"
+CXX="${TEST_CXX:-c++}"
+GCC="${TEST_GCC:-gcc}"
+GXX="${TEST_GXX:-g++}"
+OBJDUMP="${OBJDUMP:-objdump}"
+MACHINE="${MACHINE:-$(uname -m)}"
+testname=$(basename "$0" .sh)
+echo -n "Testing $testname ... "
+cd "$(dirname "$0")"/../..
+t=out/test/macho/$testname
+mkdir -p $t
+
+cat > $t/libfoo.tbd <<'EOF'
+--- !tapi-tbd
+tbd-version:     4
+targets:         [ x86_64-macos, arm64-macos ]
+uuids:
+  - target:          x86_64-macos
+    value:           00000000-0000-0000-0000-000000000000
+  - target:          arm64-macos
+    value:           00000000-0000-0000-0000-000000000000
+install-name:    '/foo'
+current-version: 0
+compatibility-version: 0
+exports:
+  - targets:         [ x86_64-macos, arm64-macos ]
+    symbols:         [ '$ld$install_name$os25.0$/bar', _foo ]
+...
+EOF
+
+cat <<EOF | clang -o $t/a.o -c -xc -
+void foo();
+int main() { foo(); }
+EOF
+
+clang --ld-path=./ld64 -o $t/exe1 $t/libfoo.tbd $t/a.o \
+  -Wl,-platform_version,macos,20.0,20.0 >& /dev/null
+
+otool -L $t/exe1 | grep -q /foo
+
+clang --ld-path=./ld64 -o $t/exe2 $t/libfoo.tbd $t/a.o \
+  -Wl,-platform_version,macos,25.0,21.0 >& /dev/null
+
+otool -L $t/exe2 | grep -q /bar
+
+echo OK