Use cmd_args

Summary:
Refactors `get_framework_linker_args` and `_get_unchecked_framework_linker_args` to return `cmd_args` instead of `list[str]`, and uses `cmd_args(format=)` for library linker flags.

This avoids intermediate list allocations and leverages `cmd_args` composability — the unchecked path collapses from a loop with two appends per framework into a single `cmd_args(framework_names, prepend="-framework")`.

To measure the memory usage I ran:

```
$ buck2 kill
$ buck2 audit providers igios-no-extensions fbios-no-extensions --quiet
$ buck2 debug allocator-stats
```

Memory impact (jemalloc stats, before vs after):
- `allocated` is essentially unchanged (+31 MiB / +0.08% out of ~39 GiB), so the real heap footprint didn't move.
- `resident` (RSS) dropped by 1.6 GiB (-3.4%), from 47.6 GiB to 46.0 GiB, due to jemalloc's background purge thread reclaiming dirty pages more effectively.
- `retained` grew by 1.5 GiB (+5.9%), which is the mirror image — jemalloc kept the virtual address space mappings but released the physical pages back to the OS. This is free on 64-bit and allows cheap reuse without new mmap syscalls.
- `active / allocated` ratio (fragmentation) is stable at ~1.13x in both cases.

Overall: neutral to slightly positive. No regression in allocation pressure, improved RSS, no concerning tradeoffs.

Reviewed By: rmaz

Differential Revision: D92996049

fbshipit-source-id: 04e9fa2234b9c144fd9e0ccb4dac0e12a0f9f9c3

Author: Dustin Shahidehpour

prelude/apple/apple_framework_versions.bzl

@@ -1129,7 +1129,7 @@ def validate_sdk_frameworks(frameworks: list[str]) -> None:
             if framework_name not in FRAMEWORK_INTRODUCED_VERSIONS:
                 fail("Framework {} is missing version information".format(framework_name))
 
-def get_framework_linker_args(ctx: AnalysisContext, framework_names: list[str]) -> list[str]:
+def get_framework_linker_args(ctx: AnalysisContext, framework_names: list[str]) -> cmd_args:
     if not has_apple_toolchain(ctx):
         return _get_unchecked_framework_linker_args(framework_names)
 
@@ -1145,7 +1145,7 @@ def get_framework_linker_args(ctx: AnalysisContext, framework_names: list[str])
     if sdk_name.endswith("simulator"):
         sdk_name = sdk_name[:-len("simulator")] + "os"
 
-    args = []
+    args = cmd_args()
     for name in framework_names:
         versions = FRAMEWORK_INTRODUCED_VERSIONS.get(name, None)
         if versions:
@@ -1156,24 +1156,19 @@ def get_framework_linker_args(ctx: AnalysisContext, framework_names: list[str])
                 fail(message)
 
             if _version_is_greater_than(introduced, deployment_target):
-                args.append("-weak_framework")
+                args.add("-weak_framework")
             else:
-                args.append("-framework")
+                args.add("-framework")
         else:
             # Assume this is a non-SDK framework
-            args.append("-framework")
+            args.add("-framework")
 
-        args.append(name)
+        args.add(name)
 
     return args
 
-def _get_unchecked_framework_linker_args(framework_names: list[str]) -> list[str]:
-    args = []
-    for f in framework_names:
-        args.append("-framework")
-        args.append(f)
-
-    return args
+def _get_unchecked_framework_linker_args(framework_names: list[str]) -> cmd_args:
+    return cmd_args(framework_names, prepend = "-framework")
 
 def _version_is_greater_than(x: (int, int, int), y: (int, int, int)) -> bool:
     return x[0] > y[0] or (x[0] == y[0] and x[1] > y[1]) or (x[0] == y[0] and x[1] == y[1] and x[2] > y[2])

prelude/apple/apple_frameworks.bzl

@@ -62,9 +62,7 @@ def _get_apple_frameworks_linker_flags(ctx: AnalysisContext, linkables: list[[Fr
     expanded_frameworks_paths = _expand_sdk_framework_paths(ctx, unresolved_framework_paths)
     flags = _get_framework_search_path_flags(expanded_frameworks_paths)
     flags.add(get_framework_linker_args(ctx, framework_names))
-
-    for library in libraries:
-        flags.add("-l" + _library_name(library))
+    flags.add(cmd_args([_library_name(library) for library in libraries], format = "-l{}"))
 
     return flags