From a81fb5fb76131d0df3042f20e2d20a3b9216b254 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Wed, 4 Jun 2025 03:44:55 +0200
Subject: [PATCH] compiler: Rework PIE option logic.

To my knowledge, the only platforms that actually *require* PIE are Fuchsia and
Android, and the latter *only* when building a dynamically-linked executable.
OpenBSD and macOS both strongly encourage using PIE by default, but it isn't
technically required. So for the latter platforms, we enable it by default but
don't enforce it.

Also, importantly, if we're building an object file or a static library, and the
user hasn't explicitly told us whether to build PIE or non-PIE code (and the
target doesn't require PIE), we should *not* default to PIE. Doing so produces
code that cannot be linked into non-PIE output. In other words, building an
object file or a static library as PIE is an optimization only to be done when
the user knows that it'll end up in a PIE executable in the end.

Closes #21837.
---
 src/Compilation/Config.zig | 19 +++++++++++++------
 src/target.zig             |  4 ----
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/Compilation/Config.zig b/src/Compilation/Config.zig
index 12515520865171f75c701bb13c5386e2ae4e6d6e..3415acf33ed546d76a4779bcb0c964e232b5484a 100644
--- a/src/Compilation/Config.zig
+++ b/src/Compilation/Config.zig
@@ -416,22 +416,29 @@ pub fn resolve(options: Options) ResolveError!Config {
 
     const pie: bool = b: {
         switch (options.output_mode) {
-            .Obj, .Exe => {},
+            .Exe => if (target.os.tag == .fuchsia or
+                (target.abi.isAndroid() and link_mode == .dynamic))
+            {
+                if (options.pie == false) return error.TargetRequiresPie;
+                break :b true;
+            },
             .Lib => if (link_mode == .dynamic) {
                 if (options.pie == true) return error.DynamicLibraryPrecludesPie;
                 break :b false;
             },
-        }
-        if (target_util.requiresPIE(target)) {
-            if (options.pie == false) return error.TargetRequiresPie;
-            break :b true;
+            .Obj => {},
         }
         if (options.any_sanitize_thread) {
             if (options.pie == false) return error.SanitizeThreadRequiresPie;
             break :b true;
         }
         if (options.pie) |pie| break :b pie;
-        break :b false;
+        break :b if (options.output_mode == .Exe) switch (target.os.tag) {
+            .fuchsia,
+            .openbsd,
+            => true,
+            else => target.os.tag.isDarwin(),
+        } else false;
     };
 
     const root_strip = b: {
diff --git a/src/target.zig b/src/target.zig
index 4b0cc20bdad086c6e2243a8edae109356ba60392..81a1a4901f1b03ce4ec98aea5fc7aeaa8d8279b1 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -43,10 +43,6 @@ pub fn libCxxNeedsLibUnwind(target: std.Target) bool {
     };
 }
 
-pub fn requiresPIE(target: std.Target) bool {
-    return target.abi.isAndroid() or target.os.tag.isDarwin() or target.os.tag == .openbsd;
-}
-
 /// This function returns whether non-pic code is completely invalid on the given target.
 pub fn requiresPIC(target: std.Target, linking_libc: bool) bool {
     return target.abi.isAndroid() or
-- 
2.54.0