sys-devel/binutils-config: determine linker behaviour dynamically on Darwin

Whether or not we need to use a syslibroot, platform version or whatnot
depends on the platform and linker being in use.  Since the linker version can
differ from the macOS version, don't assume they are the same.

On Darwin, call the linker to establish its version prior to
constructing the final linker call arguments.  This is unfortunate, but
the only way it can somewhat reliably work with multiple linker versions
(as available from binutils-config) updating targets, and different
macOS versions.

Tested on:
Darwin  9, PPC, xtools-2.2.4 ld64-274.2
Darwin 17, X64, xtools-2.2.4 ld64-274.2
Darwin 23, X64, xtools-2.2.4 ld64-274.2
Darwin 23, M1,  native-5     ld64-650.9

Signed-off-by: Fabian Groffen <grobian@gentoo.org>

2 files changed, 68 insertions, 38 deletions

diff --git a/sys-devel/binutils-config/binutils-config-5.1-r7.ebuild b/sys-devel/binutils-config/binutils-config-5.1-r8.ebuild
index a26ff944b0..38f82d40b5 100644
--- a/sys-devel/binutils-config/binutils-config-5.1-r7.ebuild
+++ b/sys-devel/binutils-config/binutils-config-5.1-r8.ebuild
@@ -1,4 +1,4 @@
-# Copyright 1999-2021 Gentoo Authors
+# Copyright 1999-2024 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=6
@@ -39,12 +39,8 @@ src_configure() {
 src_compile() {
 	use prefix-guest || return
 	local extraargs=( )
-	if [[ ${CHOST} == *-darwin* && ${CHOST##*-darwin} -ge 20 ]] ; then
-		# macOS Big Sur has an empty /usr/lib, so the linker really has
-		# to look into the SDK, for which it needs to be told where it
-		# is (symlinked right into our EPREFIX root as MacOSX.sdk)
+	if [[ ${CHOST} == *-darwin* ]] ; then
 		extraargs+=(
-			-DDARWIN_LD_SYSLIBROOT=1
 			-DDARWIN_LD_DEFAULT_TARGET='"'${MACOSX_DEPLOYMENT_TARGET}'"'
 		)
 	fi
@@ -52,6 +48,7 @@ src_compile() {
 		$(tc-getCC)
 		${CPPFLAGS}
 		${CFLAGS}
+		-Wall
 		-o ldwrapper ${PN}-ldwrapper-${WRAPPER_REV}.c
 		-DEPREFIX=\"${EPREFIX}\"
 		-DCHOST=\"${CHOST}\"
diff --git a/sys-devel/binutils-config/files/ldwrapper.c b/sys-devel/binutils-config/files/ldwrapper.c
index df29b04c96..c9fe7e4bb3 100644
--- a/sys-devel/binutils-config/files/ldwrapper.c
+++ b/sys-devel/binutils-config/files/ldwrapper.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 1999-2023 Gentoo Authors
+ * Copyright 1999-2024 Gentoo Authors
  * Distributed under the terms of the GNU General Public License v2
  * Authors: Fabian Groffen <grobian@gentoo.org>
  *          Michael Haubenwallner <haubi@gentoo.org>
@@ -18,7 +18,7 @@
 
 /**
  * ldwrapper: Prefix helper to inject -L and -R flags to the invocation
- * of ld.
+ * of ld, and many more necessary linker flags/tweaks.
  *
  * On Darwin it adds -search_paths_first to make sure the given paths are
  * searched before the default search path, and sets -syslibroot
@@ -50,7 +50,6 @@ find_real_ld(char **ld, size_t ldlen, const char verbose, const char is_cross,
 	FILE *f = NULL;
 	char *ldoverride;
 	char *path;
-	char *ret;
 	struct stat lde;
 	char config[ESIZ];
 	size_t len;
@@ -203,12 +202,11 @@ main(int argc, char *argv[])
 	char *wrapperctarget = NULL;
 	char verbose = getenv("BINUTILS_CONFIG_VERBOSE") != NULL;
 	char *builddir = getenv("PORTAGE_BUILDDIR");
-	char ldbuf[ESIZ];
+	char ldbuf[ESIZ * 2];
 	char *ld = ldbuf;
 	char ctarget[128];
 	char *darwin_dt = getenv("MACOSX_DEPLOYMENT_TARGET");
 	int darwin_dt_ver = 0;
-	int darwin_ld_trg_ver = 0;
 	char is_cross = 0;
 	char is_darwin = 0;
 	char darwin_use_rpath = 1;
@@ -223,9 +221,6 @@ main(int argc, char *argv[])
 #ifdef DARWIN_LD_DEFAULT_TARGET
 	if (darwin_dt == NULL)
 		darwin_dt = DARWIN_LD_DEFAULT_TARGET;
-	darwin_ld_trg_ver = (int)strtol(DARWIN_LD_DEFAULT_TARGET, &p, 10) * 100;
-	if (*p == '.')
-		darwin_ld_trg_ver += (int)strtol(p + 1, &p, 10);
 #endif
 
 	/* two ways to determine CTARGET from argv[0]:
@@ -327,8 +322,6 @@ main(int argc, char *argv[])
 	 * non-cross-compilable on any platform, prefix or no prefix. So no
 	 * need to add PREFIX- or CTARGET-aware libdirs. */
 	if (!is_cross) {
-		struct stat st;
-
 		if (is_darwin) {
 			/* check deployment target if nothing prevents us from
 			 * using -rpath as of yet
@@ -356,10 +349,8 @@ main(int argc, char *argv[])
 			/* add the 2 prefix paths (-L) and -search_paths_first */
 			newargc += 2 + 1;
 
-#ifdef DARWIN_LD_SYSLIBROOT
 			/* add -syslibroot <path> -platform_version macos <ver> 0.0 */
 			newargc += 6;
-#endif
 		} else {
 			/* add the 4 paths we want (-L + -R) */
 			newargc += 8;
@@ -395,38 +386,81 @@ main(int argc, char *argv[])
 	newargv[j++] = ld;
 
 	if (!is_cross && is_darwin) {
-		char target[ESIZ];
-		ssize_t trglen;
-
-		/* ld64 will try to infer sdk version when -syslibroot is used
-		 * from the path given, unfortunately this searches for the
-		 * first numbers it finds, which means anything random in
-		 * EPREFIX, causing errors.  Explicitly set the deployment
-		 * version here, for the sdk link can be versionless when set to
-		 * CommandLineTools */
-#ifdef DARWIN_LD_SYSLIBROOT
-		/* bug #910277: transform into platform_version arg for newer
-		 * targets */
-		if (darwin_ld_trg_ver >= 1200) {
+		char  target[(2 * ESIZ) + 16];
+		FILE *ld64out;
+		int   ld64ver = 0;
+
+		/* call the linker to figure out what options we can use :(
+		 * some Developer Tools ld64 versions:
+		 * 12.0:   609      Big Sur, requirement for sdk_version
+		 * 13.0:   711
+		 * 13.3.1: 762
+		 * 14.0:   819.6
+		 * 14.2:   820.1
+		 * 14.3.1: 857.1
+		 * 15.0:   907      Sanoma, platform_version argument
+		 * all to be found from the PROJECT:ld64-650.9 bit from 1st line
+		 * NOTE: e.g. my Sanoma mac with CommandLineTools has 650.9
+		 *       which is not a version from any Developer Tools ?!?
+		 * Currently we need to distinguish XCode 15 according to
+		 * bug #910277, so we look for 907 and old targets before 12 */
+#define LD64_12_0  60900
+#define LD64_15_0  90700
+		snprintf(target, sizeof(target), "%s -v 2>&1", ld);
+		ld64out = popen(target, "r");
+		if (ld64out != NULL) {
+			char *proj;
+			long  comp;
+			if (fgets(target, sizeof(target), ld64out) != 0 &&
+				(proj = strstr(target, "PROJECT:ld64-")) != NULL)
+			{
+				proj += sizeof("PROJECT:ld64-") - 1;
+				comp  = strtol(proj, &proj, 10);
+				/* we currently have no need to parse fractions, the
+				 * major version is significant enough, so just stop */
+				ld64ver = (int)comp * 100;
+			}
+			pclose(ld64out);
+		}
+
+		/* macOS Big Sur (Darwin 20) has an empty /usr/lib, so the
+		 * linker really has to look into the SDK, for which it needs to
+		 * be told where it is (symlinked right into our EPREFIX root as
+		 * MacOSX.sdk) via the -syslibroot argument, older targets also
+		 * get this SDK path setup, old bootstraps would break, but that
+		 * would be easy to resolve -- there's unlikely to be many old
+		 * bootstraps out there that don't have the SDK path symlink */
+		newargv[j++] = "-syslibroot";
+		newargv[j++] = EPREFIX "/MacOSX.sdk";
+
+		/* ld64 will try to infer sdk version when -syslibroot is
+		 * used from the path given, unfortunately this searches for
+		 * the first numbers it finds, which means anything random
+		 * in EPREFIX, causing errors.  Explicitly set the
+		 * deployment version here, for the sdk link can be
+		 * versionless when set to CommandLineTools
+		 * macOS Sanoma however needs a new way to set this version,
+		 * so do the right thing */
+		if (ld64ver >= LD64_15_0) {
 			newargv[j++] = "-platform_version";
 			newargv[j++] = "macos";
 			newargv[j++] = darwin_dt;
 			newargv[j++] = "0.0";
-		} else {
+		} else if (ld64ver >= LD64_12_0) {
 			newargv[j++] = "-sdk_version";
 			newargv[j++] = darwin_dt;
+		} else {
+			newargv[j++] = "-macosx_version_min";
+			newargv[j++] = darwin_dt;
 		}
-		newargv[j++] = "-syslibroot";
-		newargv[j++] = EPREFIX "/MacOSX.sdk";
-#endif
-		/* inject this first to make the intention clear */
+
+		/* inject this before -L args to make the intention clear */
 		newargv[j++] = "-search_paths_first";
 	}
 
 	/* position k right after the original arguments */
 	k = j - 1 + argc;
 	for (i = 1; i < argc; i++, j++) {
-#ifdef DARWIN_LD_SYSLIBROOT
 		if (is_darwin) {
 			/* skip platform version stuff, we already pushed it out */
 			if ((strcmp(argv[i], "-macosx_version_min") == 0 ||
@@ -446,7 +480,6 @@ main(int argc, char *argv[])
 				continue;
 			}
 		}
-#endif
 
 		newargv[j] = argv[i];