[clang] [FreeBSD] Support -stdlib=libstdc++ (PR #126302)

[Alexander Richardson via cfe-commits]

https://github.com/arichardson created https://github.com/llvm/llvm-project/pull/126302

The experimental-library-flag.cpp test was failing on FreeBSD builders,
which turned to be caused by missing support for -stdlib=libcstdc++ (and
just using a hardcoded libc++ in all cases).
Simplify FreeBSD::AddCXXStdlibLibArgs() by deferring to the parent class
and dealing with the FreeSBD < 14 profiling support as a special case.


>From 6b89c65eb61a7c2565b96caedd11eb2efff61021 Mon Sep 17 00:00:00 2001
From: Alex Richardson <alexrichardson at google.com>
Date: Fri, 7 Feb 2025 12:14:20 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.6-beta.1
---
 clang/lib/Driver/ToolChains/FreeBSD.cpp         | 10 +++++-----
 clang/test/Driver/experimental-library-flag.cpp |  5 +++++
 clang/test/Driver/freebsd.cpp                   |  8 ++++++--
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/FreeBSD.cpp b/clang/lib/Driver/ToolChains/FreeBSD.cpp
index a6d859f0ebfec23..bd6ab0f8aba5768 100644
--- a/clang/lib/Driver/ToolChains/FreeBSD.cpp
+++ b/clang/lib/Driver/ToolChains/FreeBSD.cpp
@@ -452,12 +452,12 @@ void FreeBSD::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
 
 void FreeBSD::AddCXXStdlibLibArgs(const ArgList &Args,
                                   ArgStringList &CmdArgs) const {
+  Generic_ELF::AddCXXStdlibLibArgs(Args, CmdArgs);
   unsigned Major = getTriple().getOSMajorVersion();
-  bool Profiling = Args.hasArg(options::OPT_pg) && Major != 0 && Major < 14;
-
-  CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++");
-  if (Args.hasArg(options::OPT_fexperimental_library))
-    CmdArgs.push_back("-lc++experimental");
+  bool SuffixedLib = Args.hasArg(options::OPT_pg) && Major != 0 && Major < 14;
+  if (SuffixedLib && GetCXXStdlibType(Args) == CST_Libcxx)
+    llvm::replace(CmdArgs, static_cast<const char *>("-lc++"),
+                  static_cast<const char *>("-lc++_p"));
 }
 
 void FreeBSD::AddCudaIncludeArgs(const ArgList &DriverArgs,
diff --git a/clang/test/Driver/experimental-library-flag.cpp b/clang/test/Driver/experimental-library-flag.cpp
index db6a90b50f2553c..62b007516897e4b 100644
--- a/clang/test/Driver/experimental-library-flag.cpp
+++ b/clang/test/Driver/experimental-library-flag.cpp
@@ -9,6 +9,11 @@
 // RUN: %clangxx -fexperimental-library -stdlib=libstdc++ -### %s 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-LIBSTDCXX %s
 // RUN: %clangxx -fexperimental-library -stdlib=libc++ -nostdlib++ -### %s 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-NOSTDLIB %s
 
+/// The FreeBSD driver did not support -stdlib=libstdc++ previously, check that it does the right thing here.
+// RUN: %clangxx --target=x86_64-unknown-freebsd -fexperimental-library -stdlib=libc++ -### %s 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-LIBCXX %s
+// RUN: %clangxx --target=x86_64-unknown-freebsd -fexperimental-library -stdlib=libstdc++ -### %s 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-LIBSTDCXX %s
+// RUN: %clangxx --target=x86_64-unknown-freebsd -fexperimental-library -stdlib=libc++ -nostdlib++ -### %s 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-NOSTDLIB %s
+
 // -fexperimental-library must be passed to CC1.
 // CHECK: -fexperimental-library
 
diff --git a/clang/test/Driver/freebsd.cpp b/clang/test/Driver/freebsd.cpp
index dc8c98d3c3cb749..af6b873a387f13c 100644
--- a/clang/test/Driver/freebsd.cpp
+++ b/clang/test/Driver/freebsd.cpp
@@ -1,9 +1,13 @@
 // RUN: %clangxx %s -### -o %t.o --target=amd64-unknown-freebsd -stdlib=platform 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-DEFAULT %s
 // RUN: %clangxx %s -### -o %t.o --target=amd64-unknown-freebsd10.0 -stdlib=platform 2>&1 \
-// RUN:   | FileCheck --check-prefix=CHECK-TEN %s
+// RUN:   | FileCheck --check-prefix=CHECK-DEFAULT %s
+// RUN: %clangxx %s -### -o %t.o --target=amdf64-unknown-freebsd -stdlib=libc++ 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-DEFAULT %s
+// RUN: %clangxx %s -### -o %t.o --target=amd64-unknown-freebsd -stdlib=libstdc++ 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-STDLIBCXX %s
 // CHECK-DEFAULT: "-lc++" "-lm"
-// CHECK-TEN: "-lc++" "-lm"
+// CHECK-STDLIBCXX: "-lstdc++" "-lm"
 
 // RUN: %clangxx %s -### -pg -o %t.o --target=amd64-unknown-freebsd -stdlib=platform 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-PG-DEFAULT %s