From bec14225ab79b37be29ff15cf33e135158873f0a Mon Sep 17 00:00:00 2001
From: Randy Eckenrode <randy@largeandhighquality.com>
Date: Mon, 6 Nov 2023 16:49:22 -0500
Subject: [PATCH] gcc{48,49,6,7,8,9,10}: fix missing symbol errors on
 x86_64-darwin

The x86_64-darwin build fails with the following symbol errors when
building gencondmd:

    Undefined symbols for architecture x86_64:
      "_ix86_excess_precision", referenced from:
          ___cxx_global_var_init.101 in gencondmd.o
      "_ix86_fpmath", referenced from:
          ___cxx_global_var_init.101 in gencondmd.o
      "_ix86_isa_flags", referenced from:
          ___cxx_global_var_init.101 in gencondmd.o
      "_ix86_unsafe_math_optimizations", referenced from:
          ___cxx_global_var_init.101 in gencondmd.o
      "_target_flags", referenced from:
          ___cxx_global_var_init.101 in gencondmd.o

This commit applies a workaround posted to the GCC BugZilla.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92061.
---
 .../gcc/patches/clang-genconditions.patch     | 34 +++++++++++++++++++
 .../compilers/gcc/patches/default.nix         |  3 ++
 2 files changed, 37 insertions(+)
 create mode 100644 pkgs/development/compilers/gcc/patches/clang-genconditions.patch

diff --git a/pkgs/development/compilers/gcc/patches/clang-genconditions.patch b/pkgs/development/compilers/gcc/patches/clang-genconditions.patch
new file mode 100644
index 000000000000..655afd2abbc2
--- /dev/null
+++ b/pkgs/development/compilers/gcc/patches/clang-genconditions.patch
@@ -0,0 +1,34 @@
+From https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92061#c5
+
+--- a/gcc/genconditions.c	2019-01-01 12:37:19.064943662 +0100
++++ b/gcc/genconditions.c	2019-10-11 10:57:11.464595789 +0200
+@@ -57,8 +57,9 @@ write_header (void)
+ \n\
+ /* It is necessary, but not entirely safe, to include the headers below\n\
+    in a generator program.  As a defensive measure, don't do so when the\n\
+-   table isn't going to have anything in it.  */\n\
+-#if GCC_VERSION >= 3001\n\
++   table isn't going to have anything in it.\n\
++   Clang 9 is buggy and doesn't handle __builtin_constant_p correctly.  */\n\
++#if GCC_VERSION >= 3001 && __clang_major__ < 9\n\
+ \n\
+ /* Do not allow checking to confuse the issue.  */\n\
+ #undef CHECKING_P\n\
+@@ -170,7 +171,7 @@ struct c_test\n\
+    vary at run time.  It works in 3.0.1 and later; 3.0 only when not\n\
+    optimizing.  */\n\
+ \n\
+-#if GCC_VERSION >= 3001\n\
++#if GCC_VERSION >= 3001 && __clang_major__ < 9\n\
+ static const struct c_test insn_conditions[] = {\n");
+ 
+   traverse_c_tests (write_one_condition, 0);
+@@ -191,7 +192,7 @@ write_writer (void)
+ 	"  unsigned int i;\n"
+         "  const char *p;\n"
+         "  puts (\"(define_conditions [\");\n"
+-	"#if GCC_VERSION >= 3001\n"
++	"#if GCC_VERSION >= 3001 && __clang_major__ < 9\n"
+ 	"  for (i = 0; i < ARRAY_SIZE (insn_conditions); i++)\n"
+ 	"    {\n"
+ 	"      printf (\"  (%d \\\"\", insn_conditions[i].value);\n"
diff --git a/pkgs/development/compilers/gcc/patches/default.nix b/pkgs/development/compilers/gcc/patches/default.nix
index 4325c9f81677..2dd480fc6e57 100644
--- a/pkgs/development/compilers/gcc/patches/default.nix
+++ b/pkgs/development/compilers/gcc/patches/default.nix
@@ -194,6 +194,9 @@ in
   sha256 = "sha256-XtykrPd5h/tsnjY1wGjzSOJ+AyyNLsfnjuOZ5Ryq9vA=";
 })
 
+# Fix undefined symbol errors when building older versions with clang
+++ optional (!atLeast11 && stdenv.cc.isClang) ./clang-genconditions.patch
+
 
 ## gcc 9.0 and older ##############################################################################