The-OpenROAD-Project_OpenROAD/bazel/bison-patches/0001-gnulib-wrapper-headers-use-I-not-isystem.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Oyvind Harboe <oyvind.harboe@zylin.com>
Date: Mon, 6 Jul 2026 00:00:00 +0000
Subject: [PATCH] BUILD: let gnulib wrapper headers shadow libc via -I

Gnulib generates wrapper headers (lib/stdio.h, lib/fcntl.h, ...) that
must be found before the libc ones; they forward with #include_next and
add gnulib decorations (_GL_ATTRIBUTE_DEALLOC etc.) that lib/*-safer.h
and src/*.c rely on. The overlay's 'includes = ["lib"]' emits -isystem,
which loses to toolchains that inject libc headers as earlier -isystem
entries (e.g. the zero-sysroot hermetic-llvm BCR toolchain), and a dir
listed as both -I and -isystem is kept as -isystem, so the -I must
replace it, not merely accompany it.

Plain -I outranks every -isystem, restoring autotools' AM_CPPFLAGS =
-I./lib ordering. $(BINDIR) covers the generated wrappers, the source
path the checked-in ones.

Same class of fix as sed@4.9.bcr.5 (BCR #7915) and gawk@5.3.2.bcr.7
(BCR #7989); to be proposed upstream as bison@3.8.2.bcr.8.
---
diff --git a/BUILD.bazel b/BUILD.bazel
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -711,7 +711,19 @@
     tags = ["manual"],
 )
 
-BISON_COPTS = select({
+# Gnulib's wrapper headers (generated lib/stdio.h, lib/fcntl.h, ... plus
+# the checked-in lib/*-safer.h helpers) must shadow the libc headers: they
+# forward via #include_next and add gnulib decorations
+# (_GL_ATTRIBUTE_DEALLOC etc.) that lib/ and src/ sources rely on.
+# `includes = ["lib"]` emits -isystem, which loses against toolchains that
+# inject libc headers as earlier -isystem entries (e.g. the zero-sysroot
+# hermetic-llvm BCR toolchain). Plain -I outranks every -isystem (and a dir
+# listed as both -I and -isystem stays -isystem, so the -isystem form must
+# go entirely). This restores autotools' AM_CPPFLAGS = -I./lib ordering.
+BISON_COPTS = [
+    "-Iexternal/" + repo_name() + "/lib",
+    "-I$(BINDIR)/external/" + repo_name() + "/lib",
+] + select({
     "@rules_cc//cc/compiler:clang": [
         "-w",
         "-std=c11",
@@ -813,7 +825,6 @@
         "src/scan-skel.c",
         ":configmake_h_src",
     ],
-    includes = ["lib"],
     textual_hdrs = [
         "lib/timevar.def",
         "lib/printf-frexp.c",
@@ -997,6 +1008,7 @@
         "lib/main.c",
         "lib/yyerror.c",
     ],
+    copts = BISON_COPTS,
     implementation_deps = [":headers"],
     local_defines = LOCAL_DEFINES,
 )