[Buildroot] [git commit branch/2026.02.x] package/bootgen: fix build issue if host-flex already built

[Thomas Perale]

commit: https://gitlab.com/buildroot.org/buildroot/-/commit/0251ef146676d3fe14a9eaac50e087b1428aeba8
branch: https://gitlab.com/buildroot.org/buildroot/-/tree/2026.02.x

Fix a silent build issue with the host-bootgen package if host-flex is already
built. The host-flex package will install a version of the flexlexer.h header
file that is not compatible with the version embedded in bootgen.

While the build will still 'succeed', the binary will not be correct. This
can be seen by just running the binary that is built. By default, running
bootgen without any parameters should print the help menu, but if the wrong
version of flexlexer.h is used, it will print the following instead:

$ output/host/bin/bootgen

****** Bootgen v2025.1-Merged
  **** Build date : Mar 18 2026-07:08:01
    ** Copyright 1986-2022 Xilinx, Inc. All Rights Reserved.
    ** Copyright 2022-2025 Advanced Micro Devices, Inc. All Rights Reserved.

ERROR: syntax error
-h

Add a patch to the bootgen package that corrects the issue.

Upstream: CR to AMD jira

Signed-off-by: Neal Frager <neal.frager at amd.com>
Tested-by: Steven J. Hill <steven.hill at collins.com>
Signed-off-by: Julien Olivain <ju.o at free.fr>
(cherry picked from commit 75f62dc6693abd7f3880a75bd22b43e0ef74e12e)
Signed-off-by: Thomas Perale <thomas.perale at mind.be>
---
 ...exer-use-embedded-win_include-flexlexer.h.patch | 76 ++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/package/bootgen/0002-flexlexer-use-embedded-win_include-flexlexer.h.patch b/package/bootgen/0002-flexlexer-use-embedded-win_include-flexlexer.h.patch
new file mode 100644
index 0000000000..1de9a91223
--- /dev/null
+++ b/package/bootgen/0002-flexlexer-use-embedded-win_include-flexlexer.h.patch
@@ -0,0 +1,76 @@
+From dfe45e10791a171c3c79699257d3d3a978ec30eb Mon Sep 17 00:00:00 2001
+From: Neal Frager <neal.frager at amd.com>
+Date: Wed, 18 Mar 2026 09:51:58 +0000
+Subject: [PATCH] flexlexer: use embedded win_include/flexlexer.h
+
+bootgen embeds an old version of flex. If the host machine has a newer version
+of flex, the bootgen binary that is built will have errors such as the
+following, if the wrong version of flexlexer.h is used.
+
+$ output/host/bin/bootgen
+
+****** Bootgen v2025.1-Merged
+  **** Build date : Mar 18 2026-07:08:01
+    ** Copyright 1986-2022 Xilinx, Inc. All Rights Reserved.
+    ** Copyright 2022-2025 Advanced Micro Devices, Inc. All Rights Reserved.
+
+ERROR: syntax error
+-h
+
+Running the bootgen binary should print the help menu by default and should
+not have a syntax error.
+
+Correct the path to the flexlexer.h header files, such that no host version
+of these files can cause a silent build failure.
+
+Upstream: CR to AMD jira
+
+Signed-off-by: Neal Frager <neal.frager at amd.com>
+---
+ common/include/bifscanner.h        | 2 +-
+ common/include/cmdoptionsscanner.h | 2 +-
+ common/include/reginitscanner.h    | 2 +-
+ 3 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/common/include/bifscanner.h b/common/include/bifscanner.h
+index 9683416..9aa72a5 100755
+--- a/common/include/bifscanner.h
++++ b/common/include/bifscanner.h
+@@ -29,7 +29,7 @@
+ #if ! defined(yyFlexLexerOnce)
+ #undef yyFlexLexer
+ #define yyFlexLexer bifFlexLexer
+-#include "FlexLexer.h"
++#include "../../win_include/FlexLexer.h"
+ #endif
+ 
+ // Override the interface for yylex since we namespaced it
+diff --git a/common/include/cmdoptionsscanner.h b/common/include/cmdoptionsscanner.h
+index aa2f474..78fa7cf 100755
+--- a/common/include/cmdoptionsscanner.h
++++ b/common/include/cmdoptionsscanner.h
+@@ -30,7 +30,7 @@
+ 
+ #undef yyFlexLexer
+ #define yyFlexLexer reginitFlexLexer
+-#include "FlexLexer.h"
++#include "../../win_include/FlexLexer.h"
+ #endif
+ 
+ // Override the interface for yylex since we namespaced it
+diff --git a/common/include/reginitscanner.h b/common/include/reginitscanner.h
+index 74463e6..d8152a6 100755
+--- a/common/include/reginitscanner.h
++++ b/common/include/reginitscanner.h
+@@ -30,7 +30,7 @@
+ 
+ #undef yyFlexLexer
+ #define yyFlexLexer reginitFlexLexer
+-#include "FlexLexer.h"
++#include "../../win_include/FlexLexer.h"
+ #endif
+ 
+ // Override the interface for yylex since we namespaced it
+-- 
+2.25.1
+