[Buildroot] [git commit] toolchain: linker options with a $ sign are not supported

[Thomas Petazzoni]

commit: http://git.buildroot.net/buildroot/commit/?id=a930d9cef6bdcf8de7d086ea66d977530200b8e0
branch: http://git.buildroot.net/buildroot/commit/?id=refs/heads/master

As reported in bug #7172 [0], setting BR2_TARGET_LDFLAGS to a value
containing a $ sign can lead to unexpected results.

This is because it is very hard to know when the $ sign gets evaluated:
  - in the Buildroot-level make
  - in the shell called by the Buildroot-level make
  - in the package's own build-system, either at configure time, in the
    Makefile, in a shell in the Makefile...

So, it is very difficult to know how much escaping that would need.

A proposal is to use a shell variable to pass such values unmolested.
But it is not that simple either, since it still contains a $ sign, and
there is not much certainty as to when it would be evaluated.

Instead, just document this limitation, both in the help text for
BR2_TARGET_LDFLAGS, and in the known-issues section in the manual.

Does not really fix #7172, but at least the limitation is documented.

[0] https://bugs.buildroot.org/show_bug.cgi?id=7172

Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
Cc: Mike Zick <minimod at morethan.org>
Reviewed-by: Thomas De Schampheleire <thomas.de.schampheleire at gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 docs/manual/known-issues.txt  |    4 ++++
 toolchain/toolchain-common.in |    3 +++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/docs/manual/known-issues.txt b/docs/manual/known-issues.txt
index 08469e9..5eaded9 100644
--- a/docs/manual/known-issues.txt
+++ b/docs/manual/known-issues.txt
@@ -3,6 +3,10 @@
 
 = Known issues
 
+* It is not possible to pass extra linker options via +BR2_TARGET_LDFLAGS+
+  if such options contain a +$+ sign. For example, the following is known
+  to break: +BR2_TARGET_LDFLAGS="-Wl,-rpath=\'$ORIGIN/../lib'"+
+
 * The +ltp-testsuite+ package does not build with the default uClibc
   configuration used by the Buildroot toolchain backend. The LTP
   testsuite uses several functions that are considered obsolete, such
diff --git a/toolchain/toolchain-common.in b/toolchain/toolchain-common.in
index 13de9e5..2df8ddb 100644
--- a/toolchain/toolchain-common.in
+++ b/toolchain/toolchain-common.in
@@ -132,6 +132,9 @@ config BR2_TARGET_LDFLAGS
 	help
 	  Extra options to pass to the linker when building for the target.
 
+	  Note that options with a '$' sign (eg. -Wl,-rpath='$ORIGIN/../lib')
+	  are not supported.
+
 config BR2_ECLIPSE_REGISTER
 	bool "Register toolchain within Eclipse Buildroot plug-in"
 	help