[tor-commits] [tor/release-0.4.2] force pkg-config to only use --prefix when cross-compiling

[nickm at torproject.org]

commit 2a349006b9c1feba0a29ede4838cf8f5fdc0b2e5
Author: Hans-Christoph Steiner <hans at eds.org>
Date:   Tue Oct 29 21:13:56 2019 +0100

    force pkg-config to only use --prefix when cross-compiling
    
    The current pkg-config setup has no sense of whether it is cross-compiling,
    so it will detect things on the build system that are not present or are
    wrong for the host system.  This forces the cross-compiling build to only
    look for pkg-config .pc files in --prefix.
    
    A version of this has been the setup for many years with the Android builds.
    
    Fixes #32191
    
    Signed-off-by: Hans-Christoph Steiner <hans at eds.org>
---
 changes/ticket32191 |  3 +++
 configure.ac        | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/changes/ticket32191 b/changes/ticket32191
new file mode 100644
index 000000000..65e919fe0
--- /dev/null
+++ b/changes/ticket32191
@@ -0,0 +1,3 @@
+  o Minor features (build system):
+    - force pkg-config to only use --prefix when cross-compiling.
+      Closes ticket 32191.
diff --git a/configure.ac b/configure.ac
index 0e9bfe1f6..ece831d5b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -37,6 +37,16 @@ else
     pkg_config_user_action="check the PKG_CONFIG_PATH environment variable"
 fi
 
+if test "x$PKG_CONFIG_PATH" = "x" && test "x$prefix" != "xNONE" && test "$host" != "$build"; then
+   export PKG_CONFIG_PATH=$prefix/lib/pkgconfig
+   AC_MSG_NOTICE([set PKG_CONFIG_PATH=$PKG_CONFIG_PATH to support cross-compiling])
+   if test -f "$PKG_CONFIG_PATH/libevent.pc"; then
+       echo "checking for $PKG_CONFIG_PATH/libevent.pc... yes"
+   else
+       AC_MSG_ERROR([$PKG_CONFIG_PATH/libevent.pc not found!])
+   fi
+fi
+
 AC_ARG_ENABLE(openbsd-malloc,
    AS_HELP_STRING(--enable-openbsd-malloc, [use malloc code from OpenBSD.  Linux only. Deprecated: see --with-malloc]))
 AC_ARG_ENABLE(static-openssl,