Ignore system standard path when prepending environment variables

Summary:
Ignore /usr as prefix or kdedir when prepending environment variables to not
overrule user setting of PKG_CONFIG_PATH.

For me it was enough to fix my build with prepending CMAKE_PREFIX_PATH
conditionally, but in theory the other environment variables should also only
be prepended if it is not /usr to prepend.

Test Plan:
Compiled XCB 1.13 to /opt/xcb and have XCB 1.11 in /usr/.... Set
PKG_CONFIG_PATH to /opt/xcb/lib/pkgconfig.

Without this patch CMake, called by kdesrc-build, finds XCB 1.11 in
/usr/lib/x86_64-linux-gnu according to its log, but sets as version number
1.13 for some reason.

On make this fails. It still uses the lib from /opt/xcb> but does not include
the correct headers in opt/xcb/include.

With the patch CMake directly finds the lib in /opt/xcb and build succeeds.

Reviewers: bshah, mpyne

Reviewed By: mpyne

Subscribers:

Tags:

Differential Revision: https://phabricator.kde.org/D12739

modules/ksb/BuildSystem/KDE4.pm

@@ -32,8 +32,11 @@ sub prepareModuleBuildEnvironment
 {
     my ($self, $ctx, $module, $prefix) = @_;
 
-    $ctx->prependEnvironmentValue('CMAKE_PREFIX_PATH', $prefix);
-    $ctx->prependEnvironmentValue('XDG_DATA_DIRS', "$prefix/share");
+    # Avoid moving /usr up in env vars
+    if ($prefix ne '/usr') {
+        $ctx->prependEnvironmentValue('CMAKE_PREFIX_PATH', $prefix);
+        $ctx->prependEnvironmentValue('XDG_DATA_DIRS', "$prefix/share");
+    }
 
     my $qtdir = $module->getOption('qtdir');
     if ($qtdir && $qtdir ne $prefix) {

modules/ksb/Module.pm

@@ -657,14 +657,17 @@ sub setupEnvironment
     # Add global set-envs and context
     $self->buildContext()->applyUserEnvironment();
 
-    my @pkg_config_dirs = ("$kdedir/lib/pkgconfig");
-    $ctx->prependEnvironmentValue('PKG_CONFIG_PATH', @pkg_config_dirs);
+    # Avoid moving /usr up in env vars
+    if ($kdedir ne '/usr') {
+        my @pkg_config_dirs = ("$kdedir/lib/pkgconfig");
+        $ctx->prependEnvironmentValue('PKG_CONFIG_PATH', @pkg_config_dirs);
 
-    my @ld_dirs = ("$kdedir/lib", $self->getOption('libpath'));
-    $ctx->prependEnvironmentValue('LD_LIBRARY_PATH', @ld_dirs);
+        my @ld_dirs = ("$kdedir/lib", $self->getOption('libpath'));
+        $ctx->prependEnvironmentValue('LD_LIBRARY_PATH', @ld_dirs);
 
-    my @path = ("$kdedir/bin", $self->getOption('binpath'));
-    $ctx->prependEnvironmentValue('PATH', @path);
+        my @path = ("$kdedir/bin", $self->getOption('binpath'));
+        $ctx->prependEnvironmentValue('PATH', @path);
+    }
 
     # Build system's environment injection
     my $buildSystem = $self->buildSystem();