This gives the expected error message :

$ perl -lwe 'use File::Spec::Functions; my $x="x"; require(catfile($x,
+$x))'
Can't locate x/x in @INC ...
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As does this :

$ perl -lwe 'use File::Spec::Functions; my $x="x"; require join("/",$x
+,$x)'
Can't locate x/x in @INC ...
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But this gives a syntax error :

$ perl -lwe 'use File::Spec::Functions; my $x="x"; require catfile($x,
+$x)'
syntax error at -e line 1, near "require catfile("
Execution of -e aborted due to compilation errors.
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