This patch fixes a memory leak bug. In particular, in a loop of the form "for X
of ...", with a type that has the Iterable aspect specified, if the result of
the Element function is returned on the secondary stack (e.g. the result
subtype has caller-unknown size), then memory for the secondary stack could
leak.
2018-05-30 Bob Duff <duff@adacore.com>
gcc/ada/
* exp_ch5.adb (Expand_Formal_Container_Element_Loop): Remove the code
to analyze the Elmt_Decl, because it gets analyzed in the wrong scope.
We need to analyze it as part of analyzing the block, so that if the
call to Element that initializes Elmt_Decl returns on the secondary
stack, the block will ss_mark/ss_release. This block is inside the
loop; we don't want to leak memory until the loop exits. The purpose
of analyzing Elmt_Decl first was to catch the error of modifying it,
which is illegal because it's a loop parameter. The above causes us to
miss that error. Therefore, we add a flag Is_Loop_Parameter, and set
it on the Element entity, so we end up with an E_Variable node with the
flag set.
* einfo.ads, einfo.adb (Is_Loop_Parameter): New flag.
* sem_ch5.adb (Diagnose_Non_Variable_Lhs): Give the "assignment to loop
parameter not allowed" error if Is_Loop_Parameter.
* sem_util.adb (Is_Variable): Return False if Is_Loop_Parameter, to
trigger the call to Diagnose_Non_Variable_Lhs.
From-SVN: r260930
