https://gcc.gnu.org/g:4e96f7fc8e1997e55dc7bd47d59b33b6010a892f
commit r16-1341-g4e96f7fc8e1997e55dc7bd47d59b33b6010a892f
Author: Gary Dismukes <dismu...@adacore.com>
Date: Mon Mar 17 18:30:00 2025 +0000
ada: Support fixed-lower-bound array types as generic actual parameters
Attempting to use a fixed-lower-bound array type (or subtype) as
an actual parameter for a formal unconstrained array type was being
rejected by the compiler (complaining about the index type of the
actual not matching the index type of the formal type). The compiler
was improperly testing the actual's FLB range and finding that it didn't
statically match the index type of the formal array type; it should
instead test the underlying index type of the FLB type or subtype.
gcc/ada/ChangeLog:
* sem_ch3.adb (Constrain_Index): In the case of a fixed-lower-bound
index,
set Etype of the newly created itype's Scalar_Range from the
index's Etype.
* sem_ch12.adb (Validate_Array_Type_Instance): If the actual
subtype is
a fixed-lower-bound type, then check again the Etype of its
Scalar_Range.
Diff:
---
gcc/ada/sem_ch12.adb | 10 ++++++++++
gcc/ada/sem_ch3.adb | 4 +++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/gcc/ada/sem_ch12.adb b/gcc/ada/sem_ch12.adb
index 3a31a921fe31..c9b9e7f87eca 100644
--- a/gcc/ada/sem_ch12.adb
+++ b/gcc/ada/sem_ch12.adb
@@ -14129,6 +14129,16 @@ package body Sem_Ch12 is
T2 := Etype (I2);
end if;
+ -- In the case of a fixed-lower-bound subtype, we want to check
+ -- against the index type's range rather than the range of the
+ -- subtype (which will be seen as unconstrained, and whose bounds
+ -- won't generally match those of the formal unconstrained array
+ -- type's corresponding index type).
+
+ if Is_Fixed_Lower_Bound_Index_Subtype (T2) then
+ T2 := Etype (Scalar_Range (T2));
+ end if;
+
if not Subtypes_Match
(Find_Actual_Type (Etype (I1), A_Gen_T), T2)
then
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index 9d93bf79c0ce..1263d7004d9f 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -15099,7 +15099,8 @@ package body Sem_Ch3 is
-- If this is a range for a fixed-lower-bound subtype, then set the
-- index itype's low bound to the FLB and the index itype's upper bound
-- to the high bound of the parent array type's index subtype. Also,
- -- mark the itype as an FLB index subtype.
+ -- set the Etype of the new scalar range and mark the itype as an FLB
+ -- index subtype.
if Nkind (S) = N_Range and then Is_FLB_Index then
Set_Scalar_Range
@@ -15107,6 +15108,7 @@ package body Sem_Ch3 is
Make_Range (Sloc (S),
Low_Bound => Low_Bound (S),
High_Bound => Type_High_Bound (T)));
+ Set_Etype (Scalar_Range (Def_Id), Etype (Index));
Set_Is_Fixed_Lower_Bound_Index_Subtype (Def_Id);
else
