| Issue |
171844
|
| Summary |
[flang] rejection of valid code
|
| Labels |
flang:frontend
|
| Assignees |
|
| Reporter |
hmenke
|
No overindexing is happening in the subroutine `test` at runtime, yet flang rejects this code. Gfortran warns but accepts the code.
```fortran
subroutine test()
integer, parameter :: n = 1
real :: r(n)
r(1) = 1
if (n .eq. 2) then
r(2) = 2
end if
end subroutine test
```
```console
$ flang -c test.F90
error: Semantic errors in test.F90
./test.F90:6:5: error: subscript 2 is greater than upper bound 1 for dimension 1 of array
r(2) = 2
^^^^
./test.F90:3:11: Declaration of 'r'
real :: r(n)
^
```
Live demo https://godbolt.org/z/9qx69K14P
---
Source of the error message:
https://github.com/llvm/llvm-project/blob/16c0893f04c04faa8ac36495363344840f7c5db1/flang/lib/Semantics/_expression_.cpp#L344-L370
---
Proposed patch to downgrade the error to warning.
```patch
--- a/flang/lib/Semantics/_expression_.cpp
+++ b/flang/lib/Semantics/_expression_.cpp
@@ -349,17 +349,12 @@ static void ValidateSubscriptValue(parser::ContextualMessages &messages,
std::optional<ConstantSubscript> bound;
if (lb && val < *lb) {
msg =
- "%ssubscript %jd is less than lower %sbound %jd for %sdimension %d of array"_err_en_US;
+ "%ssubscript %jd is less than lower %sbound %jd for %sdimension %d of array"_warn_en_US;
bound = *lb;
} else if (ub && val > *ub) {
msg =
- "%ssubscript %jd is greater than upper %sbound %jd for %sdimension %d of array"_err_en_US;
+ "%ssubscript %jd is greater than upper %sbound %jd for %sdimension %d of array"_warn_en_US;
bound = *ub;
- if (dim + 1 == symbol.Rank() && IsDummy(symbol) && *bound == 1) {
- // Old-school overindexing of a dummy array isn't fatal when
- // it's on the last dimension and the extent is 1.
- msg->set_severity(parser::Severity::Warning);
- }
}
if (msg) {
AttachDeclaration(
```
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