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author | Bob Duff <duff@adacore.com> | 2021-12-10 06:01:22 -0500 |
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committer | Pierre-Marie de Rodat <derodat@adacore.com> | 2022-01-06 17:11:42 +0000 |
commit | 2a60c08e98acaae212840b2d3329b5bd13778581 (patch) | |
tree | 2b00cc1deb87a7f7e19d77777f72e98726150e5e /gcc/ada/sem_res.adb | |
parent | 1871f2cb3cef93485a11057b1bb9aff2c68dd512 (diff) | |
download | gcc-2a60c08e98acaae212840b2d3329b5bd13778581.zip gcc-2a60c08e98acaae212840b2d3329b5bd13778581.tar.gz gcc-2a60c08e98acaae212840b2d3329b5bd13778581.tar.bz2 |
[Ada] Warn on subtype declaration of null range
gcc/ada/
* sem_res.adb (Resolve_Range): Warn on null range, unless we are
inside a generic unit or an instance thereof.
* sem_ch3.adb (Analyze_Subtype_Indication): Minor: avoid double
negative.
Diffstat (limited to 'gcc/ada/sem_res.adb')
-rw-r--r-- | gcc/ada/sem_res.adb | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb index 9a63506..44b0414 100644 --- a/gcc/ada/sem_res.adb +++ b/gcc/ada/sem_res.adb @@ -10754,6 +10754,30 @@ package body Sem_Res is Fold_Uint (H, Expr_Value (H), Static => True); end if; end if; + + -- If we have a compile-time-known null range, we warn, because that is + -- likely to be a mistake. (Dynamic null ranges make sense, but often + -- compile-time-known ones do not.) Warn only if this is in a subtype + -- declaration. We do this here, rather than while analyzing a subtype + -- declaration, in case we decide to expand the cases. We do not want to + -- warn in all cases, because some are idiomatic, such as an empty + -- aggregate (1 .. 0 => <>). + + -- We don't warn in generics or their instances, because there might be + -- some instances where the range is null, and some where it is not, + -- which would lead to false alarms. + + if not (Inside_A_Generic or In_Instance) + and then Comes_From_Source (N) + and then Compile_Time_Compare + (Low_Bound (N), High_Bound (N), Assume_Valid => True) = GT + and then Nkind (Parent (N)) = N_Range_Constraint + and then Nkind (Parent (Parent (N))) = N_Subtype_Indication + and then Nkind (Parent (Parent (Parent (N)))) = N_Subtype_Declaration + and then Is_OK_Static_Range (N) + then + Error_Msg_N ("null range??", N); + end if; end Resolve_Range; -------------------------- |