From 981848b598c8a35a76c7fc226ac07852d9061f43 Mon Sep 17 00:00:00 2001 From: Bob Duff Date: Thu, 13 Oct 2022 16:51:08 -0400 Subject: ada: Suppress warnings on derived True/False GNAT normally warns on "return ...;" if the "..." is known to be True or False, but not when it is a Boolean literal True or False. This patch also suppresses the warning when the type is derived from Boolean, and has convention C or Fortran (and therefore True is represented as "nonzero"). Without this fix, GNAT would give warnings like "False is always False". gcc/ada/ * sem_warn.adb (Check_For_Warnings): Remove unnecessary exception handler. (Warn_On_Known_Condition): Suppress warning when we detect a True or False that has been turned into a more complex expression because True is represented as "nonzero". (Note that the complex expression will subsequently be constant-folded to a Boolean True or False). Also simplify to always print "condition is always ..." instead of special-casing object names. The special case was unhelpful, and indeed wrong when the expression is a literal. --- gcc/ada/sem_warn.adb | 119 +++++++++++++++++++++------------------------------ 1 file changed, 49 insertions(+), 70 deletions(-) (limited to 'gcc') diff --git a/gcc/ada/sem_warn.adb b/gcc/ada/sem_warn.adb index 9dccf0d..0a46c66 100644 --- a/gcc/ada/sem_warn.adb +++ b/gcc/ada/sem_warn.adb @@ -2948,21 +2948,6 @@ package body Sem_Warn is begin return Traverse (N) = Abandon; - - -- If any exception occurs, then something has gone wrong, and this is - -- only a minor aesthetic issue anyway, so just say we did not find what - -- we are looking for, rather than blow up. - - exception - when others => - -- With debug flag K we will get an exception unless an error has - -- already occurred (useful for debugging). - - if Debug_Flag_K then - Check_Error_Detected; - end if; - - return False; end Operand_Has_Warnings_Suppressed; ----------------------------------------- @@ -3379,11 +3364,10 @@ package body Sem_Warn is -- determined, and Test_Result is set True/False accordingly. Otherwise -- False is returned, and Test_Result is unchanged. - procedure Track (N : Node_Id; Loc : Node_Id); + procedure Track (N : Node_Id); -- Adds continuation warning(s) pointing to reason (assignment or test) -- for the operand of the conditional having a known value (or at least - -- enough is known about the value to issue the warning). N is the node - -- which is judged to have a known value. Loc is the warning location. + -- enough is known about the value to issue the warning). --------------------- -- Is_Known_Branch -- @@ -3417,36 +3401,45 @@ package body Sem_Warn is -- Track -- ----------- - procedure Track (N : Node_Id; Loc : Node_Id) is - Nod : constant Node_Id := Original_Node (N); + procedure Track (N : Node_Id) is - begin - if Nkind (Nod) in N_Op_Compare then - Track (Left_Opnd (Nod), Loc); - Track (Right_Opnd (Nod), Loc); + procedure Rec (Sub_N : Node_Id); + -- Recursive helper to do the work of Track, so we can refer to N's + -- Sloc in error messages. Sub_N is initially N, and a proper subnode + -- when recursively walking comparison operations. - elsif Is_Entity_Name (Nod) and then Is_Object (Entity (Nod)) then - declare - CV : constant Node_Id := Current_Value (Entity (Nod)); + procedure Rec (Sub_N : Node_Id) is + Orig : constant Node_Id := Original_Node (Sub_N); + begin + if Nkind (Orig) in N_Op_Compare then + Rec (Left_Opnd (Orig)); + Rec (Right_Opnd (Orig)); - begin - if Present (CV) then - Error_Msg_Sloc := Sloc (CV); + elsif Is_Entity_Name (Orig) and then Is_Object (Entity (Orig)) then + declare + CV : constant Node_Id := Current_Value (Entity (Orig)); + begin + if Present (CV) then + Error_Msg_Sloc := Sloc (CV); - if Nkind (CV) not in N_Subexpr then - Error_Msg_N ("\\??(see test #)", Loc); + if Nkind (CV) not in N_Subexpr then + Error_Msg_N ("\\??(see test #)", N); - elsif Nkind (Parent (CV)) = - N_Case_Statement_Alternative - then - Error_Msg_N ("\\??(see case alternative #)", Loc); + elsif Nkind (Parent (CV)) = + N_Case_Statement_Alternative + then + Error_Msg_N ("\\??(see case alternative #)", N); - else - Error_Msg_N ("\\??(see assignment #)", Loc); + else + Error_Msg_N ("\\??(see assignment #)", N); + end if; end if; - end if; - end; - end if; + end; + end if; + end Rec; + + begin + Rec (N); end Track; -- Local variables @@ -3464,11 +3457,8 @@ package body Sem_Warn is and then Is_Known_Branch then declare - Atrue : Boolean; - + Atrue : Boolean := Test_Result; begin - Atrue := Test_Result; - if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then Atrue := not Atrue; end if; @@ -3550,7 +3540,6 @@ package body Sem_Warn is declare True_Branch : Boolean := Test_Result; Cond : Node_Id := C; - begin if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not @@ -3559,37 +3548,27 @@ package body Sem_Warn is Cond := Parent (C); end if; - -- Condition always True - - if True_Branch then - if Is_Entity_Name (Original_Node (C)) - and then Nkind (Cond) /= N_Op_Not - then - Error_Msg_NE - ("object & is always True at this point?c?", - Cond, Original_Node (C)); - Track (Original_Node (C), Cond); + -- Suppress warning if this is True/False of a derived boolean + -- type with Nonzero_Is_True, which gets rewritten as Boolean + -- True/False. - else - Error_Msg_N ("condition is always True?c?", Cond); - Track (Cond, Cond); - end if; + if Is_Entity_Name (Original_Node (C)) + and then Ekind (Entity (Original_Node (C))) + = E_Enumeration_Literal + and then Nonzero_Is_True (Etype (Original_Node (C))) + then + null; - -- Condition always False + -- Give warning for nontrivial always True/False case else - if Is_Entity_Name (Original_Node (C)) - and then Nkind (Cond) /= N_Op_Not - then - Error_Msg_NE - ("object & is always False at this point?c?", - Cond, Original_Node (C)); - Track (Original_Node (C), Cond); - + if True_Branch then + Error_Msg_N ("condition is always True?c?", Cond); else Error_Msg_N ("condition is always False?c?", Cond); - Track (Cond, Cond); end if; + + Track (Cond); end if; end; end if; -- cgit v1.1