diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst | 5 | ||||
| -rw-r--r-- | gcc/ada/gnat_ugn.texi | 4 | ||||
| -rw-r--r-- | gcc/ada/opt.ads | 5 | ||||
| -rw-r--r-- | gcc/ada/sem_res.adb | 22 | ||||
| -rw-r--r-- | gcc/ada/usage.adb | 6 |
5 files changed, 36 insertions, 6 deletions
diff --git a/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst b/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst index fb8a3ff..0906a68 100644 --- a/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst +++ b/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst @@ -3424,7 +3424,10 @@ of the pragma in the :title:`GNAT_Reference_manual`). with no size clause. The guess in both cases is that 2**x was intended rather than x. In addition expressions of the form 2*x for small x generate a warning (the almost certainly accurate guess being that - 2**x was intended). The default is that these warnings are given. + 2**x was intended). This switch also activates warnings for negative + literal values of a modular type, which are interpreted as large positive + integers after wrap-around. The default is that these warnings are given. + .. index:: -gnatw.M (gcc) diff --git a/gcc/ada/gnat_ugn.texi b/gcc/ada/gnat_ugn.texi index 637f061..fefba9c 100644 --- a/gcc/ada/gnat_ugn.texi +++ b/gcc/ada/gnat_ugn.texi @@ -11616,7 +11616,9 @@ a modulus of 7 with a size of 7 bits), and modulus values of 32 or 64 with no size clause. The guess in both cases is that 2**x was intended rather than x. In addition expressions of the form 2*x for small x generate a warning (the almost certainly accurate guess being that -2**x was intended). The default is that these warnings are given. +2**x was intended). This switch also activates warnings for negative +literal values of a modular type, which are interpreted as large positive +integers after wrap-around. The default is that these warnings are given. @end table @geindex -gnatw.M (gcc) diff --git a/gcc/ada/opt.ads b/gcc/ada/opt.ads index f717a99..aeac352 100644 --- a/gcc/ada/opt.ads +++ b/gcc/ada/opt.ads @@ -1885,8 +1885,9 @@ package Opt is Warn_On_Suspicious_Modulus_Value : Boolean := True; -- GNAT - -- Set to True to generate warnings for suspicious modulus values. The - -- default is that this warning is enabled. Modified by -gnatw.m/.M. + -- Set to True to generate warnings for suspicious modulus values, as well + -- as negative literals of a modular type. The default is that this warning + -- is enabled. Modified by -gnatw.m/.M. Warn_On_Unchecked_Conversion : Boolean := True; -- GNAT diff --git a/gcc/ada/sem_res.adb b/gcc/ada/sem_res.adb index fc89a31..bd950f5 100644 --- a/gcc/ada/sem_res.adb +++ b/gcc/ada/sem_res.adb @@ -12096,6 +12096,28 @@ package body Sem_Res is Set_Etype (N, B_Typ); Resolve (R, B_Typ); + -- Generate warning for negative literal of a modular type, unless it is + -- enclosed directly in a type qualification or a type conversion, as it + -- is likely not what the user intended. We don't issue the warning for + -- the common use of -1 to denote OxFFFF_FFFF... + + if Warn_On_Suspicious_Modulus_Value + and then Nkind (N) = N_Op_Minus + and then Nkind (R) = N_Integer_Literal + and then Is_Modular_Integer_Type (B_Typ) + and then Nkind (Parent (N)) not in N_Qualified_Expression + | N_Type_Conversion + and then Expr_Value (R) > Uint_1 + then + Error_Msg_N + ("?M?negative literal of modular type is in fact positive", N); + Error_Msg_Uint_1 := (-Expr_Value (R)) mod Modulus (B_Typ); + Error_Msg_Uint_2 := Expr_Value (R); + Error_Msg_N ("\do you really mean^ when writing -^ '?", N); + Error_Msg_N + ("\if you do, use qualification to avoid this warning", N); + end if; + -- Generate warning for expressions like abs (x mod 2) if Warn_On_Redundant_Constructs diff --git a/gcc/ada/usage.adb b/gcc/ada/usage.adb index e5bc62e..c85d610 100644 --- a/gcc/ada/usage.adb +++ b/gcc/ada/usage.adb @@ -532,8 +532,10 @@ begin "but not read"); Write_Line (" M* turn off warnings for variable assigned " & "but not read"); - Write_Line (" .m*+ turn on warnings for suspicious modulus value"); - Write_Line (" .M turn off warnings for suspicious modulus value"); + Write_Line (" .m*+ turn on warnings for suspicious usage " & + "of modular type"); + Write_Line (" .M turn off warnings for suspicious usage " & + "of modular type"); Write_Line (" n* normal warning mode (cancels -gnatws/-gnatwe)"); Write_Line (" .n turn on info messages for atomic " & "synchronization"); |