ada: Add new switch -gnatyz

Improve -gnatyx to check additional complete conditions,
and introduce a new switch -gnatyz to check for unnecessary
parentheses according to operator precedence rules.

Enable -gnatyz as part of -gnatyg.

gcc/ada/

	* par-ch5.adb, style.ads, styleg.adb, styleg.ads
	(Check_Xtra_Parens): Remove extra parameter Enable.
	(Check_Xtra_Parens_Precedence): New.
	(P_Case_Statement): Add -gnatyx style check.
	* sem_ch4.adb: Replace calls to Check_Xtra_Parens by
	Check_Xtra_Parens_Precedence.
	* stylesw.ads, stylesw.adb, usage.adb: Add support for
	-gnatyz.
	* doc/gnat_ugn/building_executable_programs_with_gnat.rst:
	Update -gnatyxzg doc.
	* sem_prag.adb, libgnat/s-regpat.adb,
	libgnarl/s-interr__hwint.adb, libgnarl/s-interr__vxworks.adb:
	Remove extra parens.
	* par-ch3.adb (P_Discrete_Range): Do not emit a style check if
	the expression is not a simple expression.
	* gnat_ugn.texi: Regenerate.

1 files changed, 7 insertions, 4 deletions

diff --git a/gcc/ada/styleg.ads b/gcc/ada/styleg.ads
index aa4f65e..7a610a1 100644
--- a/gcc/ada/styleg.ads
+++ b/gcc/ada/styleg.ads
@@ -160,10 +160,13 @@ package Styleg is
    procedure Check_Vertical_Bar;
    --  Called after scanning a vertical bar to check spacing
 
-   procedure Check_Xtra_Parens (N : Node_Id; Enable : Boolean);
-   --  Called after scanning an expression (N) that does not require an extra
-   --  level of parentheses around the entire expression.
-   --  Enable is a temporary parameter before enabling these checks by default.
+   procedure Check_Xtra_Parens (N : Node_Id);
+   --  Called after scanning an entire expression (N) that does not require an
+   --  extra level of parentheses.
+
+   procedure Check_Xtra_Parens_Precedence (N : Node_Id);
+   --  Called after scanning a subexpression (N) that does not require an
+   --  extra level of parentheses according to operator precedence rules.
 
    function Mode_In_Check return Boolean;
    pragma Inline (Mode_In_Check);