ada: Turn assertions into defensive code in error locations

We pretty-print numeric literals that do not come from source by relying
on their Sloc. This generally works well, but sporadically the Sloc is
set wrongly. We might want to trace and fix such occurrences, but for
now it is simpler to replace an otherwise reasonable assertions with
defensive code.

gcc/ada/

	* errout.adb (Last_Sloc): Refactor a heavily repeated "S := S + 1"
	statement into a subprogram; replace assertions with defensive code;
	fix few more off-by-one errors.

diff --git a/gcc/ada/errout.adb b/gcc/ada/errout.adb
index 6531410f0d230c0cea0543bdd2e9ac47b44db793..1c6222b3a2945775f7b941789c25eae3404a6664 100644 (file)
--- a/gcc/ada/errout.adb
+++ b/gcc/ada/errout.adb
@@ -1994,6 +1994,20 @@ package body Errout is
    ---------------
 
    function Last_Sloc (N : Node_Id) return Source_Ptr is
+      procedure Skip_Char (S : in out Source_Ptr);
+      --  Skip one character of the source buffer at location S
+
+      ---------------
+      -- Skip_Char --
+      ---------------
+
+      procedure Skip_Char (S : in out Source_Ptr) is
+      begin
+         S := S + 1;
+      end Skip_Char;
+
+      --  Local variables
+
       SI  : constant Source_File_Index := Get_Source_File_Index (Sloc (N));
       SF  : constant Source_Ptr        := Source_First (SI);
       SL  : constant Source_Ptr        := Source_Last (SI);
@@ -2001,6 +2015,8 @@ package body Errout is
       F   : Node_Id;
       S   : Source_Ptr;
 
+   --  Start of processing for Last_Sloc
+
    begin
       F := Last_Node (N);
       S := Sloc (F);
@@ -2035,7 +2051,7 @@ package body Errout is
             while S < SL
               and then Src (S + 1) in '0' .. '9' | '_'
             loop
-               S := S + 1;
+               Skip_Char (S);
             end loop;
 
             --  Skip past #based_numeral#, if present
@@ -2043,30 +2059,36 @@ package body Errout is
             if S < SL
               and then Src (S + 1) = '#'
             then
-               S := S + 1;
+               Skip_Char (S);
 
                while S < SL
                  and then
                    Src (S + 1) in '0' .. '9' | 'a' .. 'f' | 'A' .. 'F' | '_'
                loop
-                  S := S + 1;
+                  Skip_Char (S);
                end loop;
 
-               pragma Assert (S < SL and then Src (S + 1) = '#');
-
-               S := S + 1;
+               if S < SL
+                 and then Src (S + 1) = '#'
+               then
+                  Skip_Char (S);
+               end if;
             end if;
 
             --  Skip past exponent, if present
 
-            if S < SL + 1
+            if S < SL
               and then Src (S + 1) in 'e' | 'E'
             then
+               Skip_Char (S);
+
                --  For positive exponents the plus sign is optional, but we
                --  can simply skip past both plus and minus.
 
-               if Src (S + 2) in '+' | '-' then
-                  S := S + 1;
+               if S < SL
+                 and then Src (S + 1) in '+' | '-'
+               then
+                  Skip_Char (S);
                end if;
 
                --  Skip past the numeral part
@@ -2074,7 +2096,7 @@ package body Errout is
                while S < SL
                  and then Src (S + 1) in '0' .. '9' | '_'
                loop
-                  S := S + 1;
+                  Skip_Char (S);
                end loop;
             end if;
 
@@ -2085,55 +2107,66 @@ package body Errout is
             while S < SL
               and then Src (S + 1) in '0' .. '9' | '_'
             loop
-               S := S + 1;
+               Skip_Char (S);
             end loop;
 
             if S < SL then
+
+               --  Skip the dot and continue with a decimal literal
+
                if Src (S + 1) = '.' then
+                  Skip_Char (S);
+
                   while S < SL
                     and then Src (S + 1) in '0' .. '9' | '_'
                   loop
-                     S := S + 1;
+                     Skip_Char (S);
                   end loop;
-               else
-                  pragma Assert (Src (S + 1) = '#');
 
-                  S := S + 1;
+               --  Skip the hash and continue with a based literal
+
+               elsif Src (S + 1) = '#' then
+                  Skip_Char (S);
 
                   while S < SL
                     and then
                       Src (S + 1) in '0' .. '9' | 'a' .. 'f' | 'A' .. 'F' | '_'
                   loop
-                     S := S + 1;
+                     Skip_Char (S);
                   end loop;
 
-                  pragma Assert (S < SL and then Src (S + 1) = '.');
-
-                  S := S + 1;
+                  if S < SL
+                    and then Src (S + 1) = '.'
+                  then
+                     Skip_Char (S);
+                  end if;
 
                   while S < SL
                     and then
                       Src (S + 1) in '0' .. '9' | 'a' .. 'f' | 'A' .. 'F' | '_'
                   loop
-                     S := S + 1;
+                     Skip_Char (S);
                   end loop;
 
-                  pragma Assert (S < SL and then Src (S + 1) = '#');
-
-                  S := S + 1;
+                  if S < SL
+                    and then Src (S + 1) = '#'
+                  then
+                     Skip_Char (S);
+                  end if;
                end if;
             end if;
 
             --  Skip past exponent, if present
 
-            if S < SL + 1
+            if S < SL
               and then Src (S + 1) in 'e' | 'E'
             then
+               Skip_Char (S);
                --  For positive exponents the plus sign is optional, but we
                --  can simply skip past both plus and minus.
 
-               if Src (S + 2) in '+' | '-' then
-                  S := S + 1;
+               if Src (S + 1) in '+' | '-' then
+                  Skip_Char (S);
                end if;
 
                --  Skip past the numeral part
@@ -2141,7 +2174,7 @@ package body Errout is
                while S < SL
                  and then Src (S + 1) in '0' .. '9' | '_'
                loop
-                  S := S + 1;
+                  Skip_Char (S);
                end loop;
             end if;
 
@@ -2153,7 +2186,7 @@ package body Errout is
                 in
               '0' .. '9' | 'a' .. 'z' | 'A' .. 'Z' | '_'
             loop
-               S := S + 1;
+               Skip_Char (S);
             end loop;
       end case;