是什么导致了这个 Ada 编译错误“歧义字符文字”？

Question

我有这个 Ada 代码。

with Ada.Text_IO; 
use Ada.Text_IO;

procedure for_Loop is
begin
    for Counter in 'A'..'Z' loop
        Put(Counter);   
    end loop;
    New_Line;
end for_Loop;

Ada 编译器 (gnatmake) 输出这些错误消息。

gcc -c for_loop.adb
for_loop.adb:6:24: ambiguous character literal
for_loop.adb:6:24: possible interpretation: Character
for_loop.adb:6:24: possible interpretation: Wide_Character
for_loop.adb:6:24: possible interpretation: Wide_Wide_Character
gnatmake: "for_loop.adb" compilation error

代码有什么问题？

Answer 1

从这篇文章：

问题是“A”和“Z”可能来自 Character 或 Wide_Character。最简单的修正是使类型显式；例如：对于字符范围内的字符 'A' .. 'Z' 循环 ... 结束循环；

with Ada.Text_IO; 
use Ada.Text_IO;

procedure for_Loop is
begin
    for Counter in Character range 'A'..'Z' loop
        Put(Counter);   
    end loop;
    New_Line;
end for_Loop;

这是输出：

ABCDEFGHIJKLMNOPQRSTUVWXYZ