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From: Blady <p.p11@orange.fr>
Newsgroups: comp.lang.ada
Subject: Type inference with String_Literal.
Date: Sat, 26 Dec 2020 10:12:53 +0100
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Hello,

In the following test program, line 16 the string literal is correctly 
inferred to Wide_Wide_String and line 17 the string literal is correctly 
inferred to My_Type1 as aspect String_Literal is defined line 7 for this 
type.
But line 18, GNAT reports a type match error in a "if expression" with 
string literals.
String literal in the "if expression" has to qualified by My_Type1 as in 
line 20:

     1. with Ada.Wide_Wide_Text_IO;
      2. procedure Test_20201225_str_lit is
      3.
      4.    type My_Type1 (Length : Natural) is record
      5.       Value : Wide_Wide_String (1 .. Length);
      6.    end record with
      7.       String_Literal => From_String1;
      8.    function From_String1 (Value : Wide_Wide_String) return 
My_Type1 is ((Length => Value'Length, Value => Value));
      9.    procedure Print1 (Self : My_Type1) is
     10.    begin
     11.       Ada.Wide_Wide_Text_IO.Put_Line (Self.Value);
     12.    end Print1;
     13.
     14.    function Test return Boolean is (True);
     15.
     16.    S : Wide_Wide_String := (if Test then "test0" else "");
     17.    MV0 : My_Type1 := "test0";
     18.    MV1 : My_Type1 := (if Test then "test1" else "");
                               |
         >>> expected type "My_Type1" defined at line 4
         >>> found a string type

     19.    MV2 : My_Type1 := My_Type1'(if Test then "test2" else "");
                                        |
         >>> expected type "My_Type1" defined at line 4
         >>> found a string type

     20.    MV3 : My_Type1 := (if Test then My_Type1'("test3") else "");
     21.
     22. begin
     23.    Print1 ("Test ""string""");
     24.    Print1 ("88");
     25.    Print1 (MV1);
     26.    Print1 (MV2);
     27. end Test_20201225_str_lit;

Shouldn't GNAT set the type My_Type1 for the string literal in line 18 
as it does line 17?

Thanks, Pascal.