Does hyphen have special meaning in GPR project files?

Jesper-Quorning · January 10, 2023, 6:37pm

Does hyphen (-) have special meaning like in GNAT Ada source files ?

ksson · January 11, 2023, 2:17am

The title of your post mentions GPR project files, but your text says “GNAT Ada source files”. But in any case, the answer is “yes”. In Ada, “-” has the special meaning to be the binary or unary “minus” operator. Also, you can’t use “-” in identifiers, to avoid confusion between an identifier A-B and the expression A - B. Also, double hyphen -- is used for comments:

--  This is a comment

For GPR files I believe it’s identical, you can’t use hyphen in identifiers, and the syntax for comments is the same.

simonjwright · January 11, 2023, 9:14am

In case you mean “in GPR project file names”, then I think the answer is no; indeed, if you put a hyphen in a project file name, gprbuild will just complain that the name and the file name don’t match (and you can’t put a hyphen in the project name).

Fabien.C · January 11, 2023, 9:53am

Actually

Like Ada units, GPR project can have child projects: 2. GNAT Project Manager — GPR Tools User's Guide 24.0w documentation

In which case you use a dash in the filename, like for Ada units. See here for example:

github.com

AdaCore/gpr/blob/28af85691fba8aa83ea71deb3ff90b5546597f96/bindings/c/gpr2-c.gpr

--
--  Copyright (C) 2019-2023, AdaCore
--
--  SPDX-License-Identifier: Apache-2.0
--

with "gpr2";

library project GPR2.C is

   type Build_Type is ("debug", "release");
   Build : Build_Type := external ("GPR2_BUILD", "debug");

   Processors := external ("PROCESSORS", "0");

   for Languages use ("Ada");
   for Source_Dirs use ("src");
   for Library_Name use "gpr2c";

   for Object_Dir use "build/" & Build & "/obj";

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ebriot · January 13, 2023, 8:11am

I was part of the initial design team for the project files, and I did not even know we could have child projects !
They do not seem to bring any semantics beside grouping related projects, which already is kind of nice. I might make changes in our code base to use them.

Jesper-Quorning · February 5, 2023, 2:27am

It might be like Ada 83; You can get a long way with nested packages; I found out eventually…!