> > Can someone please remind me in which repository I can find the GCC
> > prerequisites doc sources?
>
> Answering my own question: found it under gcc/doc/install.texi
>
> Working on it...
Just installed the following change on trunk, thanks again for your feedback!
2019-09-05 Arnaud Charlet <char...@adacore.com>
* doc/install.texi: Update and clarify requirements to build GNAT.
Index: doc/install.texi
===================================================================
--- doc/install.texi (revision 275399)
+++ doc/install.texi (working copy)
@@ -270,13 +270,35 @@
@option{--disable-multilib}. Otherwise, you may encounter an error such as
@samp{fatal error: gnu/stubs-32.h: No such file}
-@item GNAT
+@item @anchor{GNAT-prerequisite}GNAT
-In order to build the Ada compiler (GNAT) you must already have GNAT
-installed because portions of the Ada frontend are written in Ada (with
-GNAT extensions.) Refer to the Ada installation instructions for more
-specific information.
+In order to build GNAT, the Ada compiler, you need a working GNAT
+compiler (GCC version 4.7 or later).
+This includes GNAT tools such as @command{gnatmake} and
+@command{gnatlink}, since the Ada front end is written in Ada and
+uses some GNAT-specific extensions.
+
+In order to build a cross compiler, it is strongly recommended to install
+the new compiler as native first, and then use it to build the cross
+compiler. Other native compiler versions may work but this is not guaranteed
and
+will typically fail with hard to understand compilation errors during the
+build.
+
+Similarly, it is strongly recommended to use an older version of GNAT to build
+GNAT. More recent versions of GNAT than the version built are not guaranteed
+to work and will often fail during the build with compilation errors.
+
+Note that @command{configure} does not test whether the GNAT installation works
+and has a sufficiently recent version; if too old a GNAT version is
+installed and @option{--enable-languages=ada} is used, the build will fail.
+
+@env{ADA_INCLUDE_PATH} and @env{ADA_OBJECT_PATH} environment variables
+must not be set when building the Ada compiler, the Ada tools, or the
+Ada runtime libraries. You can check that your build environment is clean
+by verifying that @samp{gnatls -v} lists only one explicit path in each
+section.
+
@item A ``working'' POSIX compatible shell, or GNU bash
Necessary when running @command{configure} because some
@@ -2705,27 +2727,8 @@
@section Building the Ada compiler
-In order to build GNAT, the Ada compiler, you need a working GNAT
-compiler (GCC version 4.0 or later).
-This includes GNAT tools such as @command{gnatmake} and
-@command{gnatlink}, since the Ada front end is written in Ada and
-uses some GNAT-specific extensions.
+See @ref{GNAT-prerequisite}.
-In order to build a cross compiler, it is suggested to install
-the new compiler as native first, and then use it to build the cross
-compiler.
-
-@command{configure} does not test whether the GNAT installation works
-and has a sufficiently recent version; if too old a GNAT version is
-installed, the build will fail unless @option{--enable-languages} is
-used to disable building the Ada front end.
-
-@env{ADA_INCLUDE_PATH} and @env{ADA_OBJECT_PATH} environment variables
-must not be set when building the Ada compiler, the Ada tools, or the
-Ada runtime libraries. You can check that your build environment is clean
-by verifying that @samp{gnatls -v} lists only one explicit path in each
-section.
-
@section Building with profile feedback
It is possible to use profile feedback to optimize the compiler itself. This
