install.texi: Mention Rust requirement for building gccrs

Addresses PR#117869

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117869

gcc/ChangeLog:

	* doc/install.texi: Add requirements for building gccrs.

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index d8414fdbdc94d3429948426ee119573d219b6ab3..c6ef78e9491ef26d7d45e1c99a6e7dc7be6eef3b 100644 (file)
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -312,6 +312,12 @@ documentation including the target @code{SYSTEM} definition module.
 If Python3 is unavailable Modula-2 documentation will include a target
 independent version of the SYSTEM modules.
 
+@item @anchor{gccrs-prerequisite}gccrs
+
+The official Rust compiler and Rust build system (cargo) are required for
+building various parts of the gccrs frontend, until gccrs can compile them
+by itself. The minimum supported Rust version is 1.49.
+
 @item A ``working'' POSIX compatible shell, or GNU bash
 
 Necessary when running @command{configure} because some