[lmi-commits] [lmi] master 3e044f3 1/2: Import a script from branch odd/multiarch

[Greg Chicares]

branch: master
commit 3e044f3315635ec7b0ddb37ea1a47c152c7b7030
Author: Gregory W. Chicares <address@hidden>
Commit: Gregory W. Chicares <address@hidden>

    Import a script from branch odd/multiarch
    
    As of this moment, odd/multiarch is almost identical to earlier
    revision caf6f5506 on lmi trunk:
      $git merge-base master origin/odd/multiarch
      caf6f55067448e3ddf9c30b7be5bb7f09fdcfa15
      $git diff caf6f5506..origin/odd/multiarch
    Importing this script is the first step toward merging the branch
    (manually, with careful editing) into trunk.
---
 set_toolchain.sh | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 167 insertions(+)

diff --git a/set_toolchain.sh b/set_toolchain.sh
new file mode 100755
index 0000000..54b7caa
--- /dev/null
+++ b/set_toolchain.sh
@@ -0,0 +1,167 @@
+#!/bin/sh this-script-must-be-sourced-not-run
+
+# Set $PATH, $WINEPATH, and $PERFORM based on $LMI_COMPILER and $LMI_TRIPLET.
+
+# Copyright (C) 2019 Gregory W. Chicares.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+#
+# http://savannah.nongnu.org/projects/lmi
+# email: <address@hidden>
+# snail: Chicares, 186 Belle Woods Drive, Glastonbury CT 06033, USA
+
+# Invoke as ". ./set_toolchain.sh" without the quotes.
+#
+# $LMI_COMPILER and $LMI_TRIPLET can be overridden at the command
+# line, e.g.:
+#
+#   export LMI_COMPILER
+#   export LMI_TRIPLET
+#   LMI_COMPILER=gcc ; LMI_TRIPLET=i686-w64-mingw32 ; . ./set_toolchain.sh
+#   LMI_COMPILER=gcc ; LMI_TRIPLET=x86_64-w64-mingw32 ; . ./set_toolchain.sh
+#
+# where the 'export' commands need be run only once, presumably in a
+# shell startup file.
+#
+# Implemented as a function that runs and then erases itself, so that
+# sourcing this script changes the environment only as intended. This
+# depends on 'local', which isn't yet POSIX, though there's a proposal
+# to add it:
+#   http://austingroupbugs.net/view.php?id=767
+# 'dash' and 'ash' already have 'local', so, while it's not yet POSIX,
+# it's used here, and its 'shellcheck' warning is disabled:
+# shellcheck disable=SC2039
+
+# Unimplemented alternative: Variables such as $prefix could be made
+# similarly overridable, along with other directories--perhaps even
+# platform-specific ones like $mingw_bin_dir.
+
+# Unimplemented alternative: use symlinks, e.g:
+#   ln --symbolic --force --no-dereference \
+#   /opt/lmi/"${LMI_COMPILER}_${LMI_TRIPLET}"/bin /opt/lmi/bin
+# and likewise for all other directories. Depending on symlinks
+# didn't seem like a good idea.
+
+# This alternative for future consideration trades some complexity of
+# implementation for mitigation of confusion and convenience of use.
+#
+# To cross-build autotoolized libraries, configure with:
+#   --host=$LMI_TRIPLET
+#   --exec_prefix=$prefix/$LMI_TOOLCHAIN
+# where
+#   LMI_TOOLCHAIN=${LMI_COMPILER}_${LMI_TRIPLET}
+#
+# Supported values:
+#   LMI_COMPILER : gcc, clang
+#   LMI_TRIPLET  : i686-w64-mingw32, x86_64-w64-mingw32, x86_64-pc-linux-gnu
+#
+# Examples:
+#
+#  LMI_TOOLCHAIN  LMI_COMPILER  ----------LMI_TRIPLET----------
+#                               cpu     -vendor -[kernel-]system
+#
+#      gcc_msw32       gcc      i686    -w64            -mingw32
+#      gcc_msw64       gcc      x86_64  -w64            -mingw32
+#    clang_gnu64      clang     x86_64  -pc     -linux  -gnu
+#
+# Rationale: Triplets are required for selecting cross compilers. GNU
+# triplets are in widespread use, although debian uses its own:
+#   https://wiki.debian.org/Multiarch/Tuples#Why_not_use_GNU_triplets.3F
+# The main reason for lmi to establish its own is that the official
+# triplets for msw are so poor. For example, "i686-w64-mingw32" has
+# substrings "64" and "32". Both seem to specify the CPU's word size
+# (contradicting each other), but actually neither does--the word size
+# is determined by the "i686" field. See:
+#   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=622276
+
+foo()
+{
+local   lmi_build_type
+        lmi_build_type=$(/usr/share/libtool/build-aux/config.guess)
+
+local      prefix="/opt/lmi"
+local exec_prefix="$prefix/${LMI_COMPILER}_${LMI_TRIPLET}"
+local localbindir="$exec_prefix"/local/bin
+local locallibdir="$exec_prefix"/local/lib
+local  winebindir="$prefix"/third_party/bin
+
+# Running a command like this many times:
+#   export PATH="$localbindir":"$locallibdir":"$PATH"
+# would cause $PATH to grow without bound.
+#
+# The default non-lmi portion of this $PATH is, as always, debatable;
+# debian's default in '/etc/login.defs' adds silly 'games' directories
+# but omits '/usr/sbin' and '/sbin', for instance.
+
+minimal_path=${MINIMAL_PATH:-"/usr/bin:/bin:/usr/sbin:/sbin"}
+export PATH="$localbindir":"$locallibdir":"$minimal_path"
+
+# It is appropriate to unset $WINEPATH because no lmi script ever uses
+# it directly--it's used, implicitly, only by 'wine'. But $PERFORM is
+# used directly, so it's always exported, even if empty--though that's
+# probably just a matter of taste.
+
+unset -v WINEPATH
+export PERFORM
+
+# Are double quotes inside double quotes inside $() dubious? I.e.,
+#  " $( "is this string quoted?" ) "
+# Answer: yes, it is: everything inside '$()' is parsed separately.
+#   
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_03
+# [2.3/5] "The characters found from the beginning of the
+# substitution to its end, allowing for any recursion necessary
+# to recognize embedded constructs, shall be included unmodified
+# in the result token, including any embedded or enclosing
+# substitution operators or quotes. The token shall not be
+# delimited by the end of the substitution."
+#
+# 'winepath' doesn't DTRT with '/first/path:/second/path'--need to
+#   run it against each component, and separate results with ';', not ':'
+#
+case "$lmi_build_type" in
+    (*-*-linux*)
+        w0="$(winepath -w "$localbindir" | sed -e's/\\/\\\\/g')"
+        w1="$(winepath -w "$locallibdir" | sed -e's/\\/\\\\/g')"
+        w2="$(winepath -w "$winebindir"  | sed -e's/\\/\\\\/g')"
+        export WINEPATH="$w0;$w1;$w2"
+        export  PERFORM="wine"
+        ;;
+    (*) ;;
+esac
+}
+
+# This script is to be sourced, so it can't use a builtin command like
+# 'printf' here. Similarly, 'exit' would have a surprising effect.
+# Therefore, these precondition checks use 'echo' and 'return'.
+
+case "$LMI_COMPILER" in
+    (gcc) ;;
+    (*)
+        echo "Changed nothing because compiler '$LMI_COMPILER' is untested."
+        return 2;
+        ;;
+esac
+
+case "$LMI_TRIPLET" in
+    (i686-w64-mingw32)   ;;
+    (x86_64-w64-mingw32) ;;
+    (*)
+        echo "Changed nothing because host triplet '$LMI_TRIPLET' is untested."
+        return 3;
+        ;;
+esac
+
+foo
+
+unset -f foo