Append Homebrew custom prefix to search path (#1957)

This is needed to find other Python deps (e.g. libintl) in Homebrew if it has
nonstandard prefix (e.g. in Apple M1)

* Re-allow to search Homebrew for zlib everywhere

plugins/python-build/bin/python-build

@@ -773,10 +773,13 @@ build_package_standard_build() {
   local PACKAGE_CFLAGS="${package_var_name}_CFLAGS"
 
   if [ "$package_var_name" = "PYTHON" ]; then
+    use_homebrew || true
     use_tcltk || true
     use_homebrew_readline || use_freebsd_pkg || true
     if is_mac -ge 1014; then
       use_xcode_sdk_zlib || use_homebrew_zlib || true
+    else
+      use_homebrew_zlib || true
     fi
   fi
 
@@ -1325,6 +1328,19 @@ configured_with_package_dir() {
   return 1
 }
 
+use_homebrew() {
+  # unless Homebrew is at the default /usr/local, need to add its paths to
+  # compiler search to be able to use non-keg-only deps from there
+  if command -v brew &>/dev/null; then
+    local brew_prefix="$(brew --prefix 2>/dev/null || true)"
+    # /usr/local/lib:/usr/lib is the default library search path
+    if [[ -n $brew_prefix && $brew_prefix != "/usr" && $brew_prefix != "/usr/local" ]]; then
+      export CPPFLAGS="${CPPFLAGS:+${CPPFLAGS% } }-I${brew_prefix}/include"
+      export LDFLAGS="${LDFLAGS:+${LDFLAGS% } }-L${brew_prefix}/lib"
+    fi
+  fi
+}
+
 needs_yaml() {
   ! configured_with_package_dir "python" "yaml.h" &&
   ! use_homebrew_yaml

plugins/python-build/test/build.bats

@@ -62,10 +62,7 @@ assert_build_log() {
   cached_tarball "yaml-0.1.6"
   cached_tarball "Python-3.6.2"
 
-  # pyenv/pyenv#1026
-  stub uname false false
-
-  stub uname '-s : echo Linux' '-s : echo Linux'
+  for i in {1..4}; do stub uname '-s : echo Linux'; done
   stub brew false
   stub_make_install
   stub_make_install
@@ -92,10 +89,7 @@ OUT
   cached_tarball "yaml-0.1.6"
   cached_tarball "Python-3.6.2"
 
-  # pyenv/pyenv#1026
-  stub uname false false
-
-  stub uname '-s : echo Linux' '-s : echo Linux'
+  for i in {1..4}; do stub uname '-s : echo Linux'; done
   stub brew false
   stub_make_install
   stub_make_install
@@ -154,6 +148,34 @@ make install
 OUT
 }
 
+@test "homebrew with uncommon prefix is added to search path" {
+  cached_tarball "Python-3.6.2"
+
+  BREW_PREFIX="$TMP/homebrew-prefix"
+  mkdir -p "$BREW_PREFIX"
+
+  for i in {1..4}; do stub uname '-s : echo Darwin'; done
+  for i in {1..2}; do stub sw_vers '-productVersion : echo 1010'; done
+  stub brew "--prefix : echo '$BREW_PREFIX'" false
+  stub_make_install
+
+  run_inline_definition <<DEF
+install_package "Python-3.6.2" "http://python.org/ftp/python/3.6.2/Python-3.6.2.tar.gz"
+DEF
+  assert_success
+
+  unstub sw_vers
+  unstub uname
+  unstub make
+
+  assert_build_log <<OUT
+Python-3.6.2: CPPFLAGS="-I${TMP}/install/include -I$BREW_PREFIX/include" LDFLAGS="-L${TMP}/install/lib -L$BREW_PREFIX/lib"
+Python-3.6.2: --prefix=$INSTALL_ROOT --libdir=$INSTALL_ROOT/lib
+make -j 2
+make install
+OUT
+}
+
 @test "yaml is linked from Homebrew" {
   cached_tarball "Python-3.6.2"
 
@@ -162,7 +184,8 @@ OUT
 
   for i in {1..4}; do stub uname '-s : echo Darwin'; done
   for i in {1..2}; do stub sw_vers '-productVersion : echo 1010'; done
-  stub brew "--prefix libyaml : echo '$brew_libdir'" false false
+  stub brew "--prefix libyaml : echo '$brew_libdir'"
+  for i in {1..4}; do stub brew false; done
   stub_make_install
 
   install_fixture definitions/needs-yaml
@@ -186,11 +209,10 @@ OUT
 
   readline_libdir="$TMP/homebrew-readline"
   mkdir -p "$readline_libdir"
-
-  # pyenv/pyenv#1026
-  stub uname false false
-
-  stub brew false "--prefix readline : echo '$readline_libdir'"
+  stub uname false
+  for i in {1..2}; do stub brew false; done
+  stub brew "--prefix readline : echo '$readline_libdir'"
+  stub brew false
   stub_make_install
 
   run_inline_definition <<DEF
@@ -220,7 +242,7 @@ OUT
   # pyenv/pyenv#1026
   stub uname false false
 
-  stub brew false
+  for i in {1..3}; do stub brew false; done
   stub_make_install
 
   export PYTHON_CONFIGURE_OPTS="CPPFLAGS=-I$readline_libdir/include LDFLAGS=-L$readline_libdir/lib"
@@ -248,9 +270,9 @@ OUT
   echo "TCL_VERSION='$tcl_tk_version'" >>"$tcl_tk_libdir/lib/tclConfig.sh"
 
   stub uname false
-
-  for i in {1..2}; do stub brew "--prefix tcl-tk : echo '$tcl_tk_libdir'"; done
   stub brew false
+  for i in {1..2}; do stub brew "--prefix tcl-tk : echo '$tcl_tk_libdir'"; done
+  for i in {1..2}; do stub brew false; done
   stub_make_install
 
   run_inline_definition <<DEF
@@ -279,7 +301,7 @@ OUT
   # pyenv/pyenv#1026
   stub uname false false
 
-  stub brew false false
+  for i in {1..4}; do stub brew false; done
   stub_make_install
 
   export PYTHON_CONFIGURE_OPTS="--with-tcltk-libs='-L${TMP}/custom-tcl-tk/lib -ltcl$tcl_tk_version -ltk$tcl_tk_version'"

plugins/python-build/test/pyenv_ext.bats

@@ -314,7 +314,7 @@ EOS
 @test "enable custom unicode configuration" {
   cached_tarball "Python-3.6.2"
 
-  for i in {1..2}; do stub brew '* : false'; done
+  for i in {1..4}; do stub brew false; done
   for i in {1..3}; do stub uname '-s : echo Linux'; done
   stub "$MAKE" \
     " : echo \"$MAKE \$@\" >> build.log" \