From a6f9af354a9cd2c7b06ebe9c5b4958d527291810 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Fri, 21 Aug 2020 21:19:02 +0100
Subject: [PATCH] stdlib/fedora.gl: Simpler quicker way to work out
 dependencies.

This removes the O(n^3) loop.
---
 stdlib/fedora.gl | 26 ++++++++------------------
 1 file changed, 8 insertions(+), 18 deletions(-)

diff --git a/stdlib/fedora.gl b/stdlib/fedora.gl
index 8bcc09a..999c55f 100644
--- a/stdlib/fedora.gl
+++ b/stdlib/fedora.gl
@@ -143,26 +143,16 @@ pure function fedora-source-dependencies (pkg) returning strings = @{
 
     # We will require the mapping of all source packages to the
     # list of binary packages they build, so work this out in advance.
-    declare -A binpkgs
+    declare -A bin2src
     for p in %fedora-source-packages; do
-        binpkgs[$p]="$(
-            rpmspec -q --provides %fedora-dir/$p/%fedora-branch/$p.spec 2>/dev/null |
-            awk '{print $1}'
-        )"
+        for b in $(rpmspec -q --provides %fedora-dir/$p/%fedora-branch/$p.spec 2>/dev/null | awk '{print $1}'); do
+            bin2src[$b]=$p
+        done
     done
 
-    for r in $(rpmspec -q --buildrequires $specfile 2>/dev/null |
+    for b in $(rpmspec -q --buildrequires $specfile 2>/dev/null |
                awk '{print $1}'); do
-        # Now we examine each *other* source package to see
-        # if any will create this dependency when they build.
-        for p in %fedora-source-packages; do
-            if [ "$p" != %pkg ]; then
-                for f in ${binpkgs[$p]}; do
-                    if [ "$f" = "$r" ]; then
-                        echo "$p"
-                    fi
-                done
-            fi
-        done
-    done | sort -u
+        # Find the source package that produces these binary requirements.
+        echo ${bin2src[$b]}
+    done | grep -v '^$' | sort -u
 }
-- 
1.8.3.1