From f9419291dbbfe38d9dfc3d28b9c1b5b7bb480d6c Mon Sep 17 00:00:00 2001
From: Janus Troelsen <janus@flipstone.com>
Date: Thu, 12 Nov 2026 12:42:34 -0600
Subject: [PATCH] Install binutils-gold for ghc < 9.6 on Linux

GHC < 9.6 bindists ship an hsc2hs wrapper with a hardcoded
"--lflag=-fuse-ld=gold". Since binutils 2.44 deprecated gold, Ubuntu
25.10 and later no longer include ld.gold in binutils, so hsc2hs fails
to link there. Install the separate binutils-gold package via apt-get
when ld.gold is missing.

This runs before the isInstalled check, so preinstalled or cached GHCs
are covered too. Failure to install only emits a warning.
---
 dist/index.js    | 34 ++++++++++++++++++++++++++++++++++
 lib/installer.js | 34 ++++++++++++++++++++++++++++++++++
 src/installer.ts | 44 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 112 insertions(+)

diff --git a/dist/index.js b/dist/index.js
index 9690917..61f652d 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -35124,6 +35124,19 @@ async function isInstalled(tool, version, os, arch) {
     return false;
 }
 async function installTool(tool, version, os, arch) {
+    // GHC < 9.6 bindists ship an hsc2hs wrapper with a hardcoded
+    // "--lflag=-fuse-ld=gold", so ld.gold has to be present whenever hsc2hs
+    // runs, even if GHC itself is already installed (preinstalled or cached).
+    // Hence, do this before the isInstalled check.
+    // “version” may not be a semantic version (e.g. “latest-nightly”),
+    // so guard “compareVersions” with “validate”.
+    if (os === 'linux' &&
+        tool === 'ghc' &&
+        (0, compare_versions_1.validate)(version) &&
+        (0, compare_versions_1.compareVersions)(version, '9.6') < 0 // meaning version < 9.6
+    ) {
+        await aptBinutilsGold();
+    }
     if (await isInstalled(tool, version, os, arch))
         return;
     warn(tool, version);
@@ -35241,6 +35254,27 @@ async function aptBuildEssential() {
     const returnCode = await exec(`sudo -- sh -c "apt-get update && apt-get -y install build-essential"`);
     return returnCode === 0;
 }
+async function aptBinutilsGold() {
+    // Up to ubuntu-24.04, ld.gold is part of binutils. Since binutils 2.44
+    // deprecated gold, ubuntu-25.10 and later ship it in a separate
+    // binutils-gold package instead.
+    if (await (0, io_1.which)('ld.gold', false)) {
+        core.debug('ld.gold is already installed');
+        return true;
+    }
+    if (!(await (0, io_1.which)('apt-get', false))) {
+        core.warning('ld.gold not found and apt-get is unavailable; hsc2hs of ghc < 9.6 may fail to link');
+        return false;
+    }
+    core.info(`Installing binutils-gold using apt-get (for ghc < 9.6)`);
+    // exec throws (instead of returning non-zero) if e.g. sudo is not
+    // available; this must not fail the action, as hsc2hs may not be needed.
+    const returnCode = await exec(`sudo -- sh -c "apt-get update && apt-get -y install binutils-gold"`).catch(() => -1);
+    if (returnCode !== 0) {
+        core.warning('Failed to install binutils-gold; hsc2hs of ghc < 9.6 may fail to link');
+    }
+    return returnCode === 0;
+}
 async function aptLibNCurses5() {
     core.info(`Installing libcurses5 and libtinfo5 using apt-get (for ghc < 8.3)`);
     // ubuntu-24.04 requires the specific source to install libncurses5 and libtinfo5,
diff --git a/lib/installer.js b/lib/installer.js
index e21a346..116208e 100644
--- a/lib/installer.js
+++ b/lib/installer.js
@@ -148,6 +148,19 @@ async function isInstalled(tool, version, os, arch) {
     return false;
 }
 async function installTool(tool, version, os, arch) {
+    // GHC < 9.6 bindists ship an hsc2hs wrapper with a hardcoded
+    // "--lflag=-fuse-ld=gold", so ld.gold has to be present whenever hsc2hs
+    // runs, even if GHC itself is already installed (preinstalled or cached).
+    // Hence, do this before the isInstalled check.
+    // “version” may not be a semantic version (e.g. “latest-nightly”),
+    // so guard “compareVersions” with “validate”.
+    if (os === 'linux' &&
+        tool === 'ghc' &&
+        (0, compare_versions_1.validate)(version) &&
+        (0, compare_versions_1.compareVersions)(version, '9.6') < 0 // meaning version < 9.6
+    ) {
+        await aptBinutilsGold();
+    }
     if (await isInstalled(tool, version, os, arch))
         return;
     warn(tool, version);
@@ -265,6 +278,27 @@ async function aptBuildEssential() {
     const returnCode = await exec(`sudo -- sh -c "apt-get update && apt-get -y install build-essential"`);
     return returnCode === 0;
 }
+async function aptBinutilsGold() {
+    // Up to ubuntu-24.04, ld.gold is part of binutils. Since binutils 2.44
+    // deprecated gold, ubuntu-25.10 and later ship it in a separate
+    // binutils-gold package instead.
+    if (await (0, io_1.which)('ld.gold', false)) {
+        core.debug('ld.gold is already installed');
+        return true;
+    }
+    if (!(await (0, io_1.which)('apt-get', false))) {
+        core.warning('ld.gold not found and apt-get is unavailable; hsc2hs of ghc < 9.6 may fail to link');
+        return false;
+    }
+    core.info(`Installing binutils-gold using apt-get (for ghc < 9.6)`);
+    // exec throws (instead of returning non-zero) if e.g. sudo is not
+    // available; this must not fail the action, as hsc2hs may not be needed.
+    const returnCode = await exec(`sudo -- sh -c "apt-get update && apt-get -y install binutils-gold"`).catch(() => -1);
+    if (returnCode !== 0) {
+        core.warning('Failed to install binutils-gold; hsc2hs of ghc < 9.6 may fail to link');
+    }
+    return returnCode === 0;
+}
 async function aptLibNCurses5() {
     core.info(`Installing libcurses5 and libtinfo5 using apt-get (for ghc < 8.3)`);
     // ubuntu-24.04 requires the specific source to install libncurses5 and libtinfo5,
diff --git a/src/installer.ts b/src/installer.ts
index 1295598..a3a0cf5 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -146,6 +146,21 @@ export async function installTool(
   os: OS,
   arch: Arch
 ): Promise<void> {
+  // GHC < 9.6 bindists ship an hsc2hs wrapper with a hardcoded
+  // "--lflag=-fuse-ld=gold", so ld.gold has to be present whenever hsc2hs
+  // runs, even if GHC itself is already installed (preinstalled or cached).
+  // Hence, do this before the isInstalled check.
+  // “version” may not be a semantic version (e.g. “latest-nightly”),
+  // so guard “compareVersions” with “validate”.
+  if (
+    os === 'linux' &&
+    tool === 'ghc' &&
+    validate(version) &&
+    compareVersions(version, '9.6') < 0 // meaning version < 9.6
+  ) {
+    await aptBinutilsGold();
+  }
+
   if (await isInstalled(tool, version, os, arch)) return;
   warn(tool, version);
 
@@ -281,6 +296,35 @@ async function aptBuildEssential(): Promise<boolean> {
   return returnCode === 0;
 }
 
+async function aptBinutilsGold(): Promise<boolean> {
+  // Up to ubuntu-24.04, ld.gold is part of binutils. Since binutils 2.44
+  // deprecated gold, ubuntu-25.10 and later ship it in a separate
+  // binutils-gold package instead.
+  if (await which('ld.gold', false)) {
+    core.debug('ld.gold is already installed');
+    return true;
+  }
+  if (!(await which('apt-get', false))) {
+    core.warning(
+      'ld.gold not found and apt-get is unavailable; hsc2hs of ghc < 9.6 may fail to link'
+    );
+    return false;
+  }
+
+  core.info(`Installing binutils-gold using apt-get (for ghc < 9.6)`);
+  // exec throws (instead of returning non-zero) if e.g. sudo is not
+  // available; this must not fail the action, as hsc2hs may not be needed.
+  const returnCode = await exec(
+    `sudo -- sh -c "apt-get update && apt-get -y install binutils-gold"`
+  ).catch(() => -1);
+  if (returnCode !== 0) {
+    core.warning(
+      'Failed to install binutils-gold; hsc2hs of ghc < 9.6 may fail to link'
+    );
+  }
+  return returnCode === 0;
+}
+
 async function aptLibNCurses5(): Promise<boolean> {
   core.info(
     `Installing libcurses5 and libtinfo5 using apt-get (for ghc < 8.3)`