libghostty-vt: fix pkg-config libdir/includedir under split install

`pkgConfigFiles` in GhosttyLibVt.zig was emitting
`libdir=${prefix}/lib` and `includedir=${prefix}/include`, interpolating
a single install prefix for both the header and library locations. When
a packager installs libghostty-vt with the header tree rooted in one
place and the shared library in another (e.g. Nix multi-output
derivations splitting `$out` for runtime and `$dev` for development
artifacts), the interpolated libdir points at the wrong directory and
pkg-config-built consumers fail at runtime with

    libghostty-vt.so.<N>: cannot open shared object file

because the SONAME-versioned library does not actually live next to
`prefix`.

Resolve `libdir` and `includedir` to absolute paths via
`b.getInstallPath(.lib, "")` and `b.getInstallPath(.header, "")`, which
honor `--prefix-lib-dir` and `--prefix-include-dir` from zig's install
options. Single-prefix installs produce the same output as before;
split-prefix installs now embed the real, resolved locations into
libghostty-vt.pc without any downstream fixup.

The Nix package takes advantage of this by installing headers directly
into the `dev` output with `--prefix-include-dir`, which lets us drop
the entire postInstall dance (`mv $out/include $dev`, `rm $out/lib/libghostty-vt.so`
plus the `ln -sf` into `$dev/lib`, and the equivalent darwin unversioned
dylib relocation) and the postFixup that used to rewrite the .pc files.
libghostty-vt.a now stays alongside the shared library in `$out/lib`
so the shared and static .pc files share a single correct libdir,
eliminating the need for per-variant postFixup rewriting.

Removes the `-Wl,-rpath,"${finalAttrs.finalPackage}/lib"` workaround
from the `build-with-shared` and `build-example-c-vt-build-info`
passthru tests; they now prove that pkg-config alone is sufficient to
produce a binary whose dynamic loader can find libghostty-vt.so.<N>
at runtime.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: domenkozar

nix/libghostty-vt.nix

@@ -69,6 +69,14 @@ stdenv.mkDerivation (finalAttrs: {
     "-Dapp-runtime=none"
     "-Demit-lib-vt=true"
     "-Dsimd=${lib.boolToString simd}"
+    # Install headers directly into the `dev` output instead of letting
+    # them land in $out/include and relying on nixpkgs's multi-output
+    # fixup to relocate them. Because zig's pkg-config generator now
+    # records the resolved include path in libghostty-vt.pc, installing
+    # straight to $dev/include means the emitted `includedir=` is
+    # already correct -- no postFixup rewrite needed.
+    "--prefix-include-dir"
+    "${placeholder "dev"}/include"
   ];
   zigCheckFlags = finalAttrs.zigBuildFlags ++ ["test-lib-vt"];
 
@@ -77,61 +85,20 @@ stdenv.mkDerivation (finalAttrs: {
     "dev"
   ];
 
-  postInstall =
-    ''
-      mkdir -p "$dev/lib"
-      mv "$out/lib/libghostty-vt.a" "$dev/lib"
-      mv "$out/include" "$dev"
-      mv "$out/share" "$dev"
-    ''
-    + lib.optionalString stdenv.hostPlatform.isLinux ''
-      rm "$out/lib/libghostty-vt.so"
-      ln -sf "$out/lib/libghostty-vt.so.${lib.versions.major finalAttrs.version}"  "$dev/lib/libghostty-vt.so"
-    ''
-    + lib.optionalString stdenv.hostPlatform.isDarwin ''
-      # Zig's darwin install emits a versioned `libghostty-vt.<ver>.dylib`
-      # plus an unversioned `libghostty-vt.dylib` symlink in $out/lib.
-      # We want the build-time unversioned symlink to live in $dev so
-      # consumers can link via `-lghostty-vt` without pulling $out into
-      # their dev closure; remove $out's symlink and recreate an absolute
-      # one in $dev pointing at the versioned file in $out.
-      real=
-      for f in "$out/lib"/libghostty-vt*.dylib; do
-        if [ -e "$f" ] && [ ! -L "$f" ]; then
-          real="$f"
-          break
-        fi
-      done
-      if [ -z "$real" ]; then
-        echo "libghostty-vt: no versioned dylib found in $out/lib" >&2
-        ls -la "$out/lib" >&2
-        exit 1
-      fi
-      rm -f "$out/lib/libghostty-vt.dylib"
-      ln -sf "$real" "$dev/lib/libghostty-vt.dylib"
-    '';
-
-  postFixup = ''
-    substituteInPlace "$dev/share/pkgconfig/libghostty-vt.pc" \
-      --replace-fail "$out" "$dev"
-    substituteInPlace "$dev/share/pkgconfig/libghostty-vt-static.pc" \
-      --replace-fail "$out" "$dev"
-  '';
-
   passthru.tests = {
     sanity-check = let
       version = "${lib.versions.major finalAttrs.version}.${lib.versions.minor finalAttrs.version}.${lib.versions.patch finalAttrs.version}";
     in
       runCommand "sanity-check" {} (builtins.concatStringsSep "\n" [
         ''
           ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage}/lib/libghostty-vt.so.${version}" | grep -q 'T ghostty_terminal_new'
-          ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage.dev}/lib/libghostty-vt.a" | grep -q 'T ghostty_terminal_new'
+          ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage}/lib/libghostty-vt.a" | grep -q 'T ghostty_terminal_new'
         ''
         (
           lib.optionalString simd
           ''
-            ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage.dev}/lib/libghostty-vt.a" | grep -q 'T .*simdutf'
-            ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage.dev}/lib/libghostty-vt.a" | grep -q 'T .*3hwy'
+            ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage}/lib/libghostty-vt.a" | grep -q 'T .*simdutf'
+            ${lib.getExe' stdenv.cc "nm"} "${finalAttrs.finalPackage}/lib/libghostty-vt.a" | grep -q 'T .*3hwy'
           ''
         )
         ''
@@ -148,7 +115,7 @@ stdenv.mkDerivation (finalAttrs: {
         export PKG_CONFIG_PATH="${finalAttrs.finalPackage.dev}/share/pkgconfig"
 
         pkg-config --libs --static libghostty-vt | grep -q -- '-lghostty-vt'
-        pkg-config --libs --static libghostty-vt-static | grep -q -- '${finalAttrs.finalPackage.dev}/lib/libghostty-vt.a'
+        pkg-config --libs --static libghostty-vt-static | grep -q -- '${finalAttrs.finalPackage}/lib/libghostty-vt.a'
 
         touch "$out"
       '';
@@ -162,8 +129,7 @@ stdenv.mkDerivation (finalAttrs: {
         runHook preBuildHooks
 
         cc -o test test_libghostty_vt.c \
-          ''$(pkg-config --cflags --libs libghostty-vt) \
-          -Wl,-rpath,"${finalAttrs.finalPackage}/lib"
+          ''$(pkg-config --cflags --libs libghostty-vt)
 
         runHook postBuildHooks
       '';
@@ -241,8 +207,7 @@ stdenv.mkDerivation (finalAttrs: {
         runHook preBuildHooks
 
         cc -o test main.c \
-          ''$(pkg-config --cflags --libs libghostty-vt) \
-          -Wl,-rpath,"${finalAttrs.finalPackage}/lib"
+          ''$(pkg-config --cflags --libs libghostty-vt)
 
         runHook postBuildHooks
       '';

src/build/GhosttyLibVt.zig

@@ -371,11 +371,25 @@ fn pkgConfigFiles(
     const libs_private = libsPrivate(zig);
     const requires_private = requiresPrivate(b);
 
+    // Resolve `includedir` and `libdir` to absolute paths instead of
+    // interpolating `${prefix}/include` and `${prefix}/lib`. When a packager
+    // installs libghostty-vt with split prefixes (e.g. Nix multi-output
+    // derivations that put headers in a `-dev` output and runtime libraries
+    // in the default output), `${prefix}/lib` points at the wrong directory
+    // and pkg-config-built consumers fail at runtime with
+    //   libghostty-vt.so.<N>: cannot open shared object file
+    // because the SONAME-versioned library doesn't live next to `prefix`.
+    // Honoring `--prefix-lib-dir` / `--prefix-include-dir` by asking zig for
+    // the resolved install path keeps the default single-prefix behavior
+    // identical and additionally makes split-prefix installs correct.
+    const includedir = b.getInstallPath(.header, "");
+    const libdir = b.getInstallPath(.lib, "");
+
     return .{
         .shared = wf.add("libghostty-vt.pc", b.fmt(
             \\prefix={s}
-            \\includedir=${{prefix}}/include
-            \\libdir=${{prefix}}/lib
+            \\includedir={s}
+            \\libdir={s}
             \\
             \\Name: libghostty-vt
             \\URL: https://github.com/ghostty-org/ghostty
@@ -385,11 +399,18 @@ fn pkgConfigFiles(
             \\Libs: -L${{libdir}} -lghostty-vt
             \\Libs.private: {s}
             \\Requires.private: {s}
-        , .{ b.install_prefix, zig.version, libs_private, requires_private })),
+        , .{
+            b.install_prefix,
+            includedir,
+            libdir,
+            zig.version,
+            libs_private,
+            requires_private,
+        })),
         .static = wf.add("libghostty-vt-static.pc", b.fmt(
             \\prefix={s}
-            \\includedir=${{prefix}}/include
-            \\libdir=${{prefix}}/lib
+            \\includedir={s}
+            \\libdir={s}
             \\
             \\Name: libghostty-vt-static
             \\URL: https://github.com/ghostty-org/ghostty
@@ -401,6 +422,8 @@ fn pkgConfigFiles(
             \\Requires.private: {s}
         , .{
             b.install_prefix,
+            includedir,
+            libdir,
             zig.version,
             staticLibraryName(os_tag),
             libs_private,