Qt 6 host binaries have moved to QT_HOST_LIBEXECS in Qt 6.1+

[jlindgren90]

Describe the bug
meson fails to find the moc, rcc, and uic binaries from Qt 6.1+ because they have moved from QT_HOST_BINS to QT_HOST_LIBEXECS.

To Reproduce
meson.build:

project('test', 'c')
qt6 = import('qt6')
qt6.preprocess(qresources: 'test.qrc')

Run QMAKE=qmake6 meson build.
Partial output:

Run-time dependency qt6 (modules: Core) found: YES 6.2.2 (qmake)
Program /usr/lib/qt6/bin/moc found: NO
Program moc-qt6 found: NO
Program moc found: NO found 5.15.2 but need: '== 6.2.2' (/usr/bin/moc)
Program /usr/lib/qt6/bin/uic found: NO
Program uic-qt6 found: NO
Program uic found: NO found 5.15.2 but need: '== 6.2.2' (/usr/bin/uic)
Program /usr/lib/qt6/bin/rcc found: NO
Program rcc-qt6 found: NO
Program rcc found: NO found 5.15.2 but need: '== 6.2.2' (/usr/bin/rcc)
Program /usr/lib/qt6/bin/lrelease found: YES 6.2.2 (/usr/lib/qt6/bin/lrelease)

meson.build:3:4: ERROR: RCC sources specified and couldn't find rcc-qt6, please check your qt6 installation

Expected behavior
meson should find the rcc binary which is located at /usr/lib/qt6/rcc.

system parameters

• native build
• Arch Linux
• Python 3.10.1
• meson 0.60.3
• ninja 1.10.2

Proof-of-concept patch to add support for QT_HOST_LIBEXECS:

From 3dcdd69637ffba416e2e99fd812772b028dd0b83 Mon Sep 17 00:00:00 2001
From: John Lindgren <john@jlindgren.net>
Date: Sat, 8 Jan 2022 16:21:27 -0500
Subject: [PATCH] Add support for Qt 6.1+

Qt 6.1 moved the location of some binaries from QT_HOST_BINS to
QT_HOST_LIBEXECS as noted in the changelog:

c515ee178f Move build tools to libexec instead of the bin dir
- Tools that are called by the build system and are unlikely to be
called by the user are now installed to the libexec directory.

https://code.qt.io/cgit/qt/qtreleasenotes.git/tree/qt/6.1.0/release-note.txt

To compensate, meson now needs to look for moc, rcc, uic, etc. in
QT_HOST_LIBEXECS as well as QT_HOST_BINS.
---
 mesonbuild/dependencies/qt.py | 8 ++++++++
 mesonbuild/modules/qt.py      | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/mesonbuild/dependencies/qt.py b/mesonbuild/dependencies/qt.py
index 699f912c5..09140a85a 100644
--- a/mesonbuild/dependencies/qt.py
+++ b/mesonbuild/dependencies/qt.py
@@ -69,6 +69,12 @@ def get_qmake_host_bins(qvars: T.Dict[str, str]) -> str:
     return qvars['QT_INSTALL_BINS']
 
 
+def get_qmake_host_libexecs(qvars: T.Dict[str, str]) -> str:
+    if 'QT_HOST_LIBEXECS' in qvars:
+        return qvars['QT_HOST_LIBEXECS']
+    return qvars['QT_INSTALL_LIBEXECS']
+
+
 def _get_modules_lib_suffix(version: str, info: 'MachineInfo', is_debug: bool) -> str:
     """Get the module suffix based on platform and debug type."""
     suffix = ''
@@ -277,6 +283,7 @@ class QmakeQtDependency(_QtBase, ConfigToolDependency, metaclass=abc.ABCMeta):
         libdir = qvars['QT_INSTALL_LIBS']
         # Used by qt.compilers_detect()
         self.bindir = get_qmake_host_bins(qvars)
+        self.libexecdir = get_qmake_host_libexecs(qvars)
 
         # Use the buildtype by default, but look at the b_vscrt option if the
         # compiler supports it.
@@ -353,6 +360,7 @@ class QmakeQtDependency(_QtBase, ConfigToolDependency, metaclass=abc.ABCMeta):
             self.is_found = True
             # Used by self.compilers_detect()
             self.bindir = get_qmake_host_bins(qvars)
+            self.libexecdir = get_qmake_host_libexecs(qvars)
 
     def log_info(self) -> str:
         return 'qmake'
diff --git a/mesonbuild/modules/qt.py b/mesonbuild/modules/qt.py
index 3d29b646b..1835481eb 100644
--- a/mesonbuild/modules/qt.py
+++ b/mesonbuild/modules/qt.py
@@ -127,6 +127,8 @@ class QtBaseModule(ExtensionModule):
             for b in self.tools:
                 if qt_dep.bindir:
                     yield os.path.join(qt_dep.bindir, b), b
+                if qt_dep.libexecdir:
+                    yield os.path.join(qt_dep.libexecdir, b), b
                 # prefer the <tool>-qt<version> of the tool to the plain one, as we
                 # don't know what the unsuffixed one points to without calling it.
                 yield f'{b}-qt{qt_dep.qtver}', b
-- 
2.34.1

[eli-schwartz]

Fixed by #10259 and #9988