qt-build-utils: ensure that Command has clean environment

Otherwise when executing Qt binaries if LD_LIBRARY_PATH is set
collisions can occur with differing Qt binary and libraries.

Author: ahayzen-kdab

crates/qt-build-utils/src/installation/qmake.rs

@@ -118,6 +118,9 @@ impl TryFrom<PathBuf> for QtInstallationQMake {
         // Attempt to read the QT_VERSION from qmake
         let qmake_version = match Command::new(&qmake_path)
             .args(["-query", "QT_VERSION"])
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .output()
         {
             Err(e) if e.kind() == ErrorKind::NotFound => Err(QtBuildError::QtMissing),
@@ -211,6 +214,9 @@ impl QtInstallationQMake {
         String::from_utf8_lossy(
             &Command::new(&self.qmake_path)
                 .args(["-query", var_name])
+                // Binaries should work without environment and this prevents
+                // LD_LIBRARY_PATH from causing different Qt version clashes
+                .env_clear()
                 .output()
                 .unwrap()
                 .stdout,
@@ -267,7 +273,12 @@ impl QtInstallationQMake {
         // Find the first valid executable path
         .find_map(|qmake_query_var| {
             let executable_path = PathBuf::from(self.qmake_query(qmake_query_var)).join(tool_name);
-            let test_output = Command::new(&executable_path).args(["-help"]).output();
+            let test_output = Command::new(&executable_path)
+                .args(["-help"])
+                // Binaries should work without environment and this prevents
+                // LD_LIBRARY_PATH from causing different Qt version clashes
+                .env_clear()
+                .output();
             match test_output {
                 Err(_err) => {
                     failed_paths.push(executable_path);

crates/qt-build-utils/src/tool/moc.rs

@@ -123,6 +123,9 @@ impl QtToolMoc {
             .arg(output_path.to_str().unwrap())
             .arg("--output-json");
         let cmd = cmd
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .output()
             .unwrap_or_else(|_| panic!("moc failed for {}", input_path.display()));
 

crates/qt-build-utils/src/tool/qmlcachegen.rs

@@ -83,6 +83,9 @@ impl QtToolQmlCacheGen {
 
         let cmd = Command::new(&self.executable)
             .args(common_args.iter().chain(&specific_args))
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .output()
             .unwrap_or_else(|_| {
                 panic!(
@@ -140,6 +143,9 @@ impl QtToolQmlCacheGen {
                     .chain(&specific_args)
                     .chain(qml_resource_paths),
             )
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .output()
             .unwrap_or_else(|_| panic!("qmlcachegen failed for QML module {uri}"));
         if !cmd.status.success() {

crates/qt-build-utils/src/tool/qmltyperegistrar.rs

@@ -72,6 +72,9 @@ impl QtToolQmlTypeRegistrar {
         args.extend(metatypes_json);
         let cmd = Command::new(&self.executable)
             .args(args)
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .output()
             .unwrap_or_else(|_| panic!("qmltyperegistrar failed for {uri}"));
         if !cmd.status.success() {

crates/qt-build-utils/src/tool/qtpaths.rs

@@ -74,6 +74,9 @@ impl QtToolQtPaths {
         // Run the qtpaths command and trim the output
         let output = Command::new(&self.executable)
             .args(args)
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             // NOTE: Qt 5 will fail as there is no -query parameter
             .output()
             .ok()?

crates/qt-build-utils/src/tool/rcc.rs

@@ -72,6 +72,9 @@ impl QtToolRcc {
         args.extend(self.custom_args.iter().cloned());
 
         let cmd = Command::new(&self.executable)
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .args(args)
             .output()
             .unwrap_or_else(|_| panic!("rcc failed for {}", input_path.display()));
@@ -104,6 +107,9 @@ impl QtToolRcc {
         let input_path = input_file.as_ref();
         let cmd_list = Command::new(&self.executable)
             .args(["--list", input_path.to_str().unwrap()])
+            // Binaries should work without environment and this prevents
+            // LD_LIBRARY_PATH from causing different Qt version clashes
+            .env_clear()
             .output()
             .unwrap_or_else(|_| panic!("rcc --list failed for {}", input_path.display()));