qmake: skip empty parts when splitting strings in some more places

... and make it explicit where we can't do that for semantical or
backwards compat reasons.

most urgently, this fixes an assertion failure when $QMAKEFEATURES
contains empty paths (e.g., due to a trailing semicolon).

notable observation: QByteArray::split() has no argument for the split
behavior (it always keeps empty parts).

Task-number: QTBUG-47325
Change-Id: I72d4b2e154a2ed1802cfa98fb4a5211a68e43231
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

3 files changed, 10 insertions, 6 deletions

diff --git a/qmake/library/qmakebuiltins.cpp b/qmake/library/qmakebuiltins.cpp
index c1d446263e..02ad3220d3 100644
--- a/qmake/library/qmakebuiltins.cpp
+++ b/qmake/library/qmakebuiltins.cpp
@@ -738,7 +738,8 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinExpand(
             const QString &sep = (args.count() == 2) ? args.at(1).toQString(m_tmp1) : statics.field_sep;
             const auto vars = values(map(args.at(0)));
             for (const ProString &var : vars) {
-                const auto splits = var.toQStringRef().split(sep);
+                // FIXME: this is inconsistent with the "there are no empty strings" dogma.
+                const auto splits = var.toQStringRef().split(sep, QString::KeepEmptyParts);
                 for (const auto &splt : splits)
                     ret << ProString(splt).setSource(var);
             }
@@ -1445,7 +1446,8 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
         }
         if (args.count() == 1)
             return returnBool(isActiveConfig(args.at(0).toQStringRef()));
-        const auto mutuals = args.at(1).toQStringRef().split(QLatin1Char('|'));
+        const auto mutuals = args.at(1).toQStringRef().split(QLatin1Char('|'),
+                                                             QString::SkipEmptyParts);
         const ProStringList &configs = values(statics.strCONFIG);
 
         for (int i = configs.size() - 1; i >= 0; i--) {
@@ -1477,7 +1479,8 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
                     return ReturnTrue;
             }
         } else {
-            const auto mutuals = args.at(2).toQStringRef().split(QLatin1Char('|'));
+            const auto mutuals = args.at(2).toQStringRef().split(QLatin1Char('|'),
+                                                                 QString::SkipEmptyParts);
             for (int i = l.size() - 1; i >= 0; i--) {
                 const ProString val = l[i];
                 for (int mut = 0; mut < mutuals.count(); mut++) {
diff --git a/qmake/library/qmakeevaluator.cpp b/qmake/library/qmakeevaluator.cpp
index 7112b57c11..6b23412327 100644
--- a/qmake/library/qmakeevaluator.cpp
+++ b/qmake/library/qmakeevaluator.cpp
@@ -297,6 +297,7 @@ ProStringList QMakeEvaluator::split_value_list(const QStringRef &vals, int sourc
         case '\'':
             if (!quote)
                 quote = unicode;
+            // FIXME: this is inconsistent with the "there are no empty strings" dogma.
             hadWord = true;
             break;
         case ' ':
@@ -879,7 +880,7 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::visitProVariable(
             return ReturnTrue;
         }
         QChar sep = val.at(1);
-        auto func = val.split(sep);
+        auto func = val.split(sep, QString::KeepEmptyParts);
         if (func.count() < 3 || func.count() > 4) {
             evalError(fL1S("The s/// function expects 3 or 4 arguments."));
             return ReturnTrue;
@@ -1018,7 +1019,7 @@ static ProString msvcArchitecture(const QString &vcInstallDir, const QString &pa
     QString vcBinDir = vcInstallDir;
     if (vcBinDir.endsWith(QLatin1Char('\\')))
         vcBinDir.chop(1);
-    const auto dirs = pathVar.split(QLatin1Char(';'));
+    const auto dirs = pathVar.split(QLatin1Char(';'), QString::SkipEmptyParts);
     for (const QString &dir : dirs) {
         if (!dir.startsWith(vcBinDir, Qt::CaseInsensitive))
             continue;
diff --git a/qmake/library/qmakeglobals.cpp b/qmake/library/qmakeglobals.cpp
index 452b44c045..daf4707779 100644
--- a/qmake/library/qmakeglobals.cpp
+++ b/qmake/library/qmakeglobals.cpp
@@ -261,7 +261,7 @@ QStringList QMakeGlobals::splitPathList(const QString &val) const
     QStringList ret;
     if (!val.isEmpty()) {
         QString cwd(QDir::currentPath());
-        const QStringList vals = val.split(dirlist_sep);
+        const QStringList vals = val.split(dirlist_sep, QString::SkipEmptyParts);
         ret.reserve(vals.length());
         for (const QString &it : vals)
             ret << IoUtils::resolvePath(cwd, it);