qbspkgconfig: fix handling empty variablesv1.23.1

Variables should be allowed to be set to empty values,
only missing variables should produce errors.

Fixes: QBS-1702
Change-Id: Ib9aac611a578a3673fb8201099a707e5842fd750
Reviewed-by: Kai Dohmen <psykai1993@googlemail.com>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

7 files changed, 51 insertions, 12 deletions

diff --git a/changelogs/changes-1.23.1.md b/changelogs/changes-1.23.1.md
index 7b936f313..65536bfeb 100644
--- a/changelogs/changes-1.23.1.md
+++ b/changelogs/changes-1.23.1.md
@@ -11,6 +11,7 @@
 
 # Other modules
 * Fixed protobuf linking on macOS 11.
+* Fixed handling empty variables in qbspkgconfig (QBS-1702)
 
 # Contributors
 * Christian Kandeler
diff --git a/src/lib/pkgconfig/pcparser.cpp b/src/lib/pkgconfig/pcparser.cpp
index cc8b0ae69..388363af6 100644
--- a/src/lib/pkgconfig/pcparser.cpp
+++ b/src/lib/pkgconfig/pcparser.cpp
@@ -475,10 +475,10 @@ std::string PcParser::trimAndSubstitute(const PcPackage &pkg, std::string_view s
 
             const auto varval = m_pkgConfig.packageGetVariable(pkg, varname);
 
-            if (varval.empty())
+            if (!varval)
                 raizeUndefinedVariableException(pkg, varname);
 
-            result += varval;
+            result += *varval;
         } else {
             result += str.front();
             str.remove_prefix(1);
diff --git a/src/lib/pkgconfig/pkgconfig.cpp b/src/lib/pkgconfig/pkgconfig.cpp
index 856c871bf..b2c3d4d71 100644
--- a/src/lib/pkgconfig/pkgconfig.cpp
+++ b/src/lib/pkgconfig/pkgconfig.cpp
@@ -217,16 +217,17 @@ const PcPackageVariant &PkgConfig::getPackage(std::string_view baseFileName) con
     return *it;
 }
 
-std::string_view PkgConfig::packageGetVariable(const PcPackage &pkg, std::string_view var) const
+std::optional<std::string_view> PkgConfig::packageGetVariable(
+    const PcPackage &pkg, std::string_view var) const
 {
-    std::string_view varval;
+    std::optional<std::string_view> result;
 
     if (var.empty())
-        return varval;
+        return result;
 
     const auto &globals = m_options.globalVariables;
     if (auto it = globals.find(var); it != globals.end())
-        varval = it->second;
+        result = it->second;
 
     // Allow overriding specific variables using an environment variable of the
     // form PKG_CONFIG_$PACKAGENAME_$VARIABLE
@@ -234,15 +235,15 @@ std::string_view PkgConfig::packageGetVariable(const PcPackage &pkg, std::string
         const std::string envVariable = varToEnvVar(pkg.baseFileName, var);
         const auto it = m_options.systemVariables.find(envVariable);
         if (it != m_options.systemVariables.end())
-            return it->second;
+            result = it->second;
     }
 
-    if (varval.empty()) {
-        const auto it = pkg.variables.find(var);
-        varval = (it != pkg.variables.end()) ? it->second : std::string_view();
+    if (!result) {
+        if (const auto it = pkg.variables.find(var); it != pkg.variables.end())
+            result = it->second;
     }
 
-    return varval;
+    return result;
 }
 
 #if HAS_STD_FILESYSTEM
diff --git a/src/lib/pkgconfig/pkgconfig.h b/src/lib/pkgconfig/pkgconfig.h
index 6da1f053f..c1cc634e3 100644
--- a/src/lib/pkgconfig/pkgconfig.h
+++ b/src/lib/pkgconfig/pkgconfig.h
@@ -72,7 +72,8 @@ public:
     const Packages &packages() const { return m_packages; }
     const PcPackageVariant &getPackage(std::string_view baseFileName) const;
 
-    std::string_view packageGetVariable(const PcPackage &pkg, std::string_view var) const;
+    std::optional<std::string_view> packageGetVariable(
+        const PcPackage &pkg, std::string_view var) const;
 
 private:
     Packages findPackages() const;
diff --git a/tests/auto/pkgconfig/testdata/empty-variable.json b/tests/auto/pkgconfig/testdata/empty-variable.json
new file mode 100644
index 000000000..b96689979
--- /dev/null
+++ b/tests/auto/pkgconfig/testdata/empty-variable.json
@@ -0,0 +1,21 @@
+{
+    "Name": "Empty Variable test",
+    "Description": "Checks that empty variables are handled correcty",
+    "Version": "1.0.0",
+    "Vars": {
+        "rootprefix": "",
+        "prefix": "/usr",
+        "exec_prefix": "//usr",
+        "libdir": "//usr/lib",
+        "includedir": "//usr/include"
+    },
+    "Libs": [
+        {"Type": "LibraryName", "Value": "simple"}
+    ],
+    "LibsPrivate": [
+        {"Type": "LibraryName", "Value": "m"}
+    ],
+    "Cflags": [
+        {"Type": "IncludePath", "Value": "//usr/include"}
+    ]
+}
diff --git a/tests/auto/pkgconfig/testdata/empty-variable.pc b/tests/auto/pkgconfig/testdata/empty-variable.pc
new file mode 100644
index 000000000..581382b7e
--- /dev/null
+++ b/tests/auto/pkgconfig/testdata/empty-variable.pc
@@ -0,0 +1,13 @@
+rootprefix=
+prefix=/usr
+exec_prefix=${rootprefix}/${prefix}
+libdir=${exec_prefix}/lib
+includedir=${rootprefix}/${prefix}/include
+
+Name: Empty Variable test
+Description: Checks that empty variables are handled correcty
+Version: 1.0.0
+Requires:
+Libs: -lsimple
+Libs.private: -lm
+Cflags: -I${includedir}
diff --git a/tests/auto/pkgconfig/tst_pkgconfig.cpp b/tests/auto/pkgconfig/tst_pkgconfig.cpp
index ec62e1a7f..220e54e7a 100644
--- a/tests/auto/pkgconfig/tst_pkgconfig.cpp
+++ b/tests/auto/pkgconfig/tst_pkgconfig.cpp
@@ -168,6 +168,8 @@ void TestPkgConfig::pkgConfig_data()
     QTest::addColumn<QString>("jsonFileName");
     QTest::addColumn<QVariantMap>("optionsMap");
 
+    QTest::newRow("empty-variable")
+            << QStringLiteral("empty-variable") << QString() << QVariantMap();
     QTest::newRow("non-l-required")
             << QStringLiteral("non-l-required") << QString() << QVariantMap();
     QTest::newRow("simple")