Long live qbs-pkgconfig!

This patchset introduce a static library for parsing .pc files. Code is
based on the original pkg-config source code https://
gitlab.freedesktop.org/pkg-config/pkg-config and is written in pure C++
(except for the places where we need access to filesystem as
std::filesystem is not available for all platforms - in that case, Qt
classes are used)

Parsing .pc files manually allows to have more control over dependencies
between modules, e.g. to generate a standalone module per one .pc file
and merge properties using Qbs itself, not via pkg-config.

Library is almost feature-complete and all tests copied from pkg-config
pass. Some functionality is omitted (e.g. prefix variables (what is
this?) or validating dependencies since Qbs does this as well)

Bechmark shows that parsing ~100 files takes about 10-15ms. Running
pkg-config on the same set of files takes ~4 seconds:

RESULT : TestPkgConfig::benchSystem():
     14 msecs per iteration (total: 57, iterations: 4)

Fixes: QBS-1615
Change-Id: I5bfdfa588aa04d9d69fd738dd2beea14174c0242
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

1 files changed, 61 insertions, 0 deletions

diff --git a/src/lib/pkgconfig/pkgconfig.qbs b/src/lib/pkgconfig/pkgconfig.qbs
new file mode 100644
index 000000000..25bcb3fdf
--- /dev/null
+++ b/src/lib/pkgconfig/pkgconfig.qbs
@@ -0,0 +1,61 @@
+import qbs.FileInfo
+import qbs.Utilities
+
+QbsStaticLibrary {
+    Depends { name: "cpp" }
+    Depends { name: "qbsbuildconfig" }
+
+    property stringList pcPaths: {
+        var result = [];
+        result.push(FileInfo.joinPaths(qbs.installPrefix, qbsbuildconfig.libDirName, "pkgconfig"));
+        result.push(FileInfo.joinPaths(qbs.installPrefix, "share", "pkgconfig"));
+        if (qbs.hostOS.contains("unix")) {
+            result.push("/usr/lib/pkgconfig/")
+            result.push("/usr/share/pkgconfig/")
+        }
+        return result
+    }
+    readonly property stringList pcPathsString: pcPaths.join(qbs.pathListSeparator)
+
+    property bool withQtSupport: true
+
+    readonly property stringList publicDefines: {
+        var result = [];
+        if (withQtSupport)
+            result.push("QBS_PC_WITH_QT_SUPPORT=1")
+        else
+            result.push("QBS_PC_WITH_QT_SUPPORT=0")
+        return result;
+    }
+
+    name: "qbspkgconfig"
+
+    files: [
+        "pcpackage.cpp",
+        "pcpackage.h",
+        "pcparser.cpp",
+        "pcparser.h",
+        "pkgconfig.cpp",
+        "pkgconfig.h",
+    ]
+
+    cpp.defines: {
+        var result = [
+            "PKG_CONFIG_PC_PATH=\"" + pcPathsString + "\"",
+            "PKG_CONFIG_SYSTEM_LIBRARY_PATH=\"/usr/" + qbsbuildconfig.libDirName + "\"",
+        ]
+        if ((qbs.targetOS.contains("darwin")
+                && Utilities.versionCompare(cpp.minimumMacosVersion, "10.15") < 0)
+                || qbs.toolchain.contains("mingw"))
+            result.push("HAS_STD_FILESYSTEM=0")
+        else
+            result.push("HAS_STD_FILESYSTEM=1")
+        result = result.concat(publicDefines);
+        return result
+    }
+
+    Export {
+        Depends { name: "cpp" }
+        cpp.defines: exportingProduct.publicDefines
+    }
+}