From a13e97b42c89159667f2d89c7eda2dbfdf1465e8 Mon Sep 17 00:00:00 2001
From: Robin Burchell <robin.burchell@collabora.co.uk>
Date: Mon, 17 Jan 2011 13:31:44 +0100
Subject: Add packagesExist() function to qmake.

This can be used to detect whether or not a given (set of) packages exist,
which can be useful for compiling in or our extra functionality at build time.

Merge-request: 1022
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
---
 doc/src/development/qmake-manual.qdoc           | 13 +++++++++++++
 doc/src/snippets/code/doc_src_qmake-manual.qdoc | 12 ++++++++++++
 mkspecs/features/link_pkgconfig.prf             |  3 ++-
 mkspecs/features/qt_functions.prf               | 14 ++++++++++++++
 4 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/doc/src/development/qmake-manual.qdoc b/doc/src/development/qmake-manual.qdoc
index d7a48a3..b6270d5 100644
--- a/doc/src/development/qmake-manual.qdoc
+++ b/doc/src/development/qmake-manual.qdoc
@@ -3397,6 +3397,19 @@
 
     \tableofcontents{2}
 
+    \section1 packagesExist(packages)
+
+    Uses the PKGCONFIG mechanism to determine whether or not the given packages
+    exist at the time of project parsing.
+
+    This can be useful to optionally enable or disable features. For example:
+
+    \snippet doc/src/snippets/code/doc_src_qmake-manual.qdoc 157
+
+    And then, in the code:
+
+    \snippet doc/src/snippets/code/doc_src_qmake-manual.qdoc 158
+
     \section1 basename(variablename)
 
     Returns the basename of the file specified. For example:
diff --git a/doc/src/snippets/code/doc_src_qmake-manual.qdoc b/doc/src/snippets/code/doc_src_qmake-manual.qdoc
index ab67a3d..ec35a52 100644
--- a/doc/src/snippets/code/doc_src_qmake-manual.qdoc
+++ b/doc/src/snippets/code/doc_src_qmake-manual.qdoc
@@ -1029,3 +1029,15 @@ DEPLOYMENT += dep_note
 //! [156]
 DEPLOYMENT.display_name = My Qt App
 //! [156]
+
+//! [157]
+packagesExist(sqlite3 QtNetwork QtDeclarative) {
+    DEFINES += USE_FANCY_UI
+}
+//! [157]
+
+//! [158]
+#ifdef USE_FANCY_UI
+    // Use the fancy UI, as we have extra packages available
+#endif
+//! [158]
diff --git a/mkspecs/features/link_pkgconfig.prf b/mkspecs/features/link_pkgconfig.prf
index d70e5de..b1b00e43 100644
--- a/mkspecs/features/link_pkgconfig.prf
+++ b/mkspecs/features/link_pkgconfig.prf
@@ -1,5 +1,6 @@
 # handle pkg-config files
-isEmpty(PKG_CONFIG):PKG_CONFIG = pkg-config
+isEmpty(PKG_CONFIG):PKG_CONFIG = pkg-config # keep consistent with qt_functions.prf too!
+
 for(PKGCONFIG_LIB, $$list($$unique(PKGCONFIG))) {
     QMAKE_CXXFLAGS += $$system($$PKG_CONFIG --cflags $$PKGCONFIG_LIB)
     QMAKE_CFLAGS += $$system($$PKG_CONFIG --cflags $$PKGCONFIG_LIB)
diff --git a/mkspecs/features/qt_functions.prf b/mkspecs/features/qt_functions.prf
index 964e13b..f1c3e13 100644
--- a/mkspecs/features/qt_functions.prf
+++ b/mkspecs/features/qt_functions.prf
@@ -103,3 +103,17 @@ defineTest(qtPrepareTool) {
     }
     export($$1)
 }
+
+defineTest(packagesExist) {
+    # this can't be done in global scope here because qt_functions is loaded
+    # before the .pro is parsed, so if the .pro set PKG_CONFIG, we wouldn't know it
+    # yet. oops.
+    isEmpty(PKG_CONFIG):PKG_CONFIG = pkg-config # keep consistent with link_pkgconfig.prf! too
+
+    for(package, ARGS) {
+        !system($$PKG_CONFIG --exists $$package):return(false)
+    }
+
+    return(true)
+}
+
-- 
cgit v0.12