qmake: Add test functions for comparing version numbers

qmake really lacks version comparing functions:
users either use ugly constructions to compare versions
by components, such as
greaterThan(QT_CLANG_MAJOR_VERSION, 3)|greaterThan(QT_CLANG_MINOR_VERSION, 4):
or even incorrectly compare versions as strings:
!lessThan(apple_clang_ver, "5.1")|!lessThan(reg_clang_ver, "3.4"):

Add test functions versionAtLeast and versionAtMost which use
QVersionNumber to compare version numbers by components.

Change-Id: I65e6b3c296d0301d544b7e38bf3d44f8d555c7fc
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

1 files changed, 14 insertions, 0 deletions

diff --git a/qmake/doc/src/qmake-manual.qdoc b/qmake/doc/src/qmake-manual.qdoc
index d8ab7d096d..ceb93fde2d 100644
--- a/qmake/doc/src/qmake-manual.qdoc
+++ b/qmake/doc/src/qmake-manual.qdoc
@@ -3514,6 +3514,20 @@
 
     \snippet code/doc_src_qmake-manual.pro 169
 
+    \section2 versionAtLeast(variablename, versionNumber)
+
+    Tests that the version number from \c variablename is greater than or equal
+    to \c versionNumber. The version number is considered to be a sequence of
+    non-negative decimal numbers delimited by '.'; any non-numerical tail of
+    the string will be ignored. Comparison is performed segment-wise from left
+    to right; if one version is a prefix of the other, it is considered smaller.
+
+    \section2 versionAtMost(variablename, versionNumber)
+
+    Tests that the version number from \c variablename is less than or equal to
+    \c versionNumber. Works as
+    \l{versionAtLeast(variablename, versionNumber)}{versionAtLeast()}.
+
     \section2 warning(string)
 
     Always succeeds, and displays \c string as a warning message to the user.