move generation of qconfig.cpp (and qt.conf) to qmake-based configure

this moves us another step towards the "outer" configure doing just
minimal bootstrapping of qmake.

a challenge here was that so far, qmake itself needed qconfig.cpp. this
was replaced by usage of a qt.conf file instead of compiled-in values.
however, to make the executable still self-contained, that qt.conf is
embedded into it (by simple appending of a fixed signature and the text
file).

the qmake with the embedded qt.conf is not used for the qt build itself,
which instead relies on the qt.conf in bin/ as before. however, due to
the missing built-in values, this file now needs to contain more
information than before. but except for a minimal version that is needed
to start up qmake/configure at all, that file is now also generated with
qmake. as some of the newly set up properties are subsequently used by
configure itself, qmake gains a (deliberately undocumented) function to
reload the qt.conf after it's fully populated.

unlike the old implementations, this one doesn't emit redundant qt.conf
entries which match the hard-coded fallbacks. omitting them leads to
leaner files which are more comprehensible.

Started-by: Paolo Angelelli <paolo.angelelli@qt.io>
Change-Id: I4526ef64b3c89d9851e10f83965fe479ed7f39f6
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

2 files changed, 8 insertions, 1 deletions

diff --git a/qmake/library/qmakebuiltins.cpp b/qmake/library/qmakebuiltins.cpp
index 7648b9373d..b30373b596 100644
--- a/qmake/library/qmakebuiltins.cpp
+++ b/qmake/library/qmakebuiltins.cpp
@@ -101,7 +101,7 @@ enum TestFunc {
     T_EXISTS, T_EXPORT, T_CLEAR, T_UNSET, T_EVAL, T_CONFIG, T_SYSTEM,
     T_DEFINED, T_DISCARD_FROM, T_CONTAINS, T_INFILE,
     T_COUNT, T_ISEMPTY, T_PARSE_JSON, T_INCLUDE, T_LOAD, T_DEBUG, T_LOG, T_MESSAGE, T_WARNING, T_ERROR, T_IF,
-    T_MKPATH, T_WRITE_FILE, T_TOUCH, T_CACHE
+    T_MKPATH, T_WRITE_FILE, T_TOUCH, T_CACHE, T_RELOAD_PROPERTIES
 };
 
 void QMakeEvaluator::initFunctionStatics()
@@ -200,6 +200,7 @@ void QMakeEvaluator::initFunctionStatics()
         { "write_file", T_WRITE_FILE },
         { "touch", T_TOUCH },
         { "cache", T_CACHE },
+        { "reload_properties", T_RELOAD_PROPERTIES },
     };
     statics.functions.reserve((int)(sizeof(testInits)/sizeof(testInits[0])));
     for (unsigned i = 0; i < sizeof(testInits)/sizeof(testInits[0]); ++i)
@@ -2015,6 +2016,11 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinConditional(
         }
         return writeFile(fL1S("cache "), fn, QIODevice::Append, false, varstr);
     }
+    case T_RELOAD_PROPERTIES:
+#ifdef QT_BUILD_QMAKE
+        m_option->reloadProperties();
+#endif
+        return ReturnTrue;
     default:
         evalError(fL1S("Function '%1' is not implemented.").arg(function.toQString(m_tmp1)));
         return ReturnFalse;
diff --git a/qmake/library/qmakeglobals.h b/qmake/library/qmakeglobals.h
index 96c39fa168..1bb8632883 100644
--- a/qmake/library/qmakeglobals.h
+++ b/qmake/library/qmakeglobals.h
@@ -125,6 +125,7 @@ public:
     void setDirectories(const QString &input_dir, const QString &output_dir);
 #ifdef QT_BUILD_QMAKE
     void setQMakeProperty(QMakeProperty *prop) { property = prop; }
+    void reloadProperties() { property->reload(); }
     ProString propertyValue(const ProKey &name) const { return property->value(name); }
 #else
 #  ifdef PROEVALUATOR_INIT_PROPS