moc: get the system #defines from the compiler itself

In order for moc to properly parse #ifdefs and family, we've had
QMAKE_COMPILER_DEFINES as a list of pre-defined macros from the
compiler. That list is woefully incomplete.

Instead, let's simply ask the compiler for the list. With GCC and
family, we use the -dM flag while preprocessing. With ICC on Windows,
the flag gains an extra "Q" but is otherwise the same. For MSVC, it
requires using some undocumented switches and parsing environment
variables (I've tested MSVC 2012, 2013 and 2015).

The new moc option is called --include to be similar to GCC's -include
option. It does more than just parse a list of pre-defined macros and
can be used to insert any sort of code that moc needs to parse prior to
the main file.

Change-Id: I7de033f80b0e4431b7f1ffff13fca02dbb60a0a6
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

3 files changed, 50 insertions, 26 deletions

diff --git a/src/tools/moc/main.cpp b/src/tools/moc/main.cpp
index 0c327a641f..c111fa4e6b 100644
--- a/src/tools/moc/main.cpp
+++ b/src/tools/moc/main.cpp
@@ -263,6 +263,11 @@ int runMoc(int argc, char **argv)
     prependIncludeOption.setValueName(QStringLiteral("file"));
     parser.addOption(prependIncludeOption);
 
+    QCommandLineOption includeOption(QStringLiteral("include"));
+    includeOption.setDescription(QStringLiteral("Parse <file> as an #include before the main source(s)."));
+    includeOption.setValueName(QStringLiteral("file"));
+    parser.addOption(includeOption);
+
     QCommandLineOption noNotesWarningsCompatOption(QStringLiteral("n"));
     noNotesWarningsCompatOption.setDescription(QStringLiteral("Do not display notes (-nn) or warnings (-nw). Compatibility option."));
     noNotesWarningsCompatOption.setValueName(QStringLiteral("which"));
@@ -420,7 +425,17 @@ int runMoc(int argc, char **argv)
     moc.includes = pp.includes;
 
     // 1. preprocess
-    moc.symbols = pp.preprocessed(moc.filename, &in);
+    const auto includeFiles = parser.values(includeOption);
+    for (const QString &includeName : includeFiles) {
+        QByteArray rawName = pp.resolveInclude(QFile::encodeName(includeName), moc.filename);
+        QFile f(QFile::decodeName(rawName));
+        if (f.open(QIODevice::ReadOnly)) {
+            moc.symbols += Symbol(0, MOC_INCLUDE_BEGIN, rawName);
+            moc.symbols += pp.preprocessed(rawName, &f);
+            moc.symbols += Symbol(0, MOC_INCLUDE_END, rawName);
+        }
+    }
+    moc.symbols += pp.preprocessed(moc.filename, &in);
 
     // We obviously do not support MS extensions
     pp.macros.remove("_MSC_EXTENSIONS");
diff --git a/src/tools/moc/preprocessor.cpp b/src/tools/moc/preprocessor.cpp
index 14d1cd46dc..b9359ff3f4 100644
--- a/src/tools/moc/preprocessor.cpp
+++ b/src/tools/moc/preprocessor.cpp
@@ -1004,6 +1004,36 @@ static void mergeStringLiterals(Symbols *_symbols)
     }
 }
 
+QByteArray Preprocessor::resolveInclude(const QByteArray &include, const QByteArray &relativeTo)
+{
+    // #### stringery
+    QFileInfo fi;
+    if (!relativeTo.isEmpty())
+        fi.setFile(QFileInfo(QString::fromLocal8Bit(relativeTo.constData())).dir(), QString::fromLocal8Bit(include.constData()));
+    for (int j = 0; j < Preprocessor::includes.size() && !fi.exists(); ++j) {
+        const IncludePath &p = Preprocessor::includes.at(j);
+        if (p.isFrameworkPath) {
+            const int slashPos = include.indexOf('/');
+            if (slashPos == -1)
+                continue;
+            fi.setFile(QString::fromLocal8Bit(p.path + '/' + include.left(slashPos) + ".framework/Headers/"),
+                       QString::fromLocal8Bit(include.mid(slashPos + 1).constData()));
+        } else {
+            fi.setFile(QString::fromLocal8Bit(p.path.constData()), QString::fromLocal8Bit(include.constData()));
+        }
+        // try again, maybe there's a file later in the include paths with the same name
+        // (186067)
+        if (fi.isDir()) {
+            fi = QFileInfo();
+            continue;
+        }
+    }
+
+    if (!fi.exists() || fi.isDir())
+        return QByteArray();
+    return fi.canonicalFilePath().toLocal8Bit();
+}
+
 void Preprocessor::preprocess(const QByteArray &filename, Symbols &preprocessed)
 {
     currentFilenames.push(filename);
@@ -1024,32 +1054,9 @@ void Preprocessor::preprocess(const QByteArray &filename, Symbols &preprocessed)
                 continue;
             until(PP_NEWLINE);
 
-            // #### stringery
-            QFileInfo fi;
-            if (local)
-                fi.setFile(QFileInfo(QString::fromLocal8Bit(filename.constData())).dir(), QString::fromLocal8Bit(include.constData()));
-            for (int j = 0; j < Preprocessor::includes.size() && !fi.exists(); ++j) {
-                const IncludePath &p = Preprocessor::includes.at(j);
-                if (p.isFrameworkPath) {
-                    const int slashPos = include.indexOf('/');
-                    if (slashPos == -1)
-                        continue;
-                    fi.setFile(QString::fromLocal8Bit(p.path + '/' + include.left(slashPos) + ".framework/Headers/"),
-                               QString::fromLocal8Bit(include.mid(slashPos + 1).constData()));
-                } else {
-                    fi.setFile(QString::fromLocal8Bit(p.path.constData()), QString::fromLocal8Bit(include.constData()));
-                }
-                // try again, maybe there's a file later in the include paths with the same name
-                // (186067)
-                if (fi.isDir()) {
-                    fi = QFileInfo();
-                    continue;
-                }
-            }
-
-            if (!fi.exists() || fi.isDir())
+            include = resolveInclude(include, local ? filename : QByteArray());
+            if (include.isNull())
                 continue;
-            include = fi.canonicalFilePath().toLocal8Bit();
 
             if (Preprocessor::preprocessedIncludes.contains(include))
                 continue;
@@ -1204,6 +1211,7 @@ Symbols Preprocessor::preprocessed(const QByteArray &filename, QFile *file)
     input = cleaned(input);
 
     // phase 2: tokenize for the preprocessor
+    index = 0;
     symbols = tokenize(input);
 
 #if 0
diff --git a/src/tools/moc/preprocessor.h b/src/tools/moc/preprocessor.h
index 9a49751eb0..a7eb1a19e1 100644
--- a/src/tools/moc/preprocessor.h
+++ b/src/tools/moc/preprocessor.h
@@ -62,6 +62,7 @@ public:
     QList<QByteArray> frameworks;
     QSet<QByteArray> preprocessedIncludes;
     Macros macros;
+    QByteArray resolveInclude(const QByteArray &filename, const QByteArray &relativeTo);
     Symbols preprocessed(const QByteArray &filename, QFile *device);
 
     void parseDefineArguments(Macro *m);