shiboken: Improve handling of pointer types for CONVERTTOCPP in injected code

Code snippets like:
QByteArray *cppSelf = %CONVERTTOCPP[QByteArray *](obj);

cause an assert in shiboken since the '*' is captured into
the target of the assignment and is not considered part of the type.

Make the error message a bit clearer and add documentation.

Fixes: PYSIDE-1037
Change-Id: Ie8da2f57ba91325ea677e1a00852e91726c0e09b
Reviewed-by: Christian Tismer <tismer@stackless.com>

4 files changed, 47 insertions, 4 deletions

diff --git a/sources/shiboken2/ApiExtractor/messages.cpp b/sources/shiboken2/ApiExtractor/messages.cpp
index a6e75aac3..5b3a57fcc 100644
--- a/sources/shiboken2/ApiExtractor/messages.cpp
+++ b/sources/shiboken2/ApiExtractor/messages.cpp
@@ -311,6 +311,23 @@ QString msgCannotUseEnumAsInt(const QString &name)
                         "Compilation errors may occur when used as a function argument.");
 }
 
+QString msgConversionTypesDiffer(const QString &varType, const QString &conversionType)
+{
+    QString result;
+    QTextStream str(&result);
+    str << "Types of receiver variable ('" << varType
+         << "') and %%CONVERTTOCPP type system variable ('" << conversionType
+         << "') differ";
+    QString strippedVarType = varType;
+    QString strippedConversionType = conversionType;
+    TypeInfo::stripQualifiers(&strippedVarType);
+    TypeInfo::stripQualifiers(&strippedConversionType);
+    if (strippedVarType == strippedConversionType)
+        str << " in qualifiers. Please make sure the type is a distinct token";
+    str << '.';
+    return result;
+}
+
 // main.cpp
 
 QString msgLeftOverArguments(const QMap<QString, QString> &remainingArgs)
diff --git a/sources/shiboken2/ApiExtractor/messages.h b/sources/shiboken2/ApiExtractor/messages.h
index ab2bf64b6..2fee0de8f 100644
--- a/sources/shiboken2/ApiExtractor/messages.h
+++ b/sources/shiboken2/ApiExtractor/messages.h
@@ -115,6 +115,8 @@ QString msgCannotOpenForWriting(const QFile &f);
 
 QString msgCannotUseEnumAsInt(const QString &name);
 
+QString msgConversionTypesDiffer(const QString &varType, const QString &conversionType);
+
 QString msgLeftOverArguments(const QMap<QString, QString> &remainingArgs);
 
 QString msgInvalidVersion(const QString &package, const QString &version);
diff --git a/sources/shiboken2/doc/typesystemvariables.rst b/sources/shiboken2/doc/typesystemvariables.rst
index a07ba0d8c..b1b9bbfe6 100644
--- a/sources/shiboken2/doc/typesystemvariables.rst
+++ b/sources/shiboken2/doc/typesystemvariables.rst
@@ -126,6 +126,29 @@ Variables
   Replaced by a |project| conversion call that converts a Python variable
   to a C++ variable of the type indicated by ``CPPTYPE``.
 
+   Typically, this is a variable assignment:
+
+      .. code-block:: c++
+
+         double value = %CONVERTTOCPP[double](pyValue);
+
+   Pointer assignments are also possible:
+
+      .. code-block:: c++
+
+         void f(double *valuePtr)
+         {
+             *valuePtr = %CONVERTTOCPP[double](pyValue);
+
+   Note however, that for variable definitions, the type must
+   be a space-delimited token:
+
+      .. code-block:: c++
+
+         double * valuePtr = %CONVERTTOCPP[double](pyValue);
+
+   since it otherwise would be indistinguishable from the pointer assignment
+   above.
 
 .. _converttopython:
 
diff --git a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
index 8e27777d6..e41c91716 100644
--- a/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
+++ b/sources/shiboken2/generator/shiboken2/shibokengenerator.cpp
@@ -149,6 +149,8 @@ ShibokenGenerator::ShibokenGenerator()
     const char CHECKTYPE_REGEX[] = R"(%CHECKTYPE\[([^\[]*)\]\()";
     const char ISCONVERTIBLE_REGEX[] = R"(%ISCONVERTIBLE\[([^\[]*)\]\()";
     const char CONVERTTOPYTHON_REGEX[] = R"(%CONVERTTOPYTHON\[([^\[]*)\]\()";
+    // Capture a '*' leading the variable name into the target
+    // so that "*valuePtr = %CONVERTTOCPP..." works as expected.
     const char CONVERTTOCPP_REGEX[] =
         R"((\*?%?[a-zA-Z_][\w\.]*(?:\[[^\[^<^>]+\])*)(?:\s+)=(?:\s+)%CONVERTTOCPP\[([^\[]*)\]\()";
     m_typeSystemConvRegEx[TypeSystemCheckFunction]         = QRegularExpression(QLatin1String(CHECKTYPE_REGEX));
@@ -2044,10 +2046,9 @@ void ShibokenGenerator::replaceConverterTypeSystemVariable(TypeSystemConverterVa
                 varType = miniNormalizer(varType);
                 QString varName = list.at(1).trimmed();
                 if (!varType.isEmpty()) {
-                    if (varType != conversionType->cppSignature()) {
-                        qFatal("Types of receiver variable ('%s') and %%CONVERTTOCPP type system variable ('%s') differ.",
-                               qPrintable(varType), qPrintable(conversionType->cppSignature()));
-                    }
+                    const QString conversionSignature = conversionType->cppSignature();
+                    if (varType != conversionSignature)
+                        qFatal("%s", qPrintable(msgConversionTypesDiffer(varType, conversionSignature)));
                     c << getFullTypeName(conversionType) << ' ' << varName;
                     writeMinimalConstructorExpression(c, conversionType);
                     c << ';' << endl;