C++: Better handling of arg count mismatch in macros

Do not expand function-like macros at all when there's a mismatch
in the parameter/argument count.

The report below raises the issue but its expected result is not
correct. This would be the more appropriate fix.

Task-number: QTCREATORBUG-7225
Change-Id: Ide8580faa7b724d3e8b396ec1f899cc5ca7f9e7e
Reviewed-by: hjk <qthjk@ovi.com>

src/libs/cplusplus/pp-engine.cpp

@@ -793,7 +793,25 @@ bool Preprocessor::handleIdentifier(PPToken *tk)
     if (macro->isFunctionLike()) {
         // Collect individual tokens that form the macro arguments.
         QVector<QVector<PPToken> > allArgTks;
-        if (!collectActualArguments(tk, &allArgTks)) {
+        bool hasArgs = collectActualArguments(tk, &allArgTks);
+
+        // Check for matching parameter/argument count.
+        bool hasMatchingArgs = false;
+        if (hasArgs) {
+            const int expectedArgCount = macro->formals().size();
+            const int actualArgCount = allArgTks.size();
+            if (expectedArgCount == actualArgCount
+                    || (macro->isVariadic() && actualArgCount > expectedArgCount - 1)
+                    // Handle '#define foo()' when invoked as 'foo()'
+                    || (expectedArgCount == 0
+                        && actualArgCount == 1
+                        && allArgTks.at(0).isEmpty())) {
+                 hasMatchingArgs = true;
+            }
+        }
+
+        if (!hasArgs || !hasMatchingArgs) {
+            //### TODO: error message
             pushToken(tk);
             *tk = idTk;
             return false;
@@ -872,12 +890,6 @@ bool Preprocessor::handleFunctionLikeMacro(PPToken *tk,
             int j = 0;
             for (; j < formals.size() && expanded.size() < MAX_TOKEN_EXPANSION_COUNT; ++j) {
                 if (formals[j] == id) {
-                    if (actuals.size() <= j) {
-                        // too few actual parameters
-                        //### TODO: error message
-                        goto exitNicely;
-                    }
-
                     QVector<PPToken> actualsForThisParam = actuals.at(j);
                     if (id == "__VA_ARGS__" || (macro->isVariadic() && j + 1 == formals.size())) {
                         unsigned lineno = 0;
@@ -929,7 +941,6 @@ bool Preprocessor::handleFunctionLikeMacro(PPToken *tk,
         }
     }
 
-exitNicely:
     pushToken(tk);
     if (addWhitespaceMarker) {
         PPToken forceWhitespacingToken;

tests/auto/cplusplus/preprocessor/tst_preprocessor.cpp

@@ -300,10 +300,6 @@ protected:
     }
     static QString simplified(QByteArray buf);
 
-private /* not corrected yet */:
-    void param_expanding_as_multiple_params();
-    void macro_argument_expansion();
-
 private slots:
     void defined();
     void defined_data();
@@ -447,49 +443,21 @@ void tst_Preprocessor::macro_args_count()
 
 void tst_Preprocessor::invalid_param_count()
 {
-    Client *client = 0; // no client.
-    Environment env;
-
-    Preprocessor preprocess(client, &env);
-    // The following is illegal, but shouldn't crash the preprocessor.
-    // GCC says: 3:14: error: macro "foo" requires 2 arguments, but only 1 given
-    QByteArray preprocessed = preprocess.run(QLatin1String("<stdin>"),
-                                                "\n#define foo(a,b) int f(a,b);"
-                                                "\n#define ARGS(t)  t a,t b"
-                                                "\nfoo(ARGS(int))",
-                                             true, false);
-    // do not verify the output: it's illegal, so anything might be outputted.
-}
-
-void tst_Preprocessor::param_expanding_as_multiple_params()
-{
-    Client *client = 0; // no client.
     Environment env;
+    QByteArray output;
+    MockClient client(&env, &output);
+    Preprocessor preprocess(&client, &env);
+    // The following are illegal, but shouldn't crash the preprocessor.
+    preprocess.run(QLatin1String("<stdin>"),
+                   "\n#define foo(a,b) int f(a,b);"
+                   "\n#define ARGS(t)  t a,t b"
+                   "\nfoo(ARGS(int))"
+                   "\nfoo()"
+                   "\nfoo(int a, int b, int c)",
+                   true, false);
 
-    Preprocessor preprocess(client, &env);
-    QByteArray preprocessed = preprocess.run(QLatin1String("<stdin>"),
-                                                "\n#define foo(a,b) int f(a,b);"
-                                                "\n#define ARGS(t)  t a,t b"
-                                                "\nfoo(ARGS(int))",
-                                            false, true);
-    QCOMPARE(simplified(preprocessed), QString("int f(int a,int b);"));
-}
-
-void tst_Preprocessor::macro_argument_expansion() //QTCREATORBUG-7225
-{
-    Client *client = 0; // no client.
-    Environment env;
-
-    Preprocessor preprocess(client, &env);
-    QByteArray preprocessed = preprocess.run(QLatin1String("<stdin>"),
-                                                "\n#define BAR1        2,3,4"
-                                                "\n#define FOO1(a,b,c) a+b+c"
-                                                "\nvoid test2(){"
-                                                "\nint x=FOO1(BAR1);"
-                                                "\n}",
-                                            false, true);
-    QCOMPARE(simplified(preprocessed), QString("void test2(){int x=2+3+4;}"));
-
+    // Output is not that relevant but check that nothing triggered expansion.
+    QCOMPARE(client.macroArgsCount(), QList<int>());
 }
 
 void tst_Preprocessor::macro_uses()