Moc: streamline how diagnostic messages are printed

If we don't have a valid Symbol to get a line number from, or if the
symbol.lineNum is -1, print a shorter message containing only the file
path. Printing: '/path/to/file:-1:1' isn't useful (and looks wrong).

Change error/defaultErrorMsg/warning/note() to delegate to one central
method, so that they all behave the same; e.g. previously warning() and
note(), guarded against printing "-1" for the line number, whereas
error() didn't.

This also makes it possible to use error() for reporting other issues
(e.g. the size of generator.strings list exceeding INT_MAX, which will
happen in a later commit).

Pick-to: 6.6
Change-Id: Iddc96e08315fae415be6a84928f845d7bceb4c5f
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 47 insertions, 14 deletions

diff --git a/src/tools/moc/parser.cpp b/src/tools/moc/parser.cpp
index 6b0308fc15..f1493518f8 100644
--- a/src/tools/moc/parser.cpp
+++ b/src/tools/moc/parser.cpp
@@ -14,43 +14,73 @@ Symbol::LexemStore Symbol::lexemStore;
 
 static const char *error_msg = nullptr;
 
+/*! \internal
+    Base implementation for printing diagnostic messages.
+
+    For example:
+        "/path/to/file:line:column: error: %s\n"
+        '%s' is replaced by \a msg. (Currently "column" is always 1).
+
+    If sym.lineNum is -1, the line and column parts aren't printed:
+        "/path/to/file: error: %s\n"
+
+    \a formatStringSuffix specifies the type of the message e.g.:
+        "error: %s\n"
+        "warning: %s\n"
+        "note: %s\n"
+        "Parse error at %s\n" (from defaultErrorMsg())
+*/
+void Parser::printMsg(QByteArrayView formatStringSuffix, QByteArrayView msg, const Symbol &sym)
+{
+    if (sym.lineNum != -1) {
 #ifdef Q_CC_MSVC
-#define ErrorFormatString "%s(%d:%d): "
+        QByteArray formatString = "%s(%d:%d): " + formatStringSuffix;
 #else
-#define ErrorFormatString "%s:%d:%d: "
+        QByteArray formatString = "%s:%d:%d: " + formatStringSuffix;
 #endif
+        fprintf(stderr, formatString.constData(),
+                currentFilenames.top().constData(), sym.lineNum, 1, msg.data());
+    } else {
+        QByteArray formatString = "%s: " + formatStringSuffix;
+        fprintf(stderr, formatString.constData(),
+                currentFilenames.top().constData(), msg.data());
+    }
+}
 
-static void defaultErrorMsg(const QByteArray &fileName, const Symbol &sym)
+void Parser::defaultErrorMsg(const Symbol &sym)
 {
-    fprintf(stderr, ErrorFormatString "error: Parse error at \"%s\"\n",
-            fileName.constData(), sym.lineNum, 1, sym.lexem().data());
+    if (sym.lineNum != -1)
+        printMsg("error: Parse error at \"%s\"\n", sym.lexem().data(), sym);
+    else
+        printMsg("error: could not parse file\n", "", sym);
 }
 
 void Parser::error(const Symbol &sym)
 {
-    defaultErrorMsg(currentFilenames.top(), sym);
+    defaultErrorMsg(sym);
     exit(EXIT_FAILURE);
 }
 
-void Parser::error(const char *msg) {
+void Parser::error(const char *msg)
+{
     if (msg || error_msg)
-        fprintf(stderr, ErrorFormatString "error: %s\n",
-                 currentFilenames.top().constData(), symbol().lineNum, 1, msg?msg:error_msg);
+        printMsg("error: %s\n",
+                 msg ? msg : error_msg,
+                 index > 0 ? symbol() : Symbol{});
     else
-        defaultErrorMsg(currentFilenames.top(), symbol());
+        defaultErrorMsg(symbol());
+
     exit(EXIT_FAILURE);
 }
 
 void Parser::warning(const char *msg) {
     if (displayWarnings && msg)
-        fprintf(stderr, ErrorFormatString "warning: %s\n",
-                currentFilenames.top().constData(), qMax(0, index > 0 ? symbol().lineNum : 0), 1, msg);
+        printMsg("warning: %s\n", msg, index > 0 ? symbol() : Symbol{});
 }
 
 void Parser::note(const char *msg) {
     if (displayNotes && msg)
-        fprintf(stderr, ErrorFormatString "note: %s\n",
-                currentFilenames.top().constData(), qMax(0, index > 0 ? symbol().lineNum : 0), 1, msg);
+        printMsg("note: %s\n", msg, index > 0 ? symbol() : Symbol{});
 }
 
 QT_END_NAMESPACE
diff --git a/src/tools/moc/parser.h b/src/tools/moc/parser.h
index dc86cdec73..715c441e89 100644
--- a/src/tools/moc/parser.h
+++ b/src/tools/moc/parser.h
@@ -5,6 +5,7 @@
 #define PARSER_H
 
 #include "symbols.h"
+#include <QtCore/qbytearrayview.h>
 
 #include <stack>
 
@@ -48,6 +49,8 @@ public:
     Q_NORETURN void error(const char *msg = nullptr);
     void warning(const char * = nullptr);
     void note(const char * = nullptr);
+    void defaultErrorMsg(const Symbol &sym);
+    void printMsg(QByteArrayView formatStringSuffix, QByteArrayView msg, const Symbol &sym);
 
 };