Avoid having division caught up in parsing of comments.

A loop to skip space and comments was meant to break on anything else
but would have not broken on a division operator (where it should) due
to it getting caught in the check for a comment-start, without falling
back suitably when it didn't complete that check.

Managed to contrive a suitably twisted change to findDeps test to
reveal the bug; broken previously, now fixed.  Not ideal, as it relied
on another bug to fail previously - backslash-newline shouldn't end a
preprocessing directive line - but it should still pass once that's
fixed, too.  Exercising a bug in qmake usually involves code that
won't compile anyway, making it tricky to write a test that reveals
the bug but that passes once it's fixed.

Change-Id: I08a1d7cc5e3d7fd1ac0a48e5c09dfdfbb7580b11
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

4 files changed, 22 insertions, 17 deletions

diff --git a/qmake/generators/makefiledeps.cpp b/qmake/generators/makefiledeps.cpp
index 8c51a20aa6..535f0561cc 100644
--- a/qmake/generators/makefiledeps.cpp
+++ b/qmake/generators/makefiledeps.cpp
@@ -509,22 +509,21 @@ bool QMakeSourceFileInfo::findDeps(SourceFile *file)
                 for(; x < buffer_len; ++x) {
                     if (buffer[x] == ' ' || buffer[x] == '\t') {
                         // keep going
-                    } else if (buffer[x] == '/') {
+                    } else if (buffer[x] == '/' && x + 1 < buffer_len &&
+                               (buffer[x + 1] == '/' || buffer[x + 1] == '*')) {
                         ++x;
-                        if(buffer_len >= x) {
-                            if (buffer[x] == '/') { // C++-style comment
-                                for (; x < buffer_len && !qmake_endOfLine(buffer[x]); ++x) {} // skip
-                                beginning = 1;
-                            } else if (buffer[x] == '*') { // C-style comment
-                                for(++x; x < buffer_len; ++x) {
-                                    if (buffer[x] == '*') {
-                                        if (x + 1 < buffer_len && buffer[x + 1] == '/') {
-                                            ++x;
-                                            break;
-                                        }
-                                    } else if (qmake_endOfLine(buffer[x])) {
-                                        ++line_count;
+                        if (buffer[x] == '/') { // C++-style comment
+                            for (; x < buffer_len && !qmake_endOfLine(buffer[x]); ++x) {} // skip
+                            beginning = 1;
+                        } else { // C-style comment
+                            while (++x < buffer_len) {
+                                if (buffer[x] == '*') {
+                                    if (x + 1 < buffer_len && buffer[x + 1] == '/') {
+                                        ++x; // skip '*'; for loop skips '/'.
+                                        break;
                                     }
+                                } else if (qmake_endOfLine(buffer[x])) {
+                                    ++line_count;
                                 }
                             }
                         }
diff --git a/tests/auto/tools/qmake/testdata/findDeps/findDeps.pro b/tests/auto/tools/qmake/testdata/findDeps/findDeps.pro
index 442c9c767f..2713296f5b 100644
--- a/tests/auto/tools/qmake/testdata/findDeps/findDeps.pro
+++ b/tests/auto/tools/qmake/testdata/findDeps/findDeps.pro
@@ -9,4 +9,4 @@ HEADERS += object1.h \
            object7.h \
            object8.h \
            object9.h
-SOURCES += main.cpp
+SOURCES += main.cpp needed.cpp
diff --git a/tests/auto/tools/qmake/testdata/findDeps/main.cpp b/tests/auto/tools/qmake/testdata/findDeps/main.cpp
index e4aa5c6251..0df3f9b7c3 100644
--- a/tests/auto/tools/qmake/testdata/findDeps/main.cpp
+++ b/tests/auto/tools/qmake/testdata/findDeps/main.cpp
@@ -31,6 +31,9 @@
 **
 ****************************************************************************/
 
+#define spurious \
+ / #include "needed.cpp"
+// if not ignored, symbol needed() won't be available ...
 
             #include <moc_object1.cpp>
 /**/        #include <moc_object2.cpp>
@@ -49,5 +52,7 @@ static void function2(); /**/
 static void function3(); //
 #include <moc_object9.cpp>
 
-int main () {}
-
+int main () {
+    extern int needed(void);
+    return needed();
+}
diff --git a/tests/auto/tools/qmake/testdata/findDeps/needed.cpp b/tests/auto/tools/qmake/testdata/findDeps/needed.cpp
new file mode 100644
index 0000000000..698d0aaa12
--- /dev/null
+++ b/tests/auto/tools/qmake/testdata/findDeps/needed.cpp
@@ -0,0 +1 @@
+extern int needed(void) { return 1; }