[PATCH] D23316: [analyzer] Fixed the false-positives caused by macro generated code.

[Artem Dergachev via cfe-commits]

NoQ added a comment.

No comments of my own, the patch looks good :)


================
Comment at: lib/Analysis/CloneDetection.cpp:436
@@ +435,3 @@
+    if (IsInMacro) {
+      Signature.Complexity = 0;
+    }
----------------
omtcyfz wrote:
> omtcyfz wrote:
> > omtcyfz wrote:
> > > NoQ wrote:
> > > > omtcyfz wrote:
> > > > > Do I understand correctly that a code generated by a macro doesn't affect "complexity" at all then?
> > > > > 
> > > > > ```
> > > > > TEST_F(QueryParserTest, Complete) {
> > > > >   std::vector<llvm::LineEditor::Completion> Comps =
> > > > >       QueryParser::complete("", 0, QS);
> > > > >   ASSERT_EQ(6u, Comps.size());
> > > > >   EXPECT_EQ("help ", Comps[0].TypedText);
> > > > >   EXPECT_EQ("help", Comps[0].DisplayText);
> > > > >   EXPECT_EQ("let ", Comps[1].TypedText);
> > > > >   EXPECT_EQ("let", Comps[1].DisplayText);
> > > > >   EXPECT_EQ("match ", Comps[2].TypedText);
> > > > >   EXPECT_EQ("match", Comps[2].DisplayText);
> > > > >   EXPECT_EQ("set ", Comps[3].TypedText);
> > > > >   EXPECT_EQ("set", Comps[3].DisplayText);
> > > > >   EXPECT_EQ("unlet ", Comps[4].TypedText);
> > > > >   EXPECT_EQ("unlet", Comps[4].DisplayText);
> > > > >   EXPECT_EQ("quit", Comps[5].DisplayText);
> > > > >   EXPECT_EQ("quit ", Comps[5].TypedText);
> > > > > 
> > > > >   Comps = QueryParser::complete("set o", 5, QS);
> > > > >   ASSERT_EQ(1u, Comps.size());
> > > > >   EXPECT_EQ("utput ", Comps[0].TypedText);
> > > > >   EXPECT_EQ("output", Comps[0].DisplayText);
> > > > > 
> > > > >   Comps = QueryParser::complete("match while", 11, QS);
> > > > >   ASSERT_EQ(1u, Comps.size());
> > > > >   EXPECT_EQ("Stmt(", Comps[0].TypedText);
> > > > >   EXPECT_EQ("Matcher<Stmt> whileStmt(Matcher<WhileStmt>...)",
> > > > >             Comps[0].DisplayText);
> > > > > }
> > > > > ```
> > > > > 
> > > > > This is an actual piece of code from `extra/unittests/clang-query/QueryParserTest.cpp`. Yes, it is a test, but it still is a nice example of how many macros can be found in code (especially if we are talking about pure C or some weird C++).
> > > > > 
> > > > > Thus, I think it is reasonable to treat macro invocation as a `1`-"complexity" node.
> > > > This "0" is not for the macro itself, but for the statements into which it expands. Macro itself is not a statement. If we put "1" here, it would produce a lot more complexity than you want.
> > > > 
> > > > That said, it's a good idea to treat every macro as a "complexity-1" statement, just need to figure out how to implement that correctly :)
> > > > 
> > > > Perhaps scan the source range of the sequence for how many different macro expansions are included, and add that number to complexity(?)
> > > > This "0" is not for the macro itself, but for the statements into which it expands. Macro itself is not a statement. If we put "1" here, it would produce a lot more complexity than you want.
> > > 
> > > Sure, I understand that, this is why I didn't suggest putting `1` there.
> > > 
> > > > Perhaps scan the source range of the sequence for how many different macro expansions are included, and add that number to complexity(?)
> > > 
> > > Yes, this is exactly the solution that would work. Since macros aren't in the AST we'd need to get through SourceRange anyway.
> > Though, it has to be optimized in order to prevent parsing a SourceLocation multiple times.
> *visiting each SourceLocation
Yeah, as a rough approximation we could count macro expansions within the current statement's children...

================
Comment at: test/Analysis/copypaste/macro-complexity.cpp:19
@@ +18,3 @@
+// Prevents that this tests won't accidentially pass because the code inside
+// the macro isn't complex enough.
+int foo(int a, int b) {  // expected-warning{{Detected code clone.}}
----------------
v.g.vassilev wrote:
> I am not sure I understand this comment. Could you reword?
Without macros, the same code would constitute a complex clone.
Wrapping code into macros reduces complexity of the code.
This tests the test above.

^(tried out some reword-ings)


https://reviews.llvm.org/D23316