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

[Artem Dergachev via cfe-commits]

NoQ added inline comments.

================
Comment at: lib/Analysis/CloneDetection.cpp:436
@@ +435,3 @@
+    if (IsInMacro) {
+      Signature.Complexity = 0;
+    }
----------------
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(?)


https://reviews.llvm.org/D23316