[clang-tidy] Fix bugprone-argument-comment bug: negative literal number is not checked.

Summary:
For example:
```
void foo(int a);
foo(-2);
```
should be fixed as:
```
foo(/*a=*/-2);
```
This change tries to fix this issue.

Reviewers: alexfh, hokein, aaron.ballman

Reviewed By: alexfh, aaron.ballman

Subscribers: xazax.hun, cfe-commits

Tags: #clang, #clang-tools-extra

Patch by Yubo Xie.

Differential Revision: https://reviews.llvm.org/D67084

llvm-svn: 371072

1 files changed, 3 insertions, 1 deletions

diff --git a/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
index 07219f9c724..968333ce15e 100644
--- a/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/ArgumentCommentCheck.cpp
@@ -230,9 +230,11 @@ static const FunctionDecl *resolveMocks(const FunctionDecl *Func) {
 // Given the argument type and the options determine if we should
 // be adding an argument comment.
 bool ArgumentCommentCheck::shouldAddComment(const Expr *Arg) const {
+  Arg = Arg->IgnoreImpCasts();
+  if (isa<UnaryOperator>(Arg))
+    Arg = cast<UnaryOperator>(Arg)->getSubExpr();
   if (Arg->getExprLoc().isMacroID())
     return false;
-  Arg = Arg->IgnoreImpCasts();
   return (CommentBoolLiterals && isa<CXXBoolLiteralExpr>(Arg)) ||
          (CommentIntegerLiterals && isa<IntegerLiteral>(Arg)) ||
          (CommentFloatLiterals && isa<FloatingLiteral>(Arg)) ||