r366698 - [clangd] Add dlog()s for SelectionTree, enabling -debug-only=SelectionTree.cpp

[Sam McCall via cfe-commits]

Author: sammccall
Date: Mon Jul 22 08:55:53 2019
New Revision: 366698

URL: http://llvm.org/viewvc/llvm-project?rev=366698&view=rev
Log:
[clangd] Add dlog()s for SelectionTree, enabling -debug-only=SelectionTree.cpp

Summary:
SelectionTree is a RecursiveASTVisitor which processes getSourceRange() for
every node. This is a lot of surface area with the AST, as getSourceRange()
is specialized for *many* node types.
And the resulting SelectionTree depends on the source ranges of many
visited nodes, and the order of traversal.

Put together, this means we really need a traversal log to debug when we
get an unexpected SelectionTree. I've built this ad-hoc a few times, now
it's time to check it in.

Example output:
```
D[14:07:44.184] Computing selection for </usr/local/google/home/sammccall/test.cc:1:7, col:8>
D[14:07:44.184]  push: VarDecl const auto x = 42
D[14:07:44.184]   claimRange: </usr/local/google/home/sammccall/test.cc:1:12, col:13>
D[14:07:44.184]   push: NestedNameSpecifierLoc (empty NestedNameSpecifierLoc)
D[14:07:44.184]   pop: NestedNameSpecifierLoc (empty NestedNameSpecifierLoc)
D[14:07:44.184]   push: QualifiedTypeLoc const auto
D[14:07:44.184]   pop: QualifiedTypeLoc const auto
D[14:07:44.184]    claimRange: </usr/local/google/home/sammccall/test.cc:1:7, col:11>
D[14:07:44.184]    hit selection: </usr/local/google/home/sammccall/test.cc:1:7, col:8>
D[14:07:44.184]   skip: IntegerLiteral 42
D[14:07:44.184]    skipped range = </usr/local/google/home/sammccall/test.cc:1:16>
D[14:07:44.184]  pop: VarDecl const auto x = 42
D[14:07:44.184]   claimRange: </usr/local/google/home/sammccall/test.cc:1:1, col:18>
D[14:07:44.184]  skip: VarDecl int y = 43
D[14:07:44.184]   skipped range = </usr/local/google/home/sammccall/test.cc:2:1, col:9>
D[14:07:44.184] Built selection tree
TranslationUnitDecl
  VarDecl const auto x = 42
     .QualifiedTypeLoc const auto

```

Reviewers: hokein

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65073

Modified:
    cfe/trunk/lib/AST/ASTTypeTraits.cpp

Modified: cfe/trunk/lib/AST/ASTTypeTraits.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ASTTypeTraits.cpp?rev=366698&r1=366697&r2=366698&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ASTTypeTraits.cpp (original)
+++ cfe/trunk/lib/AST/ASTTypeTraits.cpp Mon Jul 22 08:55:53 2019
@@ -15,6 +15,7 @@
 #include "clang/AST/ASTTypeTraits.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclCXX.h"
+#include "clang/AST/NestedNameSpecifier.h"
 
 namespace clang {
 namespace ast_type_traits {
@@ -129,9 +130,12 @@ void DynTypedNode::print(llvm::raw_ostre
     TN->print(OS, PP);
   else if (const NestedNameSpecifier *NNS = get<NestedNameSpecifier>())
     NNS->print(OS, PP);
-  else if (const NestedNameSpecifierLoc *NNSL = get<NestedNameSpecifierLoc>())
-    NNSL->getNestedNameSpecifier()->print(OS, PP);
-  else if (const QualType *QT = get<QualType>())
+  else if (const NestedNameSpecifierLoc *NNSL = get<NestedNameSpecifierLoc>()) {
+    if (const NestedNameSpecifier *NNS = NNSL->getNestedNameSpecifier())
+      NNS->print(OS, PP);
+    else
+      OS << "(empty NestedNameSpecifierLoc)";
+  } else if (const QualType *QT = get<QualType>())
     QT->print(OS, PP);
   else if (const TypeLoc *TL = get<TypeLoc>())
     TL->getType().print(OS, PP);