[include-cleaner] Always treat constructor calls as implicit

Treating constructor calls when the type name isn't explicitly spelled
can cause spurious results, so turn them into implicit references.
This doesn't change the behaviour for constructor calls that explicitly spell
the type name, as we should see a reference through the typeloc.

Fixes llvm/llvm-project#60812

Differential Revision: https://reviews.llvm.org/D144582

Author: kadircet

clang-tools-extra/include-cleaner/lib/WalkAST.cpp

@@ -102,9 +102,12 @@ class ASTWalker : public RecursiveASTVisitor<ASTWalker> {
   }
 
   bool VisitCXXConstructExpr(CXXConstructExpr *E) {
+    // Always treat consturctor calls as implicit. We'll have an explicit
+    // reference for the constructor calls that mention the type-name (through
+    // TypeLocs). This reference only matters for cases where there's no
+    // explicit syntax at all or there're only braces.
     report(E->getLocation(), getMemberProvider(E->getType()),
-           E->getParenOrBraceRange().isValid() ? RefType::Explicit
-                                               : RefType::Implicit);
+           RefType::Implicit);
     return true;
   }
 

clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp

@@ -111,6 +111,9 @@ TEST(WalkAST, TagType) {
   testWalk("struct $explicit^S {};", "^S *y;");
   testWalk("enum $explicit^E {};", "^E *y;");
   testWalk("struct $explicit^S { static int x; };", "int y = ^S::x;");
+  // One explicit call from the TypeLoc in constructor spelling, another
+  // implicit reference through the constructor call.
+  testWalk("struct $explicit^$implicit^S { static int x; };", "auto y = ^S();");
 }
 
 TEST(WalkAST, Alias) {
@@ -241,7 +244,7 @@ TEST(WalkAST, MemberExprs) {
 TEST(WalkAST, ConstructExprs) {
   testWalk("struct $implicit^S {};", "S ^t;");
   testWalk("struct $implicit^S { S(); };", "S ^t;");
-  testWalk("struct $explicit^S { S(int); };", "S ^t(42);");
+  testWalk("struct $implicit^S { S(int); };", "S ^t(42);");
   testWalk("struct $implicit^S { S(int); };", "S t = ^42;");
   testWalk("namespace ns { struct S{}; } using ns::$implicit^S;", "S ^t;");
 }