[PATCH] D80603: add isAtPosition narrowing matcher for parmVarDecl

[Vy Nguyen via Phabricator via cfe-commits]

oontvoo created this revision.
Herald added subscribers: cfe-commits, danielkiss, kristof.beyls.
Herald added a project: clang.
oontvoo added reviewers: gribozavr, ymandel.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80603

Files:
  clang/include/clang/ASTMatchers/ASTMatchers.h
  clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp


Index: clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
===================================================================
--- clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -2643,6 +2643,13 @@
                       parmVarDecl(hasDefaultArgument())));
 }
 
+TEST(IsAtPosition, Basic) {
+  EXPECT_TRUE(matches("void x(int a) {}", parmVarDecl(isAtPosition(0))));
+  EXPECT_TRUE(matches("void x(int a, int b) {}", parmVarDecl(isAtPosition(1))));
+  EXPECT_TRUE(matches("void x(int a, int b) {}", parmVarDecl(isAtPosition(1))));
+  EXPECT_TRUE(notMatches("void x(int val) {}", parmVarDecl(isAtPosition(1))));
+}
+
 TEST(IsArray, Basic) {
   EXPECT_TRUE(matches("struct MyClass {}; MyClass *p1 = new MyClass[10];",
                       cxxNewExpr(isArray())));
Index: clang/include/clang/ASTMatchers/ASTMatchers.h
===================================================================
--- clang/include/clang/ASTMatchers/ASTMatchers.h
+++ clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -7001,6 +7001,26 @@
   return InnerMatcher.matches(Node, Finder, Builder);
 }
 
+/// Matches the ParmVarDecl nodes that are at the N'th position in the parameter
+/// list.
+///
+/// Given
+///
+/// \code
+/// void f(int a, int b, int c) {
+/// }
+/// \endcode
+///
+/// ``parmVarDecl(isAtPosition(0))``` matches `int a`.
+///
+/// ``parmVarDecl(isAtPosition(1))`` matches `int b`.
+AST_MATCHER_P(clang::ParmVarDecl, isAtPosition, unsigned, N) {
+  return parmVarDecl(hasAncestor(functionDecl(
+                         hasParameter(N, parmVarDecl().bind("this_decl")))),
+                     equalsBoundNode("this_decl"))
+      .matches(Node, Finder, Builder);
+}
+
 //----------------------------------------------------------------------------//
 // OpenMP handling.
 //----------------------------------------------------------------------------//


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