[clang][transformer] Introduce a constructExprArgs range selector. (llvm#95901)

This is similar to `callArgs` but for construct exprs like `S(42)` or
`{42}`.

Author: legrosbuffle

clang/include/clang/Tooling/Transformer/RangeSelector.h

@@ -86,6 +86,11 @@ RangeSelector name(std::string ID);
 // source between the call's parentheses).
 RangeSelector callArgs(std::string ID);
 
+// Given a \c CXXConstructExpr (bound to \p ID), selects the
+// arguments' source text. Depending on the syntactic form of the construct,
+// this is the range between parentheses or braces.
+RangeSelector constructExprArgs(std::string ID);
+
 // Given a \c CompoundStmt (bound to \p ID), selects the source of the
 // statements (all source between the braces).
 RangeSelector statements(std::string ID);

clang/lib/Tooling/Transformer/RangeSelector.cpp

@@ -96,13 +96,6 @@ static SourceLocation findPreviousTokenKind(SourceLocation Start,
   }
 }
 
-static SourceLocation findOpenParen(const CallExpr &E, const SourceManager &SM,
-                                    const LangOptions &LangOpts) {
-  SourceLocation EndLoc =
-      E.getNumArgs() == 0 ? E.getRParenLoc() : E.getArg(0)->getBeginLoc();
-  return findPreviousTokenKind(EndLoc, SM, LangOpts, tok::TokenKind::l_paren);
-}
-
 RangeSelector transformer::before(RangeSelector Selector) {
   return [Selector](const MatchResult &Result) -> Expected<CharSourceRange> {
     Expected<CharSourceRange> SelectedRange = Selector(Result);
@@ -287,18 +280,50 @@ RangeSelector transformer::statements(std::string ID) {
 }
 
 namespace {
-// Returns the range of the source between the call's parentheses.
-CharSourceRange getCallArgumentsRange(const MatchResult &Result,
-                                      const CallExpr &CE) {
+
+SourceLocation getRLoc(const CallExpr &E) { return E.getRParenLoc(); }
+
+SourceLocation getRLoc(const CXXConstructExpr &E) {
+  return E.getParenOrBraceRange().getEnd();
+}
+
+tok::TokenKind getStartToken(const CallExpr &E) {
+  return tok::TokenKind::l_paren;
+}
+
+tok::TokenKind getStartToken(const CXXConstructExpr &E) {
+  return isa<CXXTemporaryObjectExpr>(E) ? tok::TokenKind::l_paren
+                                        : tok::TokenKind::l_brace;
+}
+
+template <typename ExprWithArgs>
+SourceLocation findArgStartDelimiter(const ExprWithArgs &E, SourceLocation RLoc,
+                                     const SourceManager &SM,
+                                     const LangOptions &LangOpts) {
+  SourceLocation Loc = E.getNumArgs() == 0 ? RLoc : E.getArg(0)->getBeginLoc();
+  return findPreviousTokenKind(Loc, SM, LangOpts, getStartToken(E));
+}
+// Returns the range of the source between the call's or construct expr's
+// parentheses/braces.
+template <typename ExprWithArgs>
+CharSourceRange getArgumentsRange(const MatchResult &Result,
+                                  const ExprWithArgs &CE) {
+  const SourceLocation RLoc = getRLoc(CE);
   return CharSourceRange::getCharRange(
-      findOpenParen(CE, *Result.SourceManager, Result.Context->getLangOpts())
+      findArgStartDelimiter(CE, RLoc, *Result.SourceManager,
+                            Result.Context->getLangOpts())
           .getLocWithOffset(1),
-      CE.getRParenLoc());
+      RLoc);
 }
 } // namespace
 
 RangeSelector transformer::callArgs(std::string ID) {
-  return RelativeSelector<CallExpr, getCallArgumentsRange>(std::move(ID));
+  return RelativeSelector<CallExpr, getArgumentsRange<CallExpr>>(std::move(ID));
+}
+
+RangeSelector transformer::constructExprArgs(std::string ID) {
+  return RelativeSelector<CXXConstructExpr,
+                          getArgumentsRange<CXXConstructExpr>>(std::move(ID));
 }
 
 namespace {

clang/unittests/Tooling/RangeSelectorTest.cpp

@@ -651,6 +651,48 @@ TEST(RangeSelectorTest, CallArgsErrors) {
                        Failed<StringError>(withTypeErrorMessage("stmt")));
 }
 
+TEST(RangeSelectorTest, ConstructExprArgs) {
+  const StringRef Code = R"cc(
+    struct C {
+      C(int, int);
+    };
+    C f() {
+      return C(1, 2);
+    }
+  )cc";
+  const char *ID = "id";
+  TestMatch Match = matchCode(Code, cxxTemporaryObjectExpr().bind(ID));
+  EXPECT_THAT_EXPECTED(select(constructExprArgs(ID), Match), HasValue("1, 2"));
+}
+
+TEST(RangeSelectorTest, ConstructExprBracedArgs) {
+  const StringRef Code = R"cc(
+    struct C {
+      C(int, int);
+    };
+    C f() {
+      return {1, 2};
+    }
+  )cc";
+  const char *ID = "id";
+  TestMatch Match = matchCode(Code, cxxConstructExpr().bind(ID));
+  EXPECT_THAT_EXPECTED(select(constructExprArgs(ID), Match), HasValue("1, 2"));
+}
+
+TEST(RangeSelectorTest, ConstructExprNoArgs) {
+  const StringRef Code = R"cc(
+    struct C {
+      C();
+    };
+    C f() {
+      return C();
+    }
+  )cc";
+  const char *ID = "id";
+  TestMatch Match = matchCode(Code, cxxTemporaryObjectExpr().bind(ID));
+  EXPECT_THAT_EXPECTED(select(constructExprArgs(ID), Match), HasValue(""));
+}
+
 TEST(RangeSelectorTest, StatementsOp) {
   StringRef Code = R"cc(
     void g();