[clang-tools-extra] [clang-tidy] Add new check 'readability-inconsistent-ifelse-braces' (PR #162361)

[Davide Cunial via cfe-commits]

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@@ -0,0 +1,91 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "InconsistentIfElseBracesCheck.h"
+#include "../utils/BracesAroundStatement.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Stmt.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+/// Check that at least one branch of the \p If statement is a \c CompoundStmt.
+static bool shouldHaveBraces(const IfStmt *If) {
+  const Stmt *const Then = If->getThen();
+  if (isa<CompoundStmt>(Then))
+    return true;
+
+  if (const Stmt *const Else = If->getElse()) {
+    if (const auto *NestedIf = dyn_cast<const IfStmt>(Else))
+      return shouldHaveBraces(NestedIf);
+
+    return isa<CompoundStmt>(Else);
+  }
+
+  return false;
+}
+
+void InconsistentIfElseBracesCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      ifStmt(hasElse(anything()),
+             unless(isConsteval()), // 'if consteval' always has braces
+             unless(hasParent(ifStmt())))
+          .bind("if_stmt"),
+      this);
+}
+
+void InconsistentIfElseBracesCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *MatchedIf = Result.Nodes.getNodeAs<IfStmt>("if_stmt");
+  if (!shouldHaveBraces(MatchedIf))
+    return;
+  checkIfStmt(Result, MatchedIf);
+}
+
+void InconsistentIfElseBracesCheck::checkIfStmt(
+    const MatchFinder::MatchResult &Result, const IfStmt *If) {
+  const Stmt *Then = If->getThen();
+  if (const auto *NestedIf = dyn_cast<const IfStmt>(Then)) {
+    // If the then-branch is a nested IfStmt, first we need to add braces to
+    // it, then we need to check the inner IfStmt.
+    emitDiagnostic(Result, If->getThen(), If->getRParenLoc(), If->getElseLoc());
+
+    if (shouldHaveBraces(NestedIf))
+      checkIfStmt(Result, NestedIf);
+  } else if (!isa<CompoundStmt>(Then)) {
+    emitDiagnostic(Result, Then, If->getRParenLoc(), If->getElseLoc());
+  }
+
+  if (const Stmt *const Else = If->getElse()) {
+    if (const auto *NestedIf = dyn_cast<const IfStmt>(Else))
+      checkIfStmt(Result, NestedIf);
+    else if (!isa<CompoundStmt>(Else))
+      emitDiagnostic(Result, If->getElse(), If->getElseLoc());
+  }
+}
+
+void InconsistentIfElseBracesCheck::emitDiagnostic(
+    const MatchFinder::MatchResult &Result, const Stmt *S,
+    SourceLocation StartLoc, SourceLocation EndLocHint) {
+  if (StartLoc.isMacroID()) {
+    diag(StartLoc, "statement should have braces") << StartLoc.isMacroID();
----------------
capitan-davide wrote:

fixed

https://github.com/llvm/llvm-project/pull/162361