[PATCH] D146887: [clang-tidy] Fix if-constexpr false-positive in readability-misleading-indentation

[Piotr Zegar via Phabricator via cfe-commits]

PiotrZSL created this revision.
Herald added subscribers: carlosgalvezp, xazax.hun.
Herald added a reviewer: njames93.
Herald added a project: All.
PiotrZSL requested review of this revision.
Herald added a project: clang-tools-extra.
Herald added a subscriber: cfe-commits.

When  depend on template parameter,
compiler can use NullStmt instead of CompoundStmt.
This causes issues as we losing information about
end location of that Stmt. To avoid this issue
check now ignores ifStmt with NullStmt on true-branch.

Fixes: https://github.com/llvm/llvm-project/issues/61435


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146887

Files:
  clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
  clang-tools-extra/docs/ReleaseNotes.rst
  clang-tools-extra/test/clang-tidy/checkers/readability/misleading-indentation.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/readability/misleading-indentation.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/readability/misleading-indentation.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/readability/misleading-indentation.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s readability-misleading-indentation %t -- -- -fno-delayed-template-parsing
+// RUN: %check_clang_tidy -std=c++17-or-later %s readability-misleading-indentation %t -- -- -fno-delayed-template-parsing
 
 void foo1();
 void foo2();
@@ -195,3 +195,31 @@
   mustFail<true>();
   mustFail<false>();
 }
+
+namespace PR61435 {
+
+template<int N>
+constexpr auto lam_correct = []{
+  if constexpr (N == 1) {
+  } else {
+  }
+};
+
+template<int N>
+constexpr auto lam_incorrect = []{
+  if constexpr (N == 1) {
+  }
+   else {
+  }
+  // CHECK-MESSAGES: :[[@LINE-2]]:4: warning: different indentation for 'if' and corresponding 'else' [readability-misleading-indentation]
+};
+
+void test() {
+  lam_correct<1>();
+  lam_correct<2>();
+
+  lam_incorrect<1>();
+  lam_incorrect<2>();
+}
+
+}
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -225,6 +225,10 @@
   magic numbers in type aliases such as ``using`` and ``typedef`` declarations if
   the new ``IgnoreTypeAliases`` option is set to true.
 
+- Fixed a false positive in :doc:`readability-misleading-indentation
+  <clang-tidy/checks/readability/misleading-indentation>` check when warning would
+  be unnecessarily emitted for template dependent ``if constexpr``.
+
 - Fixed a false positive in :doc:`cppcoreguidelines-slicing
   <clang-tidy/checks/cppcoreguidelines/slicing>` check when warning would be
   emitted in constructor for virtual base class initialization.
Index: clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
+++ clang-tools-extra/clang-tidy/readability/MisleadingIndentationCheck.cpp
@@ -104,7 +104,8 @@
 }
 
 void MisleadingIndentationCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(ifStmt(hasElse(stmt())).bind("if"), this);
+  Finder->addMatcher(
+      ifStmt(unless(hasThen(nullStmt())), hasElse(stmt())).bind("if"), this);
   Finder->addMatcher(
       compoundStmt(has(stmt(anyOf(ifStmt(), forStmt(), whileStmt()))))
           .bind("compound"),


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D146887.508346.patch
Type: text/x-patch
Size: 2640 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20230325/6501917c/attachment.bin>