Izaron created this revision.
Izaron added reviewers: hokein, njames93, aaron.ballman.
Herald added subscribers: carlosgalvezp, xazax.hun.
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Izaron requested review of this revision.
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Herald added a subscriber: cfe-commits.

The checker should ignore requirement expressions inside concept
definitions, because redundant expressions still make sense here

Fixes https://github.com/llvm/llvm-project/issues/54114


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D122078

Files:
  clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
  clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp

Index: clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/misc-redundant-expression.cpp
@@ -1,4 +1,4 @@
-// RUN: %check_clang_tidy %s misc-redundant-expression %t -- -- -fno-delayed-template-parsing
+// RUN: %check_clang_tidy %s misc-redundant-expression -std=c++20 %t -- -- -fno-delayed-template-parsing
 
 typedef __INT64_TYPE__ I64;
 
@@ -807,3 +807,13 @@
 };
 
 } // namespace no_crash
+
+namespace concepts {
+// redundant expressions inside concepts make sense, ignore them
+template <class I>
+concept TestConcept = requires(I i) {
+  {i - i};
+  {i && i};
+  {i ? i : i};
+};
+} // namespace concepts
Index: clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
+++ clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp
@@ -10,6 +10,7 @@
 #include "../utils/Matchers.h"
 #include "../utils/OptionsUtils.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/ExprConcepts.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
@@ -438,6 +439,8 @@
   return Node.isIntegerConstantExpr(Finder->getASTContext());
 }
 
+AST_MATCHER(Expr, isRequiresExpr) { return isa<RequiresExpr>(Node); }
+
 AST_MATCHER(BinaryOperator, operandsAreEquivalent) {
   return areEquivalentExpr(Node.getLHS(), Node.getRHS());
 }
@@ -831,6 +834,7 @@
 
   const auto BannedIntegerLiteral =
       integerLiteral(expandedByMacro(KnownBannedMacroNames));
+  const auto BannedAncestor = expr(isRequiresExpr());
 
   // Binary with equivalent operands, like (X != 2 && X != 2).
   Finder->addMatcher(
@@ -846,7 +850,8 @@
                    unless(hasType(realFloatingPointType())),
                    unless(hasEitherOperand(hasType(realFloatingPointType()))),
                    unless(hasLHS(AnyLiteralExpr)),
-                   unless(hasDescendant(BannedIntegerLiteral)))
+                   unless(hasDescendant(BannedIntegerLiteral)),
+                   unless(hasAncestor(BannedAncestor)))
                    .bind("binary")),
       this);
 
@@ -859,7 +864,8 @@
                      unless(isInTemplateInstantiation()),
                      unless(binaryOperatorIsInMacro()),
                      // TODO: if the banned macros are themselves duplicated
-                     unless(hasDescendant(BannedIntegerLiteral)))
+                     unless(hasDescendant(BannedIntegerLiteral)),
+                     unless(hasAncestor(BannedAncestor)))
           .bind("nested-duplicates"),
       this);
 
@@ -869,7 +875,8 @@
                conditionalOperator(expressionsAreEquivalent(),
                                    // Filter noisy false positives.
                                    unless(conditionalOperatorIsInMacro()),
-                                   unless(isInTemplateInstantiation()))
+                                   unless(isInTemplateInstantiation()),
+                                   unless(hasAncestor(BannedAncestor)))
                    .bind("cond")),
       this);
 
@@ -882,7 +889,8 @@
                                                 ">=", "&&", "||", "="),
                    parametersAreEquivalent(),
                    // Filter noisy false positives.
-                   unless(isMacro()), unless(isInTemplateInstantiation()))
+                   unless(isMacro()), unless(isInTemplateInstantiation()),
+                   unless(hasAncestor(BannedAncestor)))
                    .bind("call")),
       this);
 
@@ -892,7 +900,8 @@
           hasAnyOverloadedOperatorName("|", "&", "||", "&&", "^"),
           nestedParametersAreEquivalent(), argumentCountIs(2),
           // Filter noisy false positives.
-          unless(isMacro()), unless(isInTemplateInstantiation()))
+          unless(isMacro()), unless(isInTemplateInstantiation()),
+          unless(hasAncestor(BannedAncestor)))
           .bind("nested-duplicates"),
       this);
 
@@ -909,7 +918,8 @@
                                    binaryOperator(hasAnyOperatorName("|", "&")),
                                    integerLiteral())),
                                hasRHS(integerLiteral())))))
-                           .bind("logical-bitwise-confusion")))),
+                           .bind("logical-bitwise-confusion")),
+                   unless(hasAncestor(BannedAncestor)))),
       this);
 
   // Match expressions like: (X << 8) & 0xFF
@@ -922,7 +932,8 @@
                                    hasRHS(ignoringParenImpCasts(
                                        integerLiteral().bind("shift-const"))))),
                                ignoringParenImpCasts(
-                                   integerLiteral().bind("and-const"))))
+                                   integerLiteral().bind("and-const"))),
+                   unless(hasAncestor(BannedAncestor)))
                    .bind("left-right-shift-confusion")),
       this);
 
@@ -940,7 +951,8 @@
   // Match expressions like: x <op> 0xFF == 0xF00.
   Finder->addMatcher(
       traverse(TK_AsIs, binaryOperator(isComparisonOperator(),
-                                       hasOperands(BinOpCstLeft, CstRight))
+                                       hasOperands(BinOpCstLeft, CstRight),
+                                       unless(hasAncestor(BannedAncestor)))
                             .bind("binop-const-compare-to-const")),
       this);
 
@@ -950,7 +962,8 @@
           TK_AsIs,
           binaryOperator(isComparisonOperator(),
                          anyOf(allOf(hasLHS(BinOpCstLeft), hasRHS(SymRight)),
-                               allOf(hasLHS(SymRight), hasRHS(BinOpCstLeft))))
+                               allOf(hasLHS(SymRight), hasRHS(BinOpCstLeft))),
+                         unless(hasAncestor(BannedAncestor)))
               .bind("binop-const-compare-to-sym")),
       this);
 
@@ -960,7 +973,8 @@
                binaryOperator(isComparisonOperator(), hasLHS(BinOpCstLeft),
                               hasRHS(BinOpCstRight),
                               // Already reported as redundant.
-                              unless(operandsAreEquivalent()))
+                              unless(operandsAreEquivalent()),
+                              unless(hasAncestor(BannedAncestor)))
                    .bind("binop-const-compare-to-binop-const")),
       this);
 
@@ -976,7 +990,8 @@
                binaryOperator(hasAnyOperatorName("||", "&&"),
                               hasLHS(ComparisonLeft), hasRHS(ComparisonRight),
                               // Already reported as redundant.
-                              unless(operandsAreEquivalent()))
+                              unless(operandsAreEquivalent()),
+                              unless(hasAncestor(BannedAncestor)))
                    .bind("comparisons-of-symbol-and-const")),
       this);
 }
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