[PATCH] D116814: Accept string literal decay in conditional operator

[Elvis Stansvik via Phabricator via cfe-commits]

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Format code with git-clang-format


The cppcoreguidelines-pro-bounds-array-to-pointer-decay check currently accepts

  const char *b = i ? "foo" : "foobar";

but not

  const char *a = i ? "foo" : "bar";

This is because the AST is slightly different in the latter case (see https://godbolt.org/z/MkHVvs).

This fixes up the inconsistency by making it accept the latter form as well.

Fixes https://github.com/llvm/llvm-project/issues/31155.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116814

Files:
  clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
  clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
@@ -49,3 +49,14 @@
   void *a[2];
   f2(static_cast<void *const*>(a)); // OK, explicit cast
 }
+
+void issue31155(int i) {
+  const char *a = i ? "foo" : "bar";    // OK, decay string literal to pointer
+  const char *b = i ? "foo" : "foobar"; // OK, decay string literal to pointer
+
+  char arr[1];
+  const char *c = i ? arr : "bar";
+  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: do not implicitly decay an array into a pointer
+  const char *d = i ? "foo" : arr;
+  // CHECK-MESSAGES: :[[@LINE-1]]:31: warning: do not implicitly decay an array into a pointer
+}
Index: clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
+++ clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
@@ -54,13 +54,17 @@
   // 2) inside a range-for over an array
   // 3) if it converts a string literal to a pointer
   Finder->addMatcher(
-      traverse(TK_AsIs,
-               implicitCastExpr(
-                   unless(hasParent(arraySubscriptExpr())),
-                   unless(hasParentIgnoringImpCasts(explicitCastExpr())),
-                   unless(isInsideOfRangeBeginEndStmt()),
-                   unless(hasSourceExpression(ignoringParens(stringLiteral()))))
-                   .bind("cast")),
+      traverse(
+          TK_AsIs,
+          implicitCastExpr(
+              unless(hasParent(arraySubscriptExpr())),
+              unless(hasParentIgnoringImpCasts(explicitCastExpr())),
+              unless(isInsideOfRangeBeginEndStmt()),
+              unless(hasSourceExpression(ignoringParens(stringLiteral()))),
+              unless(hasSourceExpression(ignoringParens(conditionalOperator(
+                  allOf(hasTrueExpression(stringLiteral()),
+                        hasFalseExpression(stringLiteral())))))))
+              .bind("cast")),
       this);
 }
 


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