[clang-tools-extra] [clang-tidy] Enhance modernize-use-starts-ends-with to handle substr patterns (PR #116033)

[Nicolas van Kempen via cfe-commits]

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@@ -30,6 +30,17 @@ struct NotLengthExprForStringNode {
                IntegerLiteralSizeNode->getValue().getZExtValue();
       }
 
+      if (const auto *DeclRefNode = Node.get<DeclRefExpr>()) {
+        if (const auto *VD = dyn_cast<VarDecl>(DeclRefNode->getDecl())) {
+          if (VD->hasInit() && VD->getType().isConstQualified()) {
+            if (const auto *Init = dyn_cast<IntegerLiteral>(VD->getInit())) {
+              return StringLiteralNode->getLength() !=
+                     Init->getValue().getZExtValue();
+            }
+          }
+        }
+      }
+
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nicovank wrote:

I'm not sure exactly, what case is this adding? IMO changing `lengthExprForStringNode` can/should happen in subsequent PR; it affects existing `compare`/`find`/`rfind` branches as well.

https://github.com/llvm/llvm-project/pull/116033