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Fixing issue "incorrect -Winfinite-recursion warning on potentially-unevaluated
operand #21668”
By having dedicated visit function (`VisitCXXTypeidExpr`) for `typeid`, instead
of using default (`VisitStmt`).
In this new function we skip over CFG build for unevaluated operands of `typeid`
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D128747
Files:
clang/lib/Analysis/CFG.cpp
clang/test/SemaCXX/warn-infinite-recursion.cpp
Index: clang/test/SemaCXX/warn-infinite-recursion.cpp
===================================================================
--- clang/test/SemaCXX/warn-infinite-recursion.cpp
+++ clang/test/SemaCXX/warn-infinite-recursion.cpp
@@ -1,5 +1,7 @@
// RUN: %clang_cc1 %s -fsyntax-only -verify -Winfinite-recursion
+#include <typeinfo>
+
void a() { // expected-warning{{call itself}}
a();
}
@@ -171,3 +173,18 @@
}
int wrapper_sum = test_wrapper<2>(); // expected-note{{instantiation}}
+
+struct Q {
+ virtual ~Q(){};
+};
+
+Q q;
+Q &evaluated_recursive_function(int x) {
+ typeid(evaluated_recursive_function(x));
+ return q;
+}
+
+int unevaluated_recursive_function() {
+ typeid(unevaluated_recursive_function());
+ return 0;
+}
\ No newline at end of file
Index: clang/lib/Analysis/CFG.cpp
===================================================================
--- clang/lib/Analysis/CFG.cpp
+++ clang/lib/Analysis/CFG.cpp
@@ -564,6 +564,7 @@
AddStmtChoice asc);
CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T);
CFGBlock *VisitCXXTryStmt(CXXTryStmt *S);
+ CFGBlock *VisitCXXTypeidExpr(CXXTypeidExpr *S, AddStmtChoice asc);
CFGBlock *VisitDeclStmt(DeclStmt *DS);
CFGBlock *VisitDeclSubExpr(DeclStmt *DS);
CFGBlock *VisitDefaultStmt(DefaultStmt *D);
@@ -2220,6 +2221,9 @@
case Stmt::CXXTryStmtClass:
return VisitCXXTryStmt(cast<CXXTryStmt>(S));
+ case Stmt::CXXTypeidExprClass:
+ return VisitCXXTypeidExpr(cast<CXXTypeidExpr>(S), asc);
+
case Stmt::CXXForRangeStmtClass:
return VisitCXXForRangeStmt(cast<CXXForRangeStmt>(S));
@@ -4045,6 +4049,28 @@
return VisitStmt(T, AddStmtChoice::AlwaysAdd);
}
+CFGBlock *CFGBuilder::VisitCXXTypeidExpr(CXXTypeidExpr *S, AddStmtChoice asc) {
+ if (asc.alwaysAdd(*this, S)) {
+ autoCreateBlock();
+ appendStmt(Block, S);
+ }
+
+ // C++ [expr.typeid]p3:
+ // When typeid is applied to an expression other than an glvalue of a
+ // polymorphic class type [...] [the] expression is an unevaluated
+ // operand. [...]
+ // We add only potentially evaluated statements to block to avoid
+ // CFG generation for unevaluated operands.
+ if (S && !S->isTypeDependent()) {
+ if (S->isPotentiallyEvaluated()) {
+ return VisitChildren(S);
+ }
+ }
+
+ // Return block without CFG for unevaluated operands.
+ return Block;
+}
+
CFGBlock *CFGBuilder::VisitDoStmt(DoStmt *D) {
CFGBlock *LoopSuccessor = nullptr;
Index: clang/test/SemaCXX/warn-infinite-recursion.cpp
===================================================================
--- clang/test/SemaCXX/warn-infinite-recursion.cpp
+++ clang/test/SemaCXX/warn-infinite-recursion.cpp
@@ -1,5 +1,7 @@
// RUN: %clang_cc1 %s -fsyntax-only -verify -Winfinite-recursion
+#include <typeinfo>
+
void a() { // expected-warning{{call itself}}
a();
}
@@ -171,3 +173,18 @@
}
int wrapper_sum = test_wrapper<2>(); // expected-note{{instantiation}}
+
+struct Q {
+ virtual ~Q(){};
+};
+
+Q q;
+Q &evaluated_recursive_function(int x) {
+ typeid(evaluated_recursive_function(x));
+ return q;
+}
+
+int unevaluated_recursive_function() {
+ typeid(unevaluated_recursive_function());
+ return 0;
+}
\ No newline at end of file
Index: clang/lib/Analysis/CFG.cpp
===================================================================
--- clang/lib/Analysis/CFG.cpp
+++ clang/lib/Analysis/CFG.cpp
@@ -564,6 +564,7 @@
AddStmtChoice asc);
CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T);
CFGBlock *VisitCXXTryStmt(CXXTryStmt *S);
+ CFGBlock *VisitCXXTypeidExpr(CXXTypeidExpr *S, AddStmtChoice asc);
CFGBlock *VisitDeclStmt(DeclStmt *DS);
CFGBlock *VisitDeclSubExpr(DeclStmt *DS);
CFGBlock *VisitDefaultStmt(DefaultStmt *D);
@@ -2220,6 +2221,9 @@
case Stmt::CXXTryStmtClass:
return VisitCXXTryStmt(cast<CXXTryStmt>(S));
+ case Stmt::CXXTypeidExprClass:
+ return VisitCXXTypeidExpr(cast<CXXTypeidExpr>(S), asc);
+
case Stmt::CXXForRangeStmtClass:
return VisitCXXForRangeStmt(cast<CXXForRangeStmt>(S));
@@ -4045,6 +4049,28 @@
return VisitStmt(T, AddStmtChoice::AlwaysAdd);
}
+CFGBlock *CFGBuilder::VisitCXXTypeidExpr(CXXTypeidExpr *S, AddStmtChoice asc) {
+ if (asc.alwaysAdd(*this, S)) {
+ autoCreateBlock();
+ appendStmt(Block, S);
+ }
+
+ // C++ [expr.typeid]p3:
+ // When typeid is applied to an expression other than an glvalue of a
+ // polymorphic class type [...] [the] expression is an unevaluated
+ // operand. [...]
+ // We add only potentially evaluated statements to block to avoid
+ // CFG generation for unevaluated operands.
+ if (S && !S->isTypeDependent()) {
+ if (S->isPotentiallyEvaluated()) {
+ return VisitChildren(S);
+ }
+ }
+
+ // Return block without CFG for unevaluated operands.
+ return Block;
+}
+
CFGBlock *CFGBuilder::VisitDoStmt(DoStmt *D) {
CFGBlock *LoopSuccessor = nullptr;
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