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[clang][Sema] Warn on self move for inlined static cast #76646

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Merged
merged 4 commits into from
Mar 6, 2024
Merged

[clang][Sema] Warn on self move for inlined static cast #76646

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a081f82
Warn on self move for inlined static cast
MaxEW707 Dec 31, 2023
ecd9d5b
use auto
MaxEW707 Dec 31, 2023
a02d21f
PR feedback on reducing logic
MaxEW707 Mar 6, 2024
bfaded8
Add unit tests that shouldn't warn
MaxEW707 Mar 6, 2024
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19 changes: 9 additions & 10 deletions clang/lib/Sema/SemaChecking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18843,18 +18843,17 @@ void Sema::DiagnoseSelfMove(const Expr *LHSExpr, const Expr *RHSExpr,
LHSExpr = LHSExpr->IgnoreParenImpCasts();
RHSExpr = RHSExpr->IgnoreParenImpCasts();

// Check for a call expression
const CallExpr *CE = dyn_cast<CallExpr>(RHSExpr);
if (!CE || CE->getNumArgs() != 1)
return;

// Check for a call to std::move
if (!CE->isCallToStdMove())
// Check for a call to std::move or for a static_cast<T&&>(..) to an xvalue
// which we can treat as an inlined std::move
if (const auto *CE = dyn_cast<CallExpr>(RHSExpr);
CE && CE->getNumArgs() == 1 && CE->isCallToStdMove())
RHSExpr = CE->getArg(0);
else if (const auto *CXXSCE = dyn_cast<CXXStaticCastExpr>(RHSExpr);
CXXSCE && CXXSCE->isXValue())
RHSExpr = CXXSCE->getSubExpr();
else
return;

// Get argument from std::move
RHSExpr = CE->getArg(0);

const DeclRefExpr *LHSDeclRef = dyn_cast<DeclRefExpr>(LHSExpr);
const DeclRefExpr *RHSDeclRef = dyn_cast<DeclRefExpr>(RHSExpr);

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15 changes: 15 additions & 0 deletions clang/test/SemaCXX/warn-self-move.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,9 @@ void int_test() {
x = std::move(x); // expected-warning{{explicitly moving}}
(x) = std::move(x); // expected-warning{{explicitly moving}}

x = static_cast<int&&>(x); // expected-warning{{explicitly moving}}
(x) = static_cast<int&&>(x); // expected-warning{{explicitly moving}}

using std::move;
x = move(x); // expected-warning{{explicitly moving}} \
expected-warning {{unqualified call to 'std::move}}
Expand All @@ -26,6 +29,9 @@ void global_int_test() {
global = std::move(global); // expected-warning{{explicitly moving}}
(global) = std::move(global); // expected-warning{{explicitly moving}}

global = static_cast<int&&>(global); // expected-warning{{explicitly moving}}
(global) = static_cast<int&&>(global); // expected-warning{{explicitly moving}}

using std::move;
global = move(global); // expected-warning{{explicitly moving}} \
expected-warning {{unqualified call to 'std::move}}
Expand All @@ -35,11 +41,16 @@ class field_test {
int x;
field_test(field_test&& other) {
x = std::move(x); // expected-warning{{explicitly moving}}
x = static_cast<int&&>(x); // expected-warning{{explicitly moving}}
x = std::move(other.x);
x = static_cast<int&&>(other.x);
other.x = std::move(x);
other.x = static_cast<int&&>(x);
other.x = std::move(other.x); // expected-warning{{explicitly moving}}
other.x = static_cast<int&&>(other.x); // expected-warning{{explicitly moving}}
}
void withSuggest(int x) {
x = static_cast<int&&>(x); // expected-warning{{explicitly moving variable of type 'int' to itself; did you mean to move to member 'x'?}}
x = std::move(x); // expected-warning{{explicitly moving variable of type 'int' to itself; did you mean to move to member 'x'?}}
}
};
Expand All @@ -50,11 +61,15 @@ struct C { C() {}; ~C() {} };
void struct_test() {
A a;
a = std::move(a); // expected-warning{{explicitly moving}}
a = static_cast<A&&>(a); // expected-warning{{explicitly moving}}

B b;
b = std::move(b); // expected-warning{{explicitly moving}}
b = static_cast<B&&>(b); // expected-warning{{explicitly moving}}
b.a = std::move(b.a); // expected-warning{{explicitly moving}}
b.a = static_cast<A&&>(b.a); // expected-warning{{explicitly moving}}

C c;
c = std::move(c); // expected-warning{{explicitly moving}}
c = static_cast<C&&>(c); // expected-warning{{explicitly moving}}
}