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Remove warning in dead stores checker for 

dead stores within nested assignments.  I have
never seen an actual bug found by this specific
warning, and it can lead to many false positives.

llvm-svn: 123394
This commit is contained in:
Ted Kremenek 2011-01-13 20:58:56 +00:00
parent b084be90e8
commit f224820b45
2 changed files with 14 additions and 9 deletions
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11
clang/lib/StaticAnalyzer/Checkers/CheckDeadStores.cpp
View File

@ -1,4 +1,4 @@
//==- DeadStores.cpp - Check for stores to dead variables --------*- C++ -*-==//
//==- DeadStoresChecker.cpp - Check for stores to dead variables -*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
@ -70,11 +70,10 @@ public:
break;
case Enclosing:
BugType = "Dead nested assignment";
msg = "Although the value stored to '" + name +
"' is used in the enclosing expression, the value is never actually"
" read from '" + name + "'";
break;
// Don't report issues in this case, e.g.: "if (x = foo())",
// where 'x' is unused later. We have yet to see a case where
// this is a real bug.
return;
}
BR.EmitBasicReport(BugType, "Dead store", msg, L, R);

12
clang/test/Analysis/dead-stores.c
View File

@ -75,9 +75,11 @@ int f7d(int *p) {
return 1;
}
// Don't warn for dead stores in nested expressions. We have yet
// to see a real bug in this scenario.
int f8(int *p) {
extern int *baz();
if ((p = baz())) // expected-warning{{Although the value}}
if ((p = baz())) // no-warning
return 1;
return 0;
}
@ -148,9 +150,11 @@ void f15(unsigned x, unsigned y) {
int z[count]; // expected-warning{{unused variable 'z'}}
}
// Don't warn for dead stores in nested expressions. We have yet
// to see a real bug in this scenario.
int f16(int x) {
x = x * 2;
x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}} expected-warning{{The left operand to '*' is always 1}} expected-warning{{The left operand to '+' is always 0}}
x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{The left operand to '+' is always 0}} expected-warning{{The left operand to '*' is always 1}}
? 5 : 8;
return x;
}
@ -175,7 +179,9 @@ int f18() {
x = 10; // expected-warning{{Value stored to 'x' is never read}}
while (1);
return (x = 10); // expected-warning{{Although the value stored to 'x' is used in the enclosing expression, the value is never actually read from 'x'}}
// Don't warn for dead stores in nested expressions. We have yet
// to see a real bug in this scenario.
return (x = 10); // no-warning
}
// PR 3514: false positive `dead initialization` warning for init to global