aaron.ballman created this revision.
aaron.ballman added reviewers: rsmith, rtrieu, dblaikie.
aaron.ballman added a subscriber: cfe-commits.
When performing an implicit from float to bool, the floating point value must
be *exactly* zero in order for the conversion to result in 0. This does not
involve a conversion through an integer value, and so truncation of the value
is not performed. This patch addresses this by using the floating-point value
when determining whether to print "true" or "false" in the diagnostic. The
behavior of the codegen has always been correct, so this only modifies the
wording of the diagnostic to be accurate.
This patch address PR25876.
http://reviews.llvm.org/D15814
Files:
lib/Sema/SemaChecking.cpp
test/SemaCXX/warn-literal-conversion.cpp
Index: test/SemaCXX/warn-literal-conversion.cpp
===================================================================
--- test/SemaCXX/warn-literal-conversion.cpp
+++ test/SemaCXX/warn-literal-conversion.cpp
@@ -38,3 +38,14 @@
int y = (24*60*60) * 0.25;
int pennies = 123.45 * 100;
}
+
+// Similarly, test floating point conversion to bool. Only float values of zero
+// are converted to false; everything else is converted to true.
+void test1() {
+ bool b1 = 0.99f; // expected-warning {{implicit conversion from 'float' to
'bool' changes value from 0.99 to true}}
+ bool b2 = 0.99; // expected-warning {{implicit conversion from 'double' to
'bool' changes value from 0.99 to true}}
+ // These do not warn because they can be directly converted to integral
+ // values.
+ bool b3 = 0.0f;
+ bool b4 = 0.0;
+}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -6983,7 +6983,7 @@
SmallString<16> PrettyTargetValue;
if (T->isSpecificBuiltinType(BuiltinType::Bool))
- PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
+ PrettyTargetValue = Value.isZero() ? "false" : "true";
else
IntegerValue.toString(PrettyTargetValue);
Index: test/SemaCXX/warn-literal-conversion.cpp
===================================================================
--- test/SemaCXX/warn-literal-conversion.cpp
+++ test/SemaCXX/warn-literal-conversion.cpp
@@ -38,3 +38,14 @@
int y = (24*60*60) * 0.25;
int pennies = 123.45 * 100;
}
+
+// Similarly, test floating point conversion to bool. Only float values of zero
+// are converted to false; everything else is converted to true.
+void test1() {
+ bool b1 = 0.99f; // expected-warning {{implicit conversion from 'float' to 'bool' changes value from 0.99 to true}}
+ bool b2 = 0.99; // expected-warning {{implicit conversion from 'double' to 'bool' changes value from 0.99 to true}}
+ // These do not warn because they can be directly converted to integral
+ // values.
+ bool b3 = 0.0f;
+ bool b4 = 0.0;
+}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -6983,7 +6983,7 @@
SmallString<16> PrettyTargetValue;
if (T->isSpecificBuiltinType(BuiltinType::Bool))
- PrettyTargetValue = IntegerValue == 0 ? "false" : "true";
+ PrettyTargetValue = Value.isZero() ? "false" : "true";
else
IntegerValue.toString(PrettyTargetValue);
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