Add -Wabsolute-value, warnings about absolute value functions.
The warnings fall into three groups.
1) Using an absolute value function of the wrong type, for instance, using the
int absolute value function when the argument is a floating point type.
2) Using the improper sized absolute value function, for instance, using abs
when the argument is a long long. llabs should be used instead.
From these two cases, an implicit conversion will occur which may cause
unexpected behavior. Where possible, suggest the proper absolute value
function to use, and which header to include if the function is not available.
3) Taking the absolute value of an unsigned value. In addition to this warning,
suggest to remove the function call. This usually indicates a logic error
since the programmer assumed negative values would have been possible.
llvm-svn: 202211
diff --git a/clang/test/SemaCXX/warn-absolute-value-header.cpp b/clang/test/SemaCXX/warn-absolute-value-header.cpp
new file mode 100644
index 0000000..01aaabc
--- /dev/null
+++ b/clang/test/SemaCXX/warn-absolute-value-header.cpp
@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -fsyntax-only -verify %s -Wabsolute-value
+// RUN: %clang_cc1 -triple i686-pc-linux-gnu -fsyntax-only %s -Wabsolute-value -fdiagnostics-parseable-fixits 2>&1 | FileCheck %s
+
+extern "C" int abs(int);
+
+// Wrong signature
+int fabsf(int);
+
+void test_int(int i, unsigned u, long long ll, float f, double d) {
+ (void)abs(i);
+
+ // Remove abs call
+ (void)abs(u);
+ // expected-warning@-1{{taking the absolute value of unsigned type 'unsigned int' has no effect}}
+ // expected-note@-2{{remove the call to 'abs' since unsigned values cannot be negative}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:9-[[@LINE-3]]:12}:""
+
+ int llabs;
+ (void)llabs;
+ // Conflict in names, suggest qualified name
+ (void)abs(ll);
+ // expected-warning@-1{{absolute value function 'abs' given an argument of type 'long long' but has parameter of type 'int' which may cause truncation of value}}
+ // expected-note@-2{{use function '::llabs' instead}}
+ // expected-note@-3{{please include the header <stdlib.h> or explicitly provide a declaration for 'llabs'}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:9-[[@LINE-4]]:12}:"::llabs"
+
+ // Conflict in names, no notes
+ (void)abs(f);
+ // expected-warning@-1{{using integer absolute value function 'abs' when argument is of floating point type}}
+
+ // Suggest header.
+ (void)abs(d);
+ // expected-warning@-1{{using integer absolute value function 'abs' when argument is of floating point type}}
+ // expected-note@-2{{use function 'fabs' instead}}
+ // expected-note@-3{{please include the header <math.h> or explicitly provide a declaration for 'fabs'}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:9-[[@LINE-4]]:12}:"fabs"
+}