Improve test coverage of -Wdouble-promotion

[rob.lougher]

Summary

The -Wdouble-promotion warning was added to clang in r251588 (fixing PR15109). The added test, however, only covered a subset of the cases where implicit conversion can occur (assignment and function return). This patch extends the coverage to include argument passing and a binary operator (multiply).

The patch also includes coverage for *= and the conditional (ternary) operator. However, warnings are not produced for all the *= cases, and no warnings are generated for the conditional operator. These have been marked as FIXME and I will raise bugs for these separately.

Note, I've added George Burgess IV as reviewer as he committed the original change and Carl Norum (the author) doesn't seem to be registered.

[rob.lougher]

Ping.

[rob.lougher]

Ping. Just test changes - OK to commit?

[rob.lougher]

Ping. Please can somebody review this? Thanks!

[rob.lougher]

Ping.

[george.burgess.iv]

Hey -- I'm really sorry about the latency on this; I recently (within the last month) discovered that I don't actually receive an email for reviews sent to gbiv, so I had to make a filter specifically to catch things like this. As a result, this is the first time I'm seeing that I'm a reviewer for this. :(

Sorry again, and LGTM.

[rob.lougher]

No problem. Thanks for the code review.

cfe/trunk/test/Sema/warn-double-promotion.c

 long double ReturnLongDoubleFromFloat(float f) {
   return f;  //expected-warning{{implicit conversion increases floating-point precision: 'float' to 'long double'}}
 }
 
 long double ReturnLongDoubleFromDouble(double d) {
   return d;  //expected-warning{{implicit conversion increases floating-point precision: 'double' to 'long double'}}
 }
 
-void Convert(float f, double d, long double ld) {
+void Assignment(float f, double d, long double ld) {
   d = f;  //expected-warning{{implicit conversion increases floating-point precision: 'float' to 'double'}}
   ld = f; //expected-warning{{implicit conversion increases floating-point precision: 'float' to 'long double'}}
   ld = d; //expected-warning{{implicit conversion increases floating-point precision: 'double' to 'long double'}}
   f = d;
   f = ld;
   d = ld;
 }
+
+extern void DoubleParameter(double);
+extern void LongDoubleParameter(long double);
+
+void ArgumentPassing(float f, double d) {
+  DoubleParameter(f); // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'double'}}
+  LongDoubleParameter(f); // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'long double'}}
+  LongDoubleParameter(d); // expected-warning{{implicit conversion increases floating-point precision: 'double' to 'long double'}}
+}
+
+void BinaryOperator(float f, double d, long double ld) {
+  f = f * d; // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'double'}}
+  f = d * f; // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'double'}}
+  f = f * ld; // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'long double'}}
+  f = ld * f; // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'long double'}}
+  d = d * ld; // expected-warning{{implicit conversion increases floating-point precision: 'double' to 'long double'}}
+  d = ld * d; // expected-warning{{implicit conversion increases floating-point precision: 'double' to 'long double'}}
+}
+
+void MultiplicationAssignment(float f, double d, long double ld) {
+  d *= f; // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'double'}}
+  ld *= f; // expected-warning{{implicit conversion increases floating-point precision: 'float' to 'long double'}}
+  ld *= d; // expected-warning{{implicit conversion increases floating-point precision: 'double' to 'long double'}}
+
+  // FIXME: These cases should produce warnings as above.
+  f *= d;
+  f *= ld;
+  d *= ld;
+}
+
+// FIXME: As with a binary operator, the operands to the conditional operator are
+// converted to a common type and should produce a warning.
+void ConditionalOperator(float f, double d, long double ld, int i) {
+  f = i ? f : d;
+  f = i ? d : f;
+  f = i ? f : ld;
+  f = i ? ld : f;
+  d = i ? d : ld;
+  d = i ? ld : d;
+}