[Bug c++/8861] [3.3/3.4 regression] [ABI] mangling floating point literal in template arg expression

[rearnsha@arm.com]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8861



------- Additional Comments From rearnsha@arm.com  2003-06-10 11:09 -------
Subject: Re:  Revised patch - floating point literal mangling 

+    Here are some examples, assuming the IEEE standard representation
+    for floating point numbers.  (Spaces are for readability, not
+    part of the encoding.)
+
+        1.0f                    Lf 3f80 0000 E
+       -1.0f                    Lf bf80 0000 E
+        1.17549435e-38f         Lf 0080 0000 E
+        1.40129846e-45f         Lf 0000 0001 E
+        0.0f                    Lf 0000 0000 E"
+

What about issues related to accuracy of translation (rounding style, 
excess precision etc).  There are many floating point numbers where it is 
hard if not impossible to guarantee that two independent implementations 
will produce the same result.  That effectively means that the ABI is 
mandating something which is ambiguously specified.

I'm surprised, given that 

	template <int I> void f(A<I+int(1.234+1.234)> a) { ... }

and

	template <int I> void f(A<I+int(2.468)> a) { ... }

don't mangle identically, that a representation of the literal *as it 
appeared in the source* isn't used.

R.