Allow 'Infinity' and '-Infinity' as input to the float4 and float8

types. Update the regression tests and the documentation to reflect
this. Remove the UNSAFE_FLOATS #ifdef.

This is only half the story: we still unconditionally reject
floating point operations that result in +/- infinity. See
recent thread on -hackers for more information.

src/test/regress/expected/float4.out

@@ -50,9 +50,39 @@ SELECT '   NAN  '::float4;
     NaN
 (1 row)
 
+SELECT 'infinity'::float4;
+  float4  
+----------
+ Infinity
+(1 row)
+
+SELECT '          -INFINiTY   '::float4;
+  float4   
+-----------
+ -Infinity
+(1 row)
+
 -- bad special inputs
 SELECT 'N A N'::float4;
 ERROR:  invalid input syntax for type real: "N A N"
+SELECT 'NaN x'::float4;
+ERROR:  invalid input syntax for type real: "NaN x"
+SELECT ' INFINITY    x'::float4;
+ERROR:  invalid input syntax for type real: " INFINITY    x"
+SELECT 'Infinity'::float4 + 100.0;
+ERROR:  type "double precision" value out of range: overflow
+SELECT 'Infinity'::float4 / 'Infinity'::float4;
+ ?column? 
+----------
+      NaN
+(1 row)
+
+SELECT 'nan'::float4 / 'nan'::float4;
+ ?column? 
+----------
+      NaN
+(1 row)
+
 SELECT '' AS five, FLOAT4_TBL.*;
  five |     f1      
 ------+-------------

src/test/regress/expected/float8.out

@@ -50,9 +50,39 @@ SELECT '   NAN  '::float8;
     NaN
 (1 row)
 
+SELECT 'infinity'::float8;
+  float8  
+----------
+ Infinity
+(1 row)
+
+SELECT '          -INFINiTY   '::float8;
+  float8   
+-----------
+ -Infinity
+(1 row)
+
 -- bad special inputs
 SELECT 'N A N'::float8;
 ERROR:  invalid input syntax for type double precision: "N A N"
+SELECT 'NaN x'::float8;
+ERROR:  invalid input syntax for type double precision: "NaN x"
+SELECT ' INFINITY    x'::float8;
+ERROR:  invalid input syntax for type double precision: " INFINITY    x"
+SELECT 'Infinity'::float8 + 100.0;
+ERROR:  type "double precision" value out of range: overflow
+SELECT 'Infinity'::float8 / 'Infinity'::float8;
+ ?column? 
+----------
+      NaN
+(1 row)
+
+SELECT 'nan'::float8 / 'nan'::float8;
+ ?column? 
+----------
+      NaN
+(1 row)
+
 SELECT '' AS five, FLOAT8_TBL.*;
  five |          f1          
 ------+----------------------

src/test/regress/sql/float4.sql

@@ -29,8 +29,17 @@ INSERT INTO FLOAT4_TBL(f1) VALUES ('123            5');
 SELECT 'NaN'::float4;
 SELECT 'nan'::float4;
 SELECT '   NAN  '::float4;
+SELECT 'infinity'::float4;
+SELECT '          -INFINiTY   '::float4;
 -- bad special inputs
 SELECT 'N A N'::float4;
+SELECT 'NaN x'::float4;
+SELECT ' INFINITY    x'::float4;
+
+SELECT 'Infinity'::float4 + 100.0;
+SELECT 'Infinity'::float4 / 'Infinity'::float4;
+SELECT 'nan'::float4 / 'nan'::float4;
+
 
 SELECT '' AS five, FLOAT4_TBL.*;
 

src/test/regress/sql/float8.sql

@@ -29,8 +29,16 @@ INSERT INTO FLOAT8_TBL(f1) VALUES ('123           5');
 SELECT 'NaN'::float8;
 SELECT 'nan'::float8;
 SELECT '   NAN  '::float8;
+SELECT 'infinity'::float8;
+SELECT '          -INFINiTY   '::float8;
 -- bad special inputs
 SELECT 'N A N'::float8;
+SELECT 'NaN x'::float8;
+SELECT ' INFINITY    x'::float8;
+
+SELECT 'Infinity'::float8 + 100.0;
+SELECT 'Infinity'::float8 / 'Infinity'::float8;
+SELECT 'nan'::float8 / 'nan'::float8;
 
 SELECT '' AS five, FLOAT8_TBL.*;