Do not round `a**b` to infinity

... instead, just calculate the value unless it is too big.
Also, this change raises an ArgumentError if it is expected to exceed
16 GB in a 64-bit environment.

(It is possible to calculate it straightforward, but it would likely be
out-of-memory, so I didn't think it would make sense.)

[Feature #20811]

2 files changed, 102 insertions, 40 deletions

diff --git a/spec/ruby/core/integer/shared/exponent.rb b/spec/ruby/core/integer/shared/exponent.rb
index 15df518b7e..5ef6d686d8 100644
--- a/spec/ruby/core/integer/shared/exponent.rb
+++ b/spec/ruby/core/integer/shared/exponent.rb
@@ -48,10 +48,18 @@ describe :integer_exponent, shared: true do
       (-1).send(@method, 4611686018427387905).should eql(-1)
     end
 
-    it "returns Float::INFINITY when the number is too big" do
-      -> {
-        2.send(@method, 427387904).should == Float::INFINITY
-      }.should complain(/warning: in a\*\*b, b may be too big/)
+    ruby_version_is ""..."3.4" do
+      it "returns Float::INFINITY when the number is too big" do
+        -> {
+          2.send(@method, 427387904).should == Float::INFINITY
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "raises an ArgumentError when the number is too big" do
+        -> { 100000000.send(@method, 1000000000) }.should raise_error(ArgumentError)
+      end
     end
 
     it "raises a ZeroDivisionError for 0 ** -1" do
@@ -108,13 +116,23 @@ describe :integer_exponent, shared: true do
       -> { @bignum.send(@method, :symbol) }.should raise_error(TypeError)
     end
 
-    it "switch to a Float when the values is too big" do
-      flt = nil
-      -> {
-        flt = @bignum.send(@method, @bignum)
-      }.should complain(/warning: in a\*\*b, b may be too big/)
-      flt.should be_kind_of(Float)
-      flt.infinite?.should == 1
+    ruby_version_is ""..."3.4" do
+      it "switch to a Float when the values is too big" do
+        flt = nil
+        -> {
+          flt = @bignum.send(@method, @bignum)
+        }.should complain(/warning: in a\*\*b, b may be too big/)
+        flt.should be_kind_of(Float)
+        flt.infinite?.should == 1
+      end
+    end
+
+    ruby_version_is "3.4" do
+      it "does not switch to a Float when the values is too big" do
+        -> {
+          @bignum.send(@method, @bignum)
+        }.should raise_error(ArgumentError)
+      end
     end
 
     it "returns a complex number when negative and raised to a fractional power" do
diff --git a/spec/ruby/shared/rational/exponent.rb b/spec/ruby/shared/rational/exponent.rb
index b0e9b23574..2145d6bace 100644
--- a/spec/ruby/shared/rational/exponent.rb
+++ b/spec/ruby/shared/rational/exponent.rb
@@ -84,47 +84,91 @@ describe :rational_exponent, shared: true do
       (Rational(-1) ** bignum_value(3)).should eql(Rational(-1))
     end
 
-    it "returns positive Infinity when self is > 1" do
-      -> {
-        (Rational(2) ** bignum_value).infinite?.should == 1
-      }.should complain(/warning: in a\*\*b, b may be too big/)
-      -> {
-        (Rational(fixnum_max) ** bignum_value).infinite?.should == 1
-      }.should complain(/warning: in a\*\*b, b may be too big/)
-    end
-
-    it "returns 0.0 when self is > 1 and the exponent is negative" do
-      -> {
-        (Rational(2) ** -bignum_value).should eql(0.0)
-      }.should complain(/warning: in a\*\*b, b may be too big/)
-      -> {
-        (Rational(fixnum_max) ** -bignum_value).should eql(0.0)
-      }.should complain(/warning: in a\*\*b, b may be too big/)
-    end
-
-    # Fails on linux due to pow() bugs in glibc: http://sources.redhat.com/bugzilla/show_bug.cgi?id=3866
-    platform_is_not :linux do
-      it "returns positive Infinity when self < -1" do
+    ruby_version_is ""..."3.4" do
+      it "returns positive Infinity when self is > 1" do
         -> {
-          (Rational(-2) ** bignum_value).infinite?.should == 1
+          (Rational(2) ** bignum_value).infinite?.should == 1
         }.should complain(/warning: in a\*\*b, b may be too big/)
         -> {
-          (Rational(-2) ** (bignum_value + 1)).infinite?.should == 1
-        }.should complain(/warning: in a\*\*b, b may be too big/)
-        -> {
-          (Rational(fixnum_min) ** bignum_value).infinite?.should == 1
+          (Rational(fixnum_max) ** bignum_value).infinite?.should == 1
         }.should complain(/warning: in a\*\*b, b may be too big/)
       end
 
-      it "returns 0.0 when self is < -1 and the exponent is negative" do
+      it "returns 0.0 when self is > 1 and the exponent is negative" do
         -> {
-          (Rational(-2) ** -bignum_value).should eql(0.0)
+          (Rational(2) ** -bignum_value).should eql(0.0)
         }.should complain(/warning: in a\*\*b, b may be too big/)
         -> {
-          (Rational(fixnum_min) ** -bignum_value).should eql(0.0)
+          (Rational(fixnum_max) ** -bignum_value).should eql(0.0)
         }.should complain(/warning: in a\*\*b, b may be too big/)
       end
     end
+
+    ruby_version_is "3.4" do
+      it "raises an ArgumentError when self is > 1" do
+        -> {
+          (Rational(2) ** bignum_value)
+        }.should raise_error(ArgumentError)
+        -> {
+          (Rational(fixnum_max) ** bignum_value)
+        }.should raise_error(ArgumentError)
+      end
+
+      it "raises an ArgumentError when self is > 1 and the exponent is negative" do
+        -> {
+          (Rational(2) ** -bignum_value)
+        }.should raise_error(ArgumentError)
+        -> {
+          (Rational(fixnum_max) ** -bignum_value)
+        }.should raise_error(ArgumentError)
+      end
+    end
+
+    # Fails on linux due to pow() bugs in glibc: http://sources.redhat.com/bugzilla/show_bug.cgi?id=3866
+    platform_is_not :linux do
+      ruby_version_is ""..."3.4" do
+        it "returns positive Infinity when self < -1" do
+          -> {
+            (Rational(-2) ** bignum_value).infinite?.should == 1
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+          -> {
+            (Rational(-2) ** (bignum_value + 1)).infinite?.should == 1
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+          -> {
+            (Rational(fixnum_min) ** bignum_value).infinite?.should == 1
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+        end
+
+        it "returns 0.0 when self is < -1 and the exponent is negative" do
+          -> {
+            (Rational(-2) ** -bignum_value).should eql(0.0)
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+          -> {
+            (Rational(fixnum_min) ** -bignum_value).should eql(0.0)
+          }.should complain(/warning: in a\*\*b, b may be too big/)
+        end
+      end
+
+      ruby_version_is "3.4" do
+        it "returns positive Infinity when self < -1" do
+          -> {
+            (Rational(-2) ** bignum_value)
+          }.should raise_error(ArgumentError)
+          -> {
+            (Rational(fixnum_min) ** bignum_value)
+          }.should raise_error(ArgumentError)
+        end
+
+        it "returns 0.0 when self is < -1 and the exponent is negative" do
+          -> {
+            (Rational(-2) ** -bignum_value)
+          }.should raise_error(ArgumentError)
+          -> {
+            (Rational(fixnum_min) ** -bignum_value)
+          }.should raise_error(ArgumentError)
+        end
+      end
+    end
   end
 
   describe "when passed Float" do