mruby · matz · Aug 17, 2026 · Aug 17, 2026 · Aug 17, 2026 · coderabbitai
@@ -85,6 +85,7 @@ end
 
 - When defined removes floating-point numbers from mruby.
 - It makes mruby easier to handle in "Micro-controller without FPU" and "Kernel Space".
+- A floating-point literal in Ruby source is read as the Integer `0`, with a compiler warning.
 
 `MRB_INT32`
 

@@ -30,6 +30,22 @@
   assert_equal 1, $?.exitstatus
 end
 
+assert('a float literal under MRB_NO_FLOAT is read as 0 with a warning') do
+  # Only a build without Float takes this path.  Whether this is one is asked
+  # of its mruby, when there is one; mrbc itself cannot be asked.
+  skip 'no mruby to probe the build with' unless File.exist?(cmd_bin('mruby'))
+  system("#{cmd('mruby')} -e Float", out: File::NULL, err: File::NULL)
+  skip 'this build has Float' if $?.success?
+
+  a, out = Tempfile.new('a.rb'), Tempfile.new('out.mrb')
+  a.write("x = 1\np 1.5\n")
+  a.flush
+  result = `#{cmd('mrbc')} -v -o #{out.path} #{a.path} 2>&1`
+  assert_equal 0, $?.exitstatus
+  assert_include result, "#{a.path}:2:3: generator warning, floating-point numbers are not supported"
+  assert_equal "0\n", `#{cmd('mruby')} -b #{out.path}`
+end
+
 assert('mrbc -v disassembles like mruby -v') do
   # mruby-compiler carries its own copy of the disassembler, because it has to
   # build for mruby/c as well and cannot share src/codedump.c. The copy has

@@ -4690,18 +4690,29 @@ codegen(mrc_codegen_scope *s, mrc_node *tree, int val)
       }
       break;
     }
-#ifndef MRC_NO_FLOAT
   case PM_FLOAT_NODE:
   {
+#ifndef MRC_NO_FLOAT
     if (val) {
       CAST(float);
       int off = new_lit_float(s, (mrc_float)cast->value);
       genop_2(s, OP_LOADL, cursp(), off);
       push();
     }
+#else
+    /* A build without Float still has to compile source that spells a
+       float literal, so the literal is warned about and read as Integer 0,
+       as the lrama parser did under MRB_NO_FLOAT. */
+    mrc_diagnostic_list_append(s->c, tree->location.start,
+                               "floating-point numbers are not supported",
+                               MRC_GENERATOR_WARNING);
+    if (val) {
+      gen_int(s, cursp(), 0);
+      push();
+    }
+#endif
     break;
   }
-#endif
     case PM_CALL_NODE:
     {
       CAST(call);

@@ -647,7 +647,7 @@ class StringMatchHelperOverride < String
   assert_equal ["a", ""], "a,".split(/,/, 2)
   assert_equal ["a,b,"], "a,b,".split(/,/, 1)
   assert_raise(TypeError) { "a,b".split(/,/, nil) }
-  assert_equal ["a,b"], "a,b".split(/,/, 1.5)
+  assert_equal ["a,b"], "a,b".split(/,/, 1.5) if Object.const_defined?(:Float)
 
   # mruby has no implicit conversion protocol, so an object defining `to_int`
   # is rejected here exactly as `Array.new(obj)` and `ary[obj]` reject it. The

@@ -15,13 +15,13 @@
   # CRuby raises ArgumentError for offsets too large to represent.
   # mruby has no Bignum bit offsets and raises RangeError instead:
   # without mruby-bigint the power itself overflows, with it the
-  # offset conversion rejects the Bigint.  Either way this compiles
-  # in every build configuration (a float literal like 1e30 would
-  # not compile under MRB_NO_FLOAT).
+  # offset conversion rejects the Bigint.  Either way this raises
+  # in every build configuration (a float literal like 1e30 reads
+  # as 0 under MRB_NO_FLOAT).
   assert_raise(RangeError) { s.bit_get(2 ** 100) }
 
   # The Float path of the offset conversion, built without a float
-  # literal so MRB_NO_FLOAT builds can still compile this file.
+  # literal, which MRB_NO_FLOAT builds would read as 0.
   if 1.respond_to?(:to_f)
     huge = (1 << 30).to_f
     huge = huge * huge * 16  # 2.0**64, beyond mrb_int in any build

@@ -349,6 +349,7 @@ def with_builtin_string_aref
 # retain nothing and the assertions hold trivially.
 
 assert('OP_MATH does not retain a boxed Float in the GC arena') do
+  skip unless Object.const_defined?(:Float)
   [1.0e100, 5.0e-324].each do |x|
     zero = 0.0
     one = 1.0
@@ -369,6 +370,7 @@ def with_builtin_string_aref
 end
 
 assert('OP_DIV does not retain a boxed Float in the GC arena') do
+  skip unless Object.const_defined?(:Float)
   # OP_DIV boxes from a helper outside the interpreter loop, so it restores to
   # its own saved arena index rather than to the frame's.
   [1.0e100, 5.0e-324].each do |x|
@@ -388,6 +390,7 @@ def with_builtin_string_aref
 end
 
 assert('OP_ADDI does not retain a boxed Float in the GC arena') do
+  skip unless Object.const_defined?(:Float)
   x = 1.0e100
   y = nil
   GC.start
@@ -407,6 +410,7 @@ def with_builtin_string_aref
 end
 
 assert('OP_LOADL does not retain a boxed Float in the GC arena') do
+  skip unless Object.const_defined?(:Float)
   y = nil
   GC.start
   base = GC.stat[:live]

@@ -343,7 +343,7 @@
   assert_raise(TypeError) { Integer.__ensure(Class.new { def to_int; 2; end }.new) }
 
   assert_equal 2, Integer.__ensure(2)
-  assert_equal 1, Integer.__ensure(1.9)
+  assert_equal 1, Integer.__ensure(1.9) if Object.const_defined?(:Float)
   assert_raise(TypeError) { Integer.__ensure("2") }
   assert_raise(TypeError) { Integer.__ensure(nil) }
 end
@@ -35,6 +35,17 @@
   assert_equal 10.0, 1.0e+1
 end
 
+assert('Literals Numerical without Float') do
+  # A build without Float (MRB_NO_FLOAT) reads a float literal as the Integer
+  # 0, with a compiler warning, so a shared test file still compiles and its
+  # Float rows can be skipped at run time.
+  skip 'Float is defined' if Object.const_defined?(:Float)
+  assert_equal 0, 1.5
+  assert_equal 0, -1.5
+  assert_equal 0, 1e10
+  assert_equal Integer, 1.5.class
+end
+
 assert('Literals Numerical wider than mrb_int') do
   # None of these fit mrb_int on MRB_INT32, so the compiler has to hand them
   # to the VM as big integer literals.  A shift is written on the other side

@@ -1629,7 +1629,7 @@ class DefinedPathChild < DefinedPathBase; end
   assert_equal 'constant', defined?(DefinedPathChild::Sub)
 
   # a builtin nested constant
-  assert_equal 'constant', defined?(Float::INFINITY)
+  assert_equal 'constant', defined?(Float::INFINITY) if Object.const_defined?(:Float)
 end
 
 # NOTE: `&nil` block-forbidding parameters live in syntax_block_forbid.rb,