Take a floating-point remainder with fmod or math.Mod in C, C++ and Go [patch]

[matt-edmondson]

Fixes #174

What changed

C, C++ and Go define % on integers only. A remainder or %= of double or float operands was written as % anyway, and none of the three compiled it.

• StandardLanguageGenerator gains FloatingRemainderType, which returns the floating type of a remainder when either operand's static type is float or double. It also gains a SpellsFloatingRemainderAsCall / WriteFloatingRemainder hook.

• GenerateBinary lowers a floating Modulo through that hook. A new GenerateAssignmentStatement override lowers a floating x %= y to x = <call>(x, y). Go's own override still defers to it for any value that is not a conditional.

• What each target writes:

  Target	double	float	Import
  C	fmod(a, b)	fmodf(a, b)	<math.h>
  C++	std::fmod(a, b)	std::fmod(a, b)	<cmath>
  Go	math.Mod(a, b)	float32(math.Mod(float64(a), float64(b)))	"math"

• Before this change, C and C++ never pushed a static-type scope. GenerateFunction now opens one and GenerateVariableDeclaration registers each local, the same way Go already did. That is the prerequisite the triage comment shares with Calling a method through a pointer or reference, or on another call's result, generates C, C++ and Rust that doesn't compile #170.

• Imports are written before the body, so ContainsFloatingRemainder(SourceFile) asks the question of the AST. It puts each function's parameters and locals in scope and then looks for a floating % or %=. Go needs this to be exact, because an unused "math" import does not compile there.

• Integer % and %= are unchanged, and C#, Rust, Python and JavaScript are untouched, since the hook defaults to off.

Tests (FloatingRemainderTests)

• AFloatingRemainderIsACall (C, C++, Go): checks the spelling of double % double, float % float and %= on a double local.
• AnIntegerRemainderIsUnchanged (C, C++, Go): int % and %= are still written as %.
• OnlyAFloatingRemainderImportsItsCall (C, C++, Go): the header or package appears exactly once for floating remainders, and not at all for integer ones.
• RemaindersCompile (C, C++, Go): both files compile with gcc -std=c11 -Wall -Wextra -pedantic -Werror, g++ -std=c++20 … -Werror and go vet.

With the generator changes reverted, 9 of the 12 fail. The 3 that still pass are the unchanged integer rows. With the changes, the full suite passes (1127/1127).

🤖 Generated with Claude Code

https://claude.ai/code/session_01NgDciLntSfQTDeqFaJ3BM1

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
97.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud