Warn when a fraction is stored into a variable inferred from an integer literal

[ASDAlexander77]

Problem

Integer literals are s32 in tslang, so let s = 0 is an integer and a fraction stored into it is dropped silently:

let s = 0;
s += 1.5;
print(s);              // 1 (TypeScript: 1.5)

function sum(values: number[]): number {
    let a = 0;
    for (...) a += values[i];
    return a;          // sum([1.5, 0, 2]) gives 3, not 3.5
}

Reported in docs/bugs/native-ts-graphics-findings.md, issue 3. Inferring s32 from integer literals is deliberate, and this PR keeps it. The report asks for what this PR adds: a warning when ordinary TypeScript code changes meaning because of it.

Change

When a store into a variable converts a value of type number (or another float type) to the variable's integer type, and that type was inferred from an integer literal, it warns:

global.ts:3:1: warning: a 'number' is stored in a 's32', so any fraction is dropped: the variable's type was
inferred from an integer literal. Declare it 'number' (e.g. `let s: number = 0`) to keep fractions

No warning for:

• a whole-number constant (s = 3.0);
• a variable whose integer type was declared (let d: s32 = 0; d = 2.5), since that truncation was asked for;
• a variable inferred from 0.0, or declared number.

How it works: adjustLocalVariableType/adjustGlobalVariableType note that the type was inferred from an integer literal (no type given, and the initializer has a literal integer type). registerVariable marks the storage (ts.Variable, or ts.Global for a global) with INTEGER_LITERAL_INFERRED_ATTR_NAME, and mlirGenSaveLogicOneItem checks that mark before it casts the stored value. This covers =, += and the other compound assignments. Code generation doesn't change.

Stores from inside a closure (a.forEach(v => { s += v; })) are warned about too.

Testing

• New warning-text tests: test-compile-integer-literal-truncation-global and -local require the warning at the store's line and column; -quiet fails on any warning, for the cases listed above. The current release prints no warning, so -global and -local fail on it.
• Full ctest: 3916/3916 pass.
• Noise check: compiled every file in tslang/test/tester/tests (about 630). 27 of them warn, in 1 to 5 places each. All are real number-to-s32 stores into a let x = 0 variable, such as x /= 5, total = total + n.v, glb1 += x and dist = v - Math.sqrt(disc). The compiler can't know whether those values have a fraction at run time, which is why the message says "any fraction". If that's too noisy for code that relies on the integer inference on purpose, the fix is to declare the type (let x: s32 = 0), which turns the warning off.

🤖 Generated with Claude Code