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Module dmd.escape

Most of the logic to implement scoped pointers and scoped references is here.

Documentation

https://dlang.org/phobos/dmd_escape.html

Coverage

https://codecov.io/gh/dlang/dmd/src/master/src/dmd/escape.d

Functions

NameDescription
checkArrayLiteralEscape(sc, ae, gag) Array literal is going to be allocated on the GC heap. Check its elements to see if any would escape by going on the heap.
checkAssignEscape(sc, e, gag, byRef) Given an AssignExp, determine if the lvalue will cause the contents of the rvalue to escape. Print error messages when these are detected. Infer scope attribute for the lvalue where possible, in order to eliminate the error.
checkAssocArrayLiteralEscape(sc, ae, gag) Associative array literal is going to be allocated on the GC heap. Check its elements to see if any would escape by going on the heap.
checkConstructorEscape(sc, ce, gag) Check struct constructor of the form s.this(args), by checking each return parameter to see if it gets assigned to s.
checkMutableArguments(sc, fd, tf, ethis, arguments, gag) Checks memory objects passed to a function. Checks that if a memory object is passed by ref or by pointer, all of the refs or pointers are const, or there is only one mutable ref or pointer to it.
checkNewEscape(sc, e, gag) Detect cases where pointers to the stack can escape the lifetime of the stack frame by being placed into a GC allocated object. Print error messages when these are detected.
checkParamArgumentEscape(sc, fdc, parId, vPar, parStc, arg, assertmsg, gag) Function parameter par is being initialized to arg, and par may escape. Detect if scoped values can escape this way. Print error messages when these are detected.
checkParamArgumentReturn(sc, firstArg, arg, param, gag) Function argument initializes a return parameter, and that parameter gets assigned to firstArg. Essentially, treat as firstArg = arg;
checkReturnEscape(sc, e, gag) Detect cases where pointers to the stack can escape the lifetime of the stack frame by returning e by value. Print error messages when these are detected.
checkReturnEscapeRef(sc, e, gag) Detect cases where returning e by ref can result in a reference to the stack being returned. Print error messages when these are detected.
checkThrowEscape(sc, e, gag) Detect cases where pointers to the stack can escape the lifetime of the stack frame when throwing e. Print error messages when these are detected.
escapeByRef(e, er, live, retRefTransition) e is an expression to be returned by 'ref'. Walk e to determine which variables are possibly being returned by ref, such as: ref int function(int i) { return i; } If e is a form of *p, determine which variables have content which is being returned as ref, such as: ref int function(int* p) { return *p; } Multiple variables can be inserted, because of expressions like this: ref int function(bool b, int i, int* p) { return b ? i : *p; }
escapeByValue(e, er, live, retRefTransition) e is an expression to be returned by value, and that value contains pointers. Walk e to determine which variables are possibly being returned by value, such as: int* function(int* p) { return p; } If e is a form of &p, determine which variables have content which is being returned as ref, such as: int* function(int i) { return &i; } Multiple variables can be inserted, because of expressions like this: int function(bool b, int i, int* p) { return b ? &i : p; }
findAllOuterAccessedVariables(fd, vars) Find all variables accessed by this delegate that are in functions enclosing it.
finishScopeParamInference(funcdecl, f) After semantic analysis of the function body, try to infer scope / return on the parameters
inferScope(va) Infer scope for a variable
isReferenceToMutable(t) Is type a reference to a mutable value?
isReferenceToMutable(p, t) Is parameter a reference to a mutable value?
printScopeFailure(printFunc, v, recursionLimit) A scope variable was assigned to non-scope parameter v. If applicable, print why the parameter was not inferred scope.

Structs

NameDescription
EscapeByResults Aggregate the data collected by the escapeBy??() functions.

Authors

Walter Bright

License

Boost License 1.0