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| 1 | +private import rust |
| 2 | +private import codeql.rust.elements.internal.generated.ParentChild |
| 3 | +private import codeql.rust.elements.internal.PathExprImpl::Impl as PathExprImpl |
| 4 | + |
| 5 | +module Impl { |
| 6 | + /** |
| 7 | + * A variable scope. Either a block `{ ... }`, the guard/rhs |
| 8 | + * of a match arm, or the body of a closure. |
| 9 | + */ |
| 10 | + abstract class VariableScope extends AstNode { } |
| 11 | + |
| 12 | + class BlockExprScope extends VariableScope, BlockExpr { } |
| 13 | + |
| 14 | + abstract class MatchArmScope extends VariableScope { |
| 15 | + MatchArm arm; |
| 16 | + |
| 17 | + bindingset[arm] |
| 18 | + MatchArmScope() { exists(arm) } |
| 19 | + |
| 20 | + Pat getPat() { result = arm.getPat() } |
| 21 | + } |
| 22 | + |
| 23 | + class MatchArmExprScope extends MatchArmScope { |
| 24 | + MatchArmExprScope() { this = arm.getExpr() } |
| 25 | + } |
| 26 | + |
| 27 | + class MatchArmGuardScope extends MatchArmScope { |
| 28 | + MatchArmGuardScope() { this = arm.getGuard() } |
| 29 | + } |
| 30 | + |
| 31 | + class ClosureBodyScope extends VariableScope { |
| 32 | + ClosureBodyScope() { this = any(ClosureExpr ce).getBody() } |
| 33 | + } |
| 34 | + |
| 35 | + private Pat getImmediatePatParent(AstNode n) { |
| 36 | + result = getImmediateParent(n) |
| 37 | + or |
| 38 | + result.(RecordPat).getRecordPatFieldList().getAField().getPat() = n |
| 39 | + } |
| 40 | + |
| 41 | + private Pat getAPatAncestor(Pat p) { |
| 42 | + (p instanceof IdentPat or p instanceof OrPat) and |
| 43 | + exists(Pat p0 | result = getImmediatePatParent(p0) | |
| 44 | + p0 = p |
| 45 | + or |
| 46 | + p0 = getAPatAncestor(p) and |
| 47 | + not p0 instanceof OrPat |
| 48 | + ) |
| 49 | + } |
| 50 | + |
| 51 | + /** Gets the immediately enclosing `|` pattern of `p`, if any */ |
| 52 | + private OrPat getEnclosingOrPat(Pat p) { result = getAPatAncestor(p) } |
| 53 | + |
| 54 | + /** Gets the outermost enclosing `|` pattern parent of `p`, if any. */ |
| 55 | + private OrPat getOutermostEnclosingOrPat(IdentPat p) { |
| 56 | + result = getEnclosingOrPat+(p) and |
| 57 | + not exists(getEnclosingOrPat(result)) |
| 58 | + } |
| 59 | + |
| 60 | + /** |
| 61 | + * Holds if `p` declares a variable named `name` at `definingNode`. Normally, |
| 62 | + * `definingNode = p`, except in cases like |
| 63 | + * |
| 64 | + * ```rust |
| 65 | + * match either { |
| 66 | + * Either::Left(x) | Either::Right(x) => println!(x), |
| 67 | + * } |
| 68 | + * ``` |
| 69 | + * |
| 70 | + * where `definingNode` is the entire `Either::Left(x) | Either::Right(x)` |
| 71 | + * pattern. |
| 72 | + */ |
| 73 | + private predicate variableDecl(AstNode definingNode, IdentPat p, string name) { |
| 74 | + ( |
| 75 | + definingNode = getOutermostEnclosingOrPat(p) |
| 76 | + or |
| 77 | + not exists(getOutermostEnclosingOrPat(p)) and |
| 78 | + definingNode = p.getName() |
| 79 | + ) and |
| 80 | + name = p.getName().getText() |
| 81 | + } |
| 82 | + |
| 83 | + /** A variable. */ |
| 84 | + class Variable extends MkVariable { |
| 85 | + private AstNode definingNode; |
| 86 | + private string name; |
| 87 | + |
| 88 | + Variable() { this = MkVariable(definingNode, name) } |
| 89 | + |
| 90 | + /** Gets the name of this variable. */ |
| 91 | + string getName() { result = name } |
| 92 | + |
| 93 | + /** Gets the location of this variable. */ |
| 94 | + Location getLocation() { result = definingNode.getLocation() } |
| 95 | + |
| 96 | + /** Gets a textual representation of this variable. */ |
| 97 | + string toString() { result = this.getName() } |
| 98 | + |
| 99 | + /** Gets an access to this variable. */ |
| 100 | + VariableAccess getAnAccess() { result.getVariable() = this } |
| 101 | + } |
| 102 | + |
| 103 | + /** A path expression that may access a local variable. */ |
| 104 | + private class VariableAccessCand extends PathExpr { |
| 105 | + string name_; |
| 106 | + |
| 107 | + VariableAccessCand() { |
| 108 | + exists(Path p, PathSegment ps | |
| 109 | + p = this.getPath() and |
| 110 | + not p.hasQualifier() and |
| 111 | + ps = p.getPart() and |
| 112 | + not ps.hasGenericArgList() and |
| 113 | + not ps.hasParamList() and |
| 114 | + not ps.hasPathType() and |
| 115 | + not ps.hasReturnTypeSyntax() and |
| 116 | + name_ = ps.getNameRef().getText() |
| 117 | + ) |
| 118 | + } |
| 119 | + |
| 120 | + string getName() { result = name_ } |
| 121 | + } |
| 122 | + |
| 123 | + private AstNode getAnAncestorInVariableScope(AstNode n) { |
| 124 | + ( |
| 125 | + n instanceof Pat or |
| 126 | + n instanceof VariableAccessCand or |
| 127 | + n instanceof LetStmt or |
| 128 | + n instanceof VariableScope |
| 129 | + ) and |
| 130 | + exists(AstNode n0 | result = getImmediateParent(n0) | |
| 131 | + n0 = n |
| 132 | + or |
| 133 | + n0 = getAnAncestorInVariableScope(n) and |
| 134 | + not n0 instanceof VariableScope |
| 135 | + ) |
| 136 | + } |
| 137 | + |
| 138 | + /** Gets the immediately enclosing variable scope of `n`. */ |
| 139 | + private VariableScope getEnclosingScope(AstNode n) { result = getAnAncestorInVariableScope(n) } |
| 140 | + |
| 141 | + private Pat getAVariablePatAncestor(Variable v) { |
| 142 | + exists(AstNode definingNode, string name | |
| 143 | + v = MkVariable(definingNode, name) and |
| 144 | + variableDecl(definingNode, result, name) |
| 145 | + ) |
| 146 | + or |
| 147 | + exists(Pat mid | |
| 148 | + mid = getAVariablePatAncestor(v) and |
| 149 | + result = getImmediatePatParent(mid) |
| 150 | + ) |
| 151 | + } |
| 152 | + |
| 153 | + /** |
| 154 | + * Holds if `v` is named `name` and is declared inside variable scope |
| 155 | + * `scope`, and `v` is bound starting from `(line, column)`. |
| 156 | + */ |
| 157 | + private predicate variableDeclInScope( |
| 158 | + Variable v, VariableScope scope, string name, int line, int column |
| 159 | + ) { |
| 160 | + name = v.getName() and |
| 161 | + exists(Pat pat | pat = getAVariablePatAncestor(v) | |
| 162 | + scope = |
| 163 | + any(MatchArmScope arm | |
| 164 | + arm.getPat() = pat and |
| 165 | + arm.getLocation().hasLocationInfo(_, line, column, _, _) |
| 166 | + ) |
| 167 | + or |
| 168 | + exists(Function f | |
| 169 | + f.getParamList().getAParam().getPat() = pat and |
| 170 | + scope = f.getBody() and |
| 171 | + scope.getLocation().hasLocationInfo(_, line, column, _, _) |
| 172 | + ) |
| 173 | + or |
| 174 | + exists(LetStmt let | |
| 175 | + let.getPat() = pat and |
| 176 | + scope = getEnclosingScope(let) and |
| 177 | + // for `let` statements, variables are bound _after_ the statement, i.e. |
| 178 | + // not in the RHS |
| 179 | + let.getLocation().hasLocationInfo(_, _, _, line, column) |
| 180 | + ) |
| 181 | + or |
| 182 | + exists(IfExpr ie, LetExpr let | |
| 183 | + let.getPat() = pat and |
| 184 | + ie.getCondition() = let and |
| 185 | + scope = ie.getThen() and |
| 186 | + scope.getLocation().hasLocationInfo(_, line, column, _, _) |
| 187 | + ) |
| 188 | + or |
| 189 | + exists(ForExpr fe | |
| 190 | + fe.getPat() = pat and |
| 191 | + scope = fe.getLoopBody() and |
| 192 | + scope.getLocation().hasLocationInfo(_, line, column, _, _) |
| 193 | + ) |
| 194 | + or |
| 195 | + exists(ClosureExpr ce | |
| 196 | + ce.getParamList().getAParam().getPat() = pat and |
| 197 | + scope = ce.getBody() and |
| 198 | + scope.getLocation().hasLocationInfo(_, line, column, _, _) |
| 199 | + ) |
| 200 | + ) |
| 201 | + } |
| 202 | + |
| 203 | + /** |
| 204 | + * Holds if `cand` may access a variable named `name` at |
| 205 | + * `(startline, startcolumn, endline, endcolumn)` in the variable scope |
| 206 | + * `scope`. |
| 207 | + * |
| 208 | + * `nestLevel` is the number of nested scopes that need to be traversed |
| 209 | + * to reach `scope` from `cand`. |
| 210 | + */ |
| 211 | + private predicate variableAccessCandInScope( |
| 212 | + VariableAccessCand cand, VariableScope scope, string name, int nestLevel, int startline, |
| 213 | + int startcolumn, int endline, int endcolumn |
| 214 | + ) { |
| 215 | + name = cand.getName() and |
| 216 | + scope = [cand.(VariableScope), getEnclosingScope(cand)] and |
| 217 | + cand.getLocation().hasLocationInfo(_, startline, startcolumn, endline, endcolumn) and |
| 218 | + nestLevel = 0 |
| 219 | + or |
| 220 | + exists(VariableScope inner | |
| 221 | + variableAccessCandInScope(cand, inner, name, nestLevel - 1, _, _, _, _) and |
| 222 | + scope = getEnclosingScope(inner) and |
| 223 | + // Use the location of the inner scope as the location of the access, instead of the |
| 224 | + // actual access location. This allows us to collapse multiple accesses in inner |
| 225 | + // scopes to a single entity |
| 226 | + scope.getLocation().hasLocationInfo(_, startline, startcolumn, endline, endcolumn) |
| 227 | + ) |
| 228 | + } |
| 229 | + |
| 230 | + private newtype TVariableOrAccessCand = |
| 231 | + TVariableOrAccessCandVariable(Variable v) or |
| 232 | + TVariableOrAccessCandVariableAccessCand(VariableAccessCand va) |
| 233 | + |
| 234 | + private class VariableOrAccessCand extends TVariableOrAccessCand { |
| 235 | + Variable asVariable() { this = TVariableOrAccessCandVariable(result) } |
| 236 | + |
| 237 | + VariableAccessCand asVariableAccessCand() { |
| 238 | + this = TVariableOrAccessCandVariableAccessCand(result) |
| 239 | + } |
| 240 | + |
| 241 | + string toString() { |
| 242 | + result = this.asVariable().toString() or result = this.asVariableAccessCand().toString() |
| 243 | + } |
| 244 | + |
| 245 | + Location getLocation() { |
| 246 | + result = this.asVariable().getLocation() or result = this.asVariableAccessCand().getLocation() |
| 247 | + } |
| 248 | + |
| 249 | + pragma[nomagic] |
| 250 | + predicate rankBy( |
| 251 | + string name, VariableScope scope, int startline, int startcolumn, int endline, int endcolumn |
| 252 | + ) { |
| 253 | + variableDeclInScope(this.asVariable(), scope, name, startline, startcolumn) and |
| 254 | + endline = -1 and |
| 255 | + endcolumn = -1 |
| 256 | + or |
| 257 | + variableAccessCandInScope(this.asVariableAccessCand(), scope, name, _, startline, startcolumn, |
| 258 | + endline, endcolumn) |
| 259 | + } |
| 260 | + } |
| 261 | + |
| 262 | + /** |
| 263 | + * Gets the rank of `v` amongst all other declarations or access candidates |
| 264 | + * to a variable named `name` in the variable scope `scope`. |
| 265 | + */ |
| 266 | + private int rankVariableOrAccess(VariableScope scope, string name, VariableOrAccessCand v) { |
| 267 | + v = |
| 268 | + rank[result + 1](VariableOrAccessCand v0, int startline, int startcolumn, int endline, |
| 269 | + int endcolumn | |
| 270 | + v0.rankBy(name, scope, startline, startcolumn, endline, endcolumn) |
| 271 | + | |
| 272 | + v0 order by startline, startcolumn, endline, endcolumn |
| 273 | + ) |
| 274 | + } |
| 275 | + |
| 276 | + /** |
| 277 | + * Holds if `v` can reach rank `rnk` in the variable scope `scope`. This is needed to |
| 278 | + * take shadowing into account, for example in |
| 279 | + * |
| 280 | + * ```rust |
| 281 | + * let x = 0; // rank 0 |
| 282 | + * use(x); // rank 1 |
| 283 | + * let x = ""; // rank 2 |
| 284 | + * use(x); // rank 3 |
| 285 | + * ``` |
| 286 | + * |
| 287 | + * the declaration at rank 0 can only reach the access at rank 1, while the declaration |
| 288 | + * at rank 2 can only reach the access at rank 3. |
| 289 | + */ |
| 290 | + private predicate variableReachesRank(VariableScope scope, string name, Variable v, int rnk) { |
| 291 | + rnk = rankVariableOrAccess(scope, name, TVariableOrAccessCandVariable(v)) |
| 292 | + or |
| 293 | + variableReachesRank(scope, name, v, rnk - 1) and |
| 294 | + rnk = rankVariableOrAccess(scope, name, TVariableOrAccessCandVariableAccessCand(_)) |
| 295 | + } |
| 296 | + |
| 297 | + private predicate variableReachesCand( |
| 298 | + VariableScope scope, string name, Variable v, VariableAccessCand cand, int nestLevel |
| 299 | + ) { |
| 300 | + exists(int rnk | |
| 301 | + variableReachesRank(scope, name, v, rnk) and |
| 302 | + rnk = rankVariableOrAccess(scope, name, TVariableOrAccessCandVariableAccessCand(cand)) and |
| 303 | + variableAccessCandInScope(cand, scope, name, nestLevel, _, _, _, _) |
| 304 | + ) |
| 305 | + } |
| 306 | + |
| 307 | + /** A variable access. */ |
| 308 | + class VariableAccess extends PathExprImpl::PathExpr instanceof VariableAccessCand { |
| 309 | + private string name; |
| 310 | + private Variable v; |
| 311 | + |
| 312 | + VariableAccess() { variableAccess(_, name, v, this) } |
| 313 | + |
| 314 | + /** Gets the variable being accessed. */ |
| 315 | + Variable getVariable() { result = v } |
| 316 | + |
| 317 | + override string toString() { result = name } |
| 318 | + |
| 319 | + override string getAPrimaryQlClass() { result = "VariableAccess" } |
| 320 | + } |
| 321 | + |
| 322 | + cached |
| 323 | + private module Cached { |
| 324 | + cached |
| 325 | + newtype TVariable = |
| 326 | + MkVariable(AstNode definingNode, string name) { variableDecl(definingNode, _, name) } |
| 327 | + |
| 328 | + cached |
| 329 | + predicate variableAccess(VariableScope scope, string name, Variable v, VariableAccessCand cand) { |
| 330 | + v = |
| 331 | + min(Variable v0, int nestLevel | |
| 332 | + variableReachesCand(scope, name, v0, cand, nestLevel) |
| 333 | + | |
| 334 | + v0 order by nestLevel |
| 335 | + ) |
| 336 | + } |
| 337 | + } |
| 338 | + |
| 339 | + private import Cached |
| 340 | +} |
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