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MathiasVPMathiasVP
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Merge pull request #14495 from github/calumgrant/comp-generated-this
C++: Fix ImplicitThisFieldAccess
2 parents f562d53 + 8054a5d commit 6c10ba2

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+40
-37
lines changed

6 files changed

+40
-37
lines changed

‎cpp/ql/lib/change-notes/2023-10-20-implicit-this.md‎

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@@ -0,0 +1,4 @@
1+
---
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category: minorAnalysis
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---
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* More field accesses are identified as `ImplicitThisFieldAccess`.

‎cpp/ql/lib/semmle/code/cpp/exprs/Access.qll‎

Lines changed: 4 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -306,15 +306,13 @@ private predicate exprHasReferenceConversion(Expr e) { referenceConversion(e.get
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* }
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* };
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* ```
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* Note: the C++ front-end often automatically desugars `field` to
310-
* `this->field`, so most accesses of `this->field` are instances
311-
* of `PointerFieldAccess` (with `ThisExpr` as the qualifier), not
312-
* `ImplicitThisFieldAccess`.
313309
*/
314310
class ImplicitThisFieldAccess extends FieldAccess {
315311
override string getAPrimaryQlClass() { result = "ImplicitThisFieldAccess" }
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317-
ImplicitThisFieldAccess() { not exists(this.getQualifier()) }
313+
ImplicitThisFieldAccess() {
314+
this.getQualifier().(ThisExpr).isCompilerGenerated() or not exists(this.getQualifier())
315+
}
318316
}
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320318
/**
@@ -332,7 +330,7 @@ class PointerToFieldLiteral extends ImplicitThisFieldAccess {
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// access without a qualifier. The only other unqualified field accesses it
333331
// emits are for compiler-generated constructors and destructors. When we
334332
// filter those out, there are only pointer-to-field literals left.
335-
not this.isCompilerGenerated()
333+
not this.isCompilerGenerated() and not exists(this.getQualifier())
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}
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override predicate isConstant() { any() }

‎cpp/ql/lib/semmle/code/cpp/valuenumbering/HashCons.qll‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -372,7 +372,8 @@ private predicate analyzablePointerFieldAccess(PointerFieldAccess access) {
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private predicate mk_PointerFieldAccess(HashCons qualifier, Field target, PointerFieldAccess access) {
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analyzablePointerFieldAccess(access) and
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target = access.getTarget() and
375-
qualifier = hashCons(access.getQualifier().getFullyConverted())
375+
qualifier = hashCons(access.getQualifier().getFullyConverted()) and
376+
not access instanceof ImplicitThisFieldAccess
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}
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private predicate analyzableImplicitThisFieldAccess(ImplicitThisFieldAccess access) {

‎cpp/ql/test/examples/expressions/PrintAST.expected‎

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Original file line numberDiff line numberDiff line change
@@ -1298,7 +1298,7 @@ union_etc.cpp:
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# 6| getExpr(): [AssignExpr] ... = ...
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# 6| Type = [IntType] int
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# 6| ValueCategory = lvalue
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# 6| getLValue(): [PointerFieldAccess] x
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# 6| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 6| Type = [IntType] int
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# 6| ValueCategory = lvalue
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# 6| getQualifier(): [ThisExpr] this
@@ -1488,7 +1488,7 @@ union_etc.cpp:
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# 33| getExpr(): [AssignExpr] ... = ...
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# 33| Type = [IntType] int
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# 33| ValueCategory = lvalue
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# 33| getLValue(): [PointerFieldAccess] q
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# 33| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] q
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# 33| Type = [IntType] int
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# 33| ValueCategory = lvalue
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# 33| getQualifier(): [ThisExpr] this

‎cpp/ql/test/library-tests/access/FieldAccess/FieldAccess.expected‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
1-
| FieldAccess.cpp:11:12:11:13 | p1 | ptr |
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| FieldAccess.cpp:12:12:12:13 | p2 | ptr |
3-
| FieldAccess.cpp:25:12:25:13 | x1 | ptr |
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| FieldAccess.cpp:11:12:11:13 | p1 | ptr, this |
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| FieldAccess.cpp:12:12:12:13 | p2 | ptr, this |
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| FieldAccess.cpp:25:12:25:13 | x1 | ptr, this |
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| FieldAccess.cpp:29:18:29:19 | x2 | ptr |
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| FieldAccess.cpp:34:3:34:3 | d | this |
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| FieldAccess.cpp:45:13:45:14 | x1 | ptr |
@@ -19,10 +19,10 @@
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| FieldAccess.cpp:91:7:91:7 | x | val |
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| FieldAccess.cpp:91:13:91:13 | y | ref |
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| FieldAccess.cpp:92:8:92:8 | x | ptr |
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| FieldAccess.cpp:92:12:92:12 | y | ptr |
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| FieldAccess.cpp:92:12:92:12 | y | ptr, this |
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| FieldAccess.cpp:93:8:93:8 | x | ptr |
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| FieldAccess.cpp:93:18:93:18 | y | ptr |
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| FieldAccess.cpp:94:11:94:11 | y | ptr |
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| FieldAccess.cpp:94:20:94:20 | y | val |
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| FieldAccess.cpp:113:5:113:5 | x | ptr |
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| FieldAccess.cpp:113:5:113:5 | x | ptr, this |
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| FieldAccess.cpp:116:3:116:3 | v | this |

‎cpp/ql/test/library-tests/ir/ir/PrintAST.expected‎

Lines changed: 23 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -83,7 +83,7 @@ bad_asts.cpp:
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# 10| Type = [IntType] int
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# 10| Value = [Literal] 6
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# 10| ValueCategory = prvalue
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# 10| getRightOperand(): [PointerFieldAccess] x
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# 10| getRightOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 10| Type = [IntType] int
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# 10| ValueCategory = prvalue(load)
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# 10| getQualifier(): [ThisExpr] this
@@ -108,7 +108,7 @@ bad_asts.cpp:
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# 10| Type = [IntType] int
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# 10| Value = [Literal] t
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# 10| ValueCategory = prvalue
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# 10| getRightOperand(): [PointerFieldAccess] x
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# 10| getRightOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 10| Type = [IntType] int
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# 10| ValueCategory = prvalue(load)
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# 10| getQualifier(): [ThisExpr] this
@@ -5718,7 +5718,7 @@ ir.cpp:
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# 645| getExpr(): [AssignExpr] ... = ...
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# 645| Type = [IntType] int
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# 645| ValueCategory = lvalue
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# 645| getLValue(): [PointerFieldAccess] m_a
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# 645| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] m_a
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# 645| Type = [IntType] int
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# 645| ValueCategory = lvalue
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# 645| getQualifier(): [ThisExpr] this
@@ -5770,7 +5770,7 @@ ir.cpp:
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# 649| getLValue(): [VariableAccess] x
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# 649| Type = [IntType] int
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# 649| ValueCategory = lvalue
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# 649| getRValue(): [PointerFieldAccess] m_a
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# 649| getRValue(): [ImplicitThisFieldAccess,PointerFieldAccess] m_a
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# 649| Type = [IntType] int
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# 649| ValueCategory = prvalue(load)
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# 649| getQualifier(): [ThisExpr] this
@@ -9018,7 +9018,7 @@ ir.cpp:
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# 1043| getArrayBase(): [FunctionCall] call to c_str
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# 1043| Type = [PointerType] const char *
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# 1043| ValueCategory = prvalue
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# 1043| getQualifier(): [PointerFieldAccess] s
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# 1043| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
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# 1043| Type = [LValueReferenceType] const String &
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# 1043| ValueCategory = prvalue(load)
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# 1043| getQualifier(): [ThisExpr] this
@@ -9027,7 +9027,7 @@ ir.cpp:
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# 1043| getQualifier().getFullyConverted(): [ReferenceDereferenceExpr] (reference dereference)
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# 1043| Type = [SpecifiedType] const String
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# 1043| ValueCategory = lvalue
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# 1043| getArrayOffset(): [PointerFieldAccess] x
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# 1043| getArrayOffset(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 1043| Type = [LValueReferenceType] int &
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# 1043| ValueCategory = prvalue(load)
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# 1043| getQualifier(): [ThisExpr] this
@@ -9076,13 +9076,13 @@ ir.cpp:
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# 1045| getArrayBase(): [FunctionCall] call to c_str
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# 1045| Type = [PointerType] const char *
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# 1045| ValueCategory = prvalue
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# 1045| getQualifier(): [PointerFieldAccess] s
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# 1045| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
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# 1045| Type = [SpecifiedType] const String
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# 1045| ValueCategory = lvalue
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# 1045| getQualifier(): [ThisExpr] this
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# 1045| Type = [PointerType] const lambda [] type at line 1045, col. 21 *
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# 1045| ValueCategory = prvalue(load)
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# 1045| getArrayOffset(): [PointerFieldAccess] x
9085+
# 1045| getArrayOffset(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 1045| Type = [IntType] int
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# 1045| ValueCategory = prvalue(load)
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# 1045| getQualifier(): [ThisExpr] this
@@ -9114,7 +9114,7 @@ ir.cpp:
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# 1047| getArrayBase(): [FunctionCall] call to c_str
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# 1047| Type = [PointerType] const char *
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# 1047| ValueCategory = prvalue
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# 1047| getQualifier(): [PointerFieldAccess] s
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# 1047| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
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# 1047| Type = [LValueReferenceType] const String &
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# 1047| ValueCategory = prvalue(load)
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# 1047| getQualifier(): [ThisExpr] this
@@ -9167,7 +9167,7 @@ ir.cpp:
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# 1049| getArrayBase(): [FunctionCall] call to c_str
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# 1049| Type = [PointerType] const char *
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# 1049| ValueCategory = prvalue
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# 1049| getQualifier(): [PointerFieldAccess] s
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# 1049| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
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# 1049| Type = [SpecifiedType] const String
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# 1049| ValueCategory = lvalue
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# 1049| getQualifier(): [ThisExpr] this
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# 1051| getArrayBase(): [FunctionCall] call to c_str
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# 1051| Type = [PointerType] const char *
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# 1051| ValueCategory = prvalue
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# 1051| getQualifier(): [PointerFieldAccess] s
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# 1051| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
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# 1051| Type = [LValueReferenceType] const String &
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# 1051| ValueCategory = prvalue(load)
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# 1051| getQualifier(): [ThisExpr] this
@@ -9212,7 +9212,7 @@ ir.cpp:
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# 1051| getQualifier().getFullyConverted(): [ReferenceDereferenceExpr] (reference dereference)
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# 1051| Type = [SpecifiedType] const String
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# 1051| ValueCategory = lvalue
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# 1051| getArrayOffset(): [PointerFieldAccess] x
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# 1051| getArrayOffset(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 1051| Type = [IntType] int
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# 1051| ValueCategory = prvalue(load)
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# 1051| getQualifier(): [ThisExpr] this
@@ -9244,7 +9244,7 @@ ir.cpp:
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# 1054| getArrayBase(): [FunctionCall] call to c_str
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# 1054| Type = [PointerType] const char *
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# 1054| ValueCategory = prvalue
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# 1054| getQualifier(): [PointerFieldAccess] s
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# 1054| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
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# 1054| Type = [LValueReferenceType] const String &
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# 1054| ValueCategory = prvalue(load)
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# 1054| getQualifier(): [ThisExpr] this
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# 1054| getLeftOperand(): [AddExpr] ... + ...
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# 1054| Type = [IntType] int
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# 1054| ValueCategory = prvalue
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# 1054| getLeftOperand(): [PointerFieldAccess] x
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# 1054| getLeftOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] x
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# 1054| Type = [IntType] int
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# 1054| ValueCategory = prvalue(load)
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# 1054| getQualifier(): [ThisExpr] this
@@ -11490,7 +11490,7 @@ ir.cpp:
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# 1458| getExpr(): [AssignExpr] ... = ...
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# 1458| Type = [IntType] int
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# 1458| ValueCategory = lvalue
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# 1458| getLValue(): [PointerFieldAccess] y
11493+
# 1458| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] y
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# 1458| Type = [IntType] int
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# 1458| ValueCategory = lvalue
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# 1458| getQualifier(): [ThisExpr] this
@@ -12302,7 +12302,7 @@ ir.cpp:
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# 1567| <params>:
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# 1567| getEntryPoint(): [BlockStmt] { ... }
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# 1568| getStmt(0): [ReturnStmt] return ...
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# 1568| getExpr(): [PointerFieldAccess] i
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# 1568| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] i
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# 1568| Type = [IntType] int
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# 1568| ValueCategory = lvalue
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# 1568| getQualifier(): [ThisExpr] this
@@ -12315,7 +12315,7 @@ ir.cpp:
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# 1571| <params>:
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# 1571| getEntryPoint(): [BlockStmt] { ... }
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# 1572| getStmt(0): [ReturnStmt] return ...
12318-
# 1572| getExpr(): [PointerFieldAccess] d
12318+
# 1572| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] d
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# 1572| Type = [DoubleType] double
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# 1572| ValueCategory = lvalue
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# 1572| getQualifier(): [ThisExpr] this
@@ -12328,7 +12328,7 @@ ir.cpp:
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# 1575| <params>:
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# 1575| getEntryPoint(): [BlockStmt] { ... }
1233012330
# 1576| getStmt(0): [ReturnStmt] return ...
12331-
# 1576| getExpr(): [PointerFieldAccess] r
12331+
# 1576| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] r
1233212332
# 1576| Type = [LValueReferenceType] int &
1233312333
# 1576| ValueCategory = prvalue(load)
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# 1576| getQualifier(): [ThisExpr] this
@@ -12669,7 +12669,7 @@ ir.cpp:
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# 1633| <params>:
1267012670
# 1633| getEntryPoint(): [BlockStmt] { ... }
1267112671
# 1634| getStmt(0): [ReturnStmt] return ...
12672-
# 1634| getExpr(): [PointerFieldAccess] i
12672+
# 1634| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] i
1267312673
# 1634| Type = [IntType] int
1267412674
# 1634| ValueCategory = prvalue(load)
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# 1634| getQualifier(): [ThisExpr] this
@@ -12679,7 +12679,7 @@ ir.cpp:
1267912679
# 1637| <params>:
1268012680
# 1637| getEntryPoint(): [BlockStmt] { ... }
1268112681
# 1638| getStmt(0): [ReturnStmt] return ...
12682-
# 1638| getExpr(): [PointerFieldAccess] r
12682+
# 1638| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] r
1268312683
# 1638| Type = [LValueReferenceType] int &
1268412684
# 1638| ValueCategory = prvalue(load)
1268512685
# 1638| getQualifier(): [ThisExpr] this
@@ -13290,7 +13290,7 @@ ir.cpp:
1329013290
# 1703| getQualifier(): [AddressOfExpr] & ...
1329113291
# 1703| Type = [PointerType] const TrivialLambdaClass *
1329213292
# 1703| ValueCategory = prvalue
13293-
# 1703| getOperand(): [PointerFieldAccess] (captured this)
13293+
# 1703| getOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] (captured this)
1329413294
# 1703| Type = [SpecifiedType] const TrivialLambdaClass
1329513295
# 1703| ValueCategory = lvalue
1329613296
# 1703| getQualifier(): [ThisExpr] this
@@ -13337,7 +13337,7 @@ ir.cpp:
1333713337
# 1706| getQualifier(): [AddressOfExpr] & ...
1333813338
# 1706| Type = [PointerType] const TrivialLambdaClass *
1333913339
# 1706| ValueCategory = prvalue
13340-
# 1706| getOperand(): [PointerFieldAccess] (captured this)
13340+
# 1706| getOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] (captured this)
1334113341
# 1706| Type = [SpecifiedType] const TrivialLambdaClass
1334213342
# 1706| ValueCategory = lvalue
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# 1706| getQualifier(): [ThisExpr] this
@@ -13480,7 +13480,7 @@ ir.cpp:
1348013480
# 1726| getExpr(): [AssignExpr] ... = ...
1348113481
# 1726| Type = [IntType] int
1348213482
# 1726| ValueCategory = lvalue
13483-
# 1726| getLValue(): [PointerFieldAccess] x
13483+
# 1726| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] x
1348413484
# 1726| Type = [IntType] int
1348513485
# 1726| ValueCategory = lvalue
1348613486
# 1726| getQualifier(): [ThisExpr] this

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