Move older change notes to old-change-notes

Now that change notes are per-package, new change notes should be created in the `change-notes` folder under the affected pack (e.g., `cpp/ql/src/change-notes` for C++ query change notes. I've moved all of the change note files that were added before we started publishing them in packs to an `old-change-notes` directory under each language, to reduce the temptation to add new change notes there.

I'm working on a document to describe how and when to create change notes for packs separately.

cpp/old-change-notes/2020-09-29-range-analysis-rollup.md

@@ -0,0 +1,14 @@
+lgtm,codescanning
+* The `SimpleRangeAnalysis` library has gained support for several language
+  constructs it did not support previously. These improvements primarily affect
+  the queries `cpp/constant-comparison`, `cpp/comparison-with-wider-type`, and
+  `cpp/integer-multiplication-cast-to-long`. The newly supported language
+  features are:
+    * Multiplication of unsigned numbers.
+    * Multiplication by a constant.
+    * Reference-typed function parameters.
+    * Comparing a variable not equal to an endpoint of its range, thus narrowing the range by one.
+    * Using `if (x)` or `if (!x)` or similar to test for equality to zero.
+* The `SimpleRangeAnalysis` library can now be extended with custom rules. See
+  examples in
+  `cpp/ql/src/experimental/semmle/code/cpp/rangeanalysis/extensions/`.

cpp/old-change-notes/2020-10-21-erroneous-types.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The `cpp/wrong-type-format-argument` and `cpp/non-portable-printf` queries have been hardened so that they do not produce nonsensical results on databases that contain errors (specifically the `ErroneousType`).

cpp/old-change-notes/2020-10-21-size-check-queries.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Not enough memory allocated for pointer type' (cpp/allocation-too-small) and 'Not enough memory allocated for array of pointer type' (cpp/suspicious-allocation-size) queries have been improved. Previously some allocations would be reported by both queries, this no longer occurs. In addition more allocation functions are now understood by both queries.

cpp/old-change-notes/2020-11-02-unused-local-variable.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Two issues causing the 'Unused local variable' query (`cpp/unused-local-variable`) to produce false positive results have been fixed.

cpp/old-change-notes/2020-11-05-formatting-function.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* `FormattingFunction.getOutputParameterIndex` now has a parameter identifying whether the output at that index is a buffer or a stream.
+* `FormattingFunction` now has a predicate `isOutputGlobal` indicating when the output is to a global stream.
+* The `primitiveVariadicFormatter` and `variadicFormatter` predicates have more parameters exposing information about the function.

cpp/old-change-notes/2020-11-05-private-models.md

@@ -0,0 +1,3 @@
+lgtm,codescanning
+* Various classes in `semmle.code.cpp.models.implementations` have been made private. Users should not depend on library implementation details.
+* The `OperatorNewAllocationFunction`, `OperatorDeleteDeallocationFunction`, `Iterator` and `Snprintf` classes now have interfaces in `semmle.code.cpp.models.interfaces`.

cpp/old-change-notes/2020-11-12-unsafe-use-of-this.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* A new query (`cpp/unsafe-use-of-this`) has been added. The query finds pure virtual function calls whose qualifier is an object under construction.

cpp/old-change-notes/2020-11-27-downgrade-to-recommendation.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The queries `cpp/local-variable-hides-global-variable` and `cpp/missing-header-guard` now have severity `recommendation` instead of `warning`.

cpp/old-change-notes/2021-02-04-unsigned-difference-expression-compared-zero.md

@@ -0,0 +1,2 @@
+lgtm
+* A new query (`cpp/unsigned-difference-expression-compared-zero`) is run but not yet displayed on LGTM. The query finds unsigned subtractions used in relational comparisons with the value 0. This query was originally submitted as an experimental query by @ihsinme in https://github.com/github/codeql/pull/4745.

cpp/old-change-notes/2021-02-24-memset-may-be-deleted.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* A new query (`cpp/memset-may-be-deleted`) is added to the default query suite. The query finds calls to `memset` that may be removed by the compiler. This behavior can make information-leak vulnerabilities easier to exploit. This query was originally [submitted as an experimental query by @ihsinme](https://github.com/github/codeql/pull/4953).

cpp/old-change-notes/2021-03-01-fluent-interface-data-flow.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The data-flow library now recognises more side-effects of method chaining (e.g. `someObject.setX(clean).setY(tainted).setZ...` having a side-effect on `someObject`), as well as other related circumstances where a function input is directly passed to its output. All queries that use data-flow analysis, including most security queries, may return more results accordingly.

cpp/old-change-notes/2021-03-11-failed-extractions.md

@@ -0,0 +1,2 @@
+codescanning
+* Added cpp/diagnostics/failed-extractions. This query gives information about which extractions did not run to completion.

cpp/old-change-notes/2021-03-11-overflow-abs.md

@@ -0,0 +1,2 @@
+lgtm
+* The `cpp/tainted-arithmetic`, `cpp/arithmetic-with-extreme-values`, and `cpp/uncontrolled-arithmetic` queries now recognize more functions as returning the absolute value of their input. As a result, they produce fewer false positives.

cpp/old-change-notes/2021-03-17-av-rule-79.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Resource not released in destructor' (cpp/resource-not-released-in-destructor) query has been improved to recognize more releases of resources.

cpp/old-change-notes/2021-04-06-assign-where-compare-meant.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Assignment where comparison was intended' (cpp/assign-where-compare-meant) query has been improved to flag fewer benign assignments in conditionals.

cpp/old-change-notes/2021-04-09-unsigned-difference-expression-compared-zero.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Unsigned difference expression compared to zero' (cpp/unsigned-difference-expression-compared-zero) query has been improved to produce fewer false positive results.

cpp/old-change-notes/2021-04-13-arithmetic-queries.md

@@ -0,0 +1,2 @@
+lgtm
+* The queries cpp/tainted-arithmetic, cpp/uncontrolled-arithmetic, and cpp/arithmetic-with-extreme-values have been improved to produce fewer false positives.

cpp/old-change-notes/2021-04-21-return-stack-allocated-object.md

@@ -0,0 +1,2 @@
+codescanning
+* The 'Pointer to stack object used as return value' (cpp/return-stack-allocated-object) query has been deprecated, and any uses should be replaced with `Returning stack-allocated memory` (cpp/return-stack-allocated-memory).

cpp/old-change-notes/2021-04-26-more-sound-expr-might-overflow.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The `exprMightOverflowPositively` and `exprMightOverflowNegatively` predicates from the `SimpleRangeAnalysis` library now recognize more expressions that might overflow.

cpp/old-change-notes/2021-05-10-comparison-with-wider-type.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Comparison with wider type' (cpp/comparison-with-wider-type) query has been improved to produce fewer false positives.

cpp/old-change-notes/2021-05-12-uncontrolled-arithmetic.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The query "Uncontrolled arithmetic" (`cpp/uncontrolled-arithmetic`) has been improved to produce fewer false positives.

cpp/old-change-notes/2021-05-14-uncontrolled-allocation-size.md

@@ -0,0 +1,2 @@
+lgtm
+* The "Tainted allocation size" query (cpp/uncontrolled-allocation-size) has been improved to produce fewer false positives.

cpp/old-change-notes/2021-05-18-static-buffer-overflow.md

@@ -0,0 +1,2 @@
+lgtm
+* The "Static buffer overflow" query (cpp/static-buffer-overflow) has been improved to produce fewer false positives.

cpp/old-change-notes/2021-05-19-weak-cryptographic-algorithm.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The "Use of a broken or risky cryptographic algorithm" (`cpp/weak-cryptographic-algorithm`) query has been enhanced to reduce false positive results, and (rarely) find more true positive results.

cpp/old-change-notes/2021-05-20-incorrect-allocation-error-handling.md

@@ -0,0 +1,2 @@
+lgtm
+* A new query (`cpp/incorrect-allocation-error-handling`) has been added. The query finds incorrect error-handling of calls to `operator new`. This query was originally [submitted as an experimental query by @ihsinme](https://github.com/github/codeql/pull/5010).

cpp/old-change-notes/2021-05-20-ref-qualifiers.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* lvalue/rvalue ref qualifiers are now accessible via the new predicates on `MemberFunction`(`.isLValueRefQualified`, `.isRValueRefQualified`, and `isRefQualified`).

cpp/old-change-notes/2021-05-21-unsafe-strncat.md

@@ -0,0 +1,2 @@
+lgtm
+* The "Potentially unsafe call to strncat" query (cpp/unsafe-strncat) query has been improved to detect more cases of unsafe calls to `strncat`.

cpp/old-change-notes/2021-06-10-cleartext-transmission.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* A new query (`cpp/cleartext-transmission`) has been added. This is similar to the `cpp/cleartext-storage-file`, `cpp/cleartext-storage-buffer` and `cpp/cleartext-storage-database` queries but looks for cases where sensitive information is most likely transmitted over a network.

cpp/old-change-notes/2021-06-10-std-types.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* Added definitions for types found in `cstdint`. Added types `FixedWidthIntegralType`, `MinimumWidthIntegralType`, `FastestMinimumWidthIntegralType`, and `MaximumWidthIntegralType` to describe types such as `int8_t`, `int_least8_t`, `int_fast8_t`, and `intmax_t` respectively. 
+* Changed definition of `Intmax_t` and `Uintmax_t` to be part of the new type structure. 
+* Added a type `FixedWidthEnumType` which describes enums based on a fixed-width integer type. For instance, `enum e: uint8_t = { a, b };`.

cpp/old-change-notes/2021-06-21-weak-cryptographic-algorithm.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The "Use of a broken or risky cryptographic algorithm" (`cpp/weak-cryptographic-algorithm`) query has been further improved to reduce false positives and its `@precision` increased to `high`.

cpp/old-change-notes/2021-06-22-sql-tainted.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Uncontrolled data in SQL query' (cpp/sql-injection) query now supports the `libpqxx` library.

cpp/old-change-notes/2021-06-24-dataflow-implicit-reads.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The DataFlow libraries have been augmented with support for `Configuration`-specific in-place read steps at, for example, sinks and custom taint steps. This means that it is now possible to specify sinks that accept flow with non-empty access paths.

cpp/old-change-notes/2021-06-24-uncontrolled-arithmetic.md

@@ -0,0 +1,2 @@
+lgtm
+* The 'Uncontrolled data in arithmetic expression' (cpp/uncontrolled-arithmetic) query now recognizes more sources of randomness.

cpp/old-change-notes/2021-06-30-wrong-type-format-argument.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The 'Wrong type of arguments to formatting function' (cpp/wrong-type-format-argument) query is now more accepting of the string and character formatting differences between Microsoft and non-Microsoft platforms.  There are now fewer false positive results.

cpp/old-change-notes/2021-07-13-cleartext-storage-file.md

@@ -0,0 +1,3 @@
+lgtm,codescanning
+* The "Cleartext storage of sensitive information in file" (cpp/cleartext-storage-file) query now uses dataflow to produce additional results.
+* Heuristics in the SensitiveExprs.qll library have been improved, making the "Cleartext storage of sensitive information in file" (cpp/cleartext-storage-file), "Cleartext storage of sensitive information in buffer" (cpp/cleartext-storage-buffer) and "Cleartext storage of sensitive information in an SQLite" (cpp/cleartext-storage-database) queries more accurate.

cpp/old-change-notes/2021-07-20-toctou-race-condition.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Improvements have been made to the `cpp/toctou-race-condition` query, both to find more correct results and fewer false positive results.

cpp/old-change-notes/2021-07-27-uncontrolled-arithmetic.md

@@ -0,0 +1,2 @@
+lgtm
+* Improvements made to the (`cpp/uncontrolled-arithmetic`) query, reducing the frequency of false positive results.

cpp/old-change-notes/2021-07-29-virtual-function-declaration-specifiers.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Virtual function specifiers are now accessible via the new predicates on `Function` (`.isDeclaredVirtual`, `.isOverride`, and `.isFinal`).

cpp/old-change-notes/2021-08-10-has-trailing-return-type.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Added `Function.hasTrailingReturnType` predicate to check whether a function was declared with a trailing return type.

cpp/old-change-notes/2021-08-17-has-c-linkage.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Added `RoutineType.hasCLinkage` predicate to check whether a function type has "C" language linkage.

cpp/old-change-notes/2021-08-23-ctime-weaken-claims.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Lowered the precision of `cpp/potentially-dangerous-function` so it is run but not displayed on LGTM by default and so it's only run and displayed on Code Scanning if a broader suite like `cpp-security-extended` is opted into.

cpp/old-change-notes/2021-08-23-getPrimaryQlClasses.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Added `Element.getPrimaryQlClasses()` predicate, which gets a comma-separated list of the names of the primary CodeQL classes to which this element belongs.

cpp/old-change-notes/2021-08-24-implicit-downcast-from-bitfield.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The query `cpp/implicit-bitfield-downcast` now accounts for C++ reference types, which leads to more true positive results.

cpp/old-change-notes/2021-08-31-range-analysis-upper-bound.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* The `SimpleRangeAnalysis` library includes information from the
+  immediate guard for determining the upper bound of a stack
+  variable for improved accuracy.

cpp/old-change-notes/2021-09-13-overflow-static.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* The `memberMayBeVarSize` predicate considers more fields to be variable size.
+  As a result, the "Static buffer overflow" query (cpp/static-buffer-overflow)
+  produces fewer false positives.

cpp/old-change-notes/2021-09-27-command-line-injection.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The "Uncontrolled data used in OS command" (`cpp/command-line-injection`) query has been enhanced to reduce false positive results and its `@precision` increased to `high`

cpp/old-change-notes/2021-09-27-overflow-static.md

@@ -0,0 +1,3 @@
+lgtm,codescanning
+* Increase precision to high for the "Static buffer overflow" query
+  (`cpp/static-buffer-overflow`). This means the query is run and displayed by default on Code Scanning and LGTM.

cpp/old-change-notes/2021-10-01-improper-null-termination.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Several improvements made to the `NullTermination.qll` library and the 'Potential improper null termination' (cpp/improper-null-termination). These changes reduce the number of false positive results for this query and related query 'User-controlled data may not be null terminated' (cpp/user-controlled-null-termination-tainted).

cpp/old-change-notes/2021-10-07-extraction-errors.md

@@ -0,0 +1,3 @@
+codescanning
+* Problems with extraction that in most cases won't break the analysis in a significant way are now reported as warnings rather than errors.
+* The failed extractor invocations query now has severity `error`.