2.3. Configuring the Analyzer — Clang 21.1.1 documentation

# Clang 21.1.1 documentation

## 2.3. Configuring the Analyzer

The clang static analyzer supports two kinds of options:

1. Global analyzer options influence the behavior of the analyzer engine. They are documented on this page, in the section List of analyzer options.

2. The checker options belong to individual checkers (e.g. `core.BitwiseShift:Pedantic` and `unix.Stream:Pedantic` are completely separate options) and customize the behavior of that particular checker. These are documented within the documentation of each individual checker at Available Checkers.

## 2.3.1. Assigning values to options

### 2.3.1.1. With the compiler frontend

All options can be configured by using the `-analyzer-config` flag of `clang -cc1` (the so-called compiler frontend part of clang). The values of the options are specified with the syntax `-analyzer-config OPT=VAL,OPT2=VAL2,...` which supports specifying multiple options, but separate flags like `-analyzer-config OPT=VAL -analyzer-config OPT2=VAL2` are also accepted (with equivalent behavior). Analyzer options and checker options can be freely intermixed here because it’s easy to recognize that checker option names are always prefixed with `some.groups.NameOfChecker:`.

Warning

This is an internal interface, one should prefer clang –analyze … for regular use. Clang does not intend to preserve backwards compatibility or announce breaking changes within the flags accepted by `clang -cc1` (but `-analyzer-config` survived many years without major changes).

### 2.3.1.2. With the clang driver

In a conventional workflow `clang -cc1` (which is a low-level internal interface) is invoked indirectly by the clang driver (i.e. plain `clang` without the `-cc1` flag), which acts as an “even more frontend” wrapper layer around the `clang -cc1` compiler frontend. In this situation each command line argument intended for the compiler frontend must be prefixed with `-Xclang`.

For example the following command analyzes `foo.c` in shallow mode with loop unrolling:

    clang --analyze -Xclang -analyzer-config -Xclang mode=shallow,unroll-loops=true foo.c

When this is executed, the driver will compose and execute the following `clang -cc1` command (which can be inspected by passing the `-v` flag to the driver):

    clang -cc1 -analyze [...] -analyzer-config mode=shallow,unroll-loops=true foo.c

Here `[...]` stands for dozens of low-level flags which ensure that `clang -cc1` does the right thing (e.g. `-fcolor-diagnostics` when it’s suitable; `-analyzer-checker` flags to enable the default set of checkers). Also note the distinction that the `clang` driver requires `--analyze` (double dashes) while the `clang -cc1` compiler frontend requires `-analyze` (single dash).

Note

The flag `-Xanalyzer` is equivalent to `-Xclang` in these situations (but doesn’t forward other options of the clang frontend).

### 2.3.1.3. With CodeChecker

If the analysis is performed through CodeChecker (which e.g. supports the analysis of a whole project instead of a single file) then it will act as another indirection layer. CodeChecker provides separate command-line flags called `--analyzer-config` (for analyzer options) and `--checker-config` (for checker options):

    CodeChecker analyze -o outdir --checker-config clangsa:unix.Stream:Pedantic=true  \
            --analyzer-config clangsa:mode=shallow clangsa:unroll-loops=true          \
            -- compile_commands.json

These CodeChecker flags may be followed by multiple `OPT=VAL` pairs as separate arguments (and this is why the example needs to use `--` before `compile_commands.json`). The option names are all prefixed with `clangsa:` to ensure that they are passed to the clang static analyzer (and not other analyzer tools that are also supported by CodeChecker).

## 2.3.2. List of analyzer options

Warning

These options are primarily intended for development purposes and non-default values are usually unsupported. Changing their values may drastically alter the behavior of the analyzer, and may even result in instabilities or crashes! Crash reports are welcome and depending on the severity they may be fixed.

### 2.3.2.1. mode

(string) Controls the high-level analyzer mode, which influences the default settings for some of the lower-level config options (such as IPAMode).

Accepted values: “deep”, “shallow”.

Default value: “deep”

### 2.3.2.2. cfg-implicit-dtors

Whether or not implicit destructors for C++ objects should be included in the CFG.

Default value: true

### 2.3.2.3. cfg-temporary-dtors

Whether or not the destructors for C++ temporary objects should be included in the CFG.

Default value: true

### 2.3.2.4. cfg-lifetime

Whether or not end-of-lifetime information should be included in the CFG.

Default value: false

### 2.3.2.5. cfg-loopexit

Whether or not the end of the loop information should be included in the CFG.

Default value: false

### 2.3.2.6. cfg-rich-constructors

Whether or not construction site information should be included in the CFG C++ constructor elements.

Default value: true

### 2.3.2.7. cfg-scopes

Whether or not scope information should be included in the CFG.

Default value: false

### 2.3.2.8. cfg-expand-default-aggr-inits

Whether or not inline CXXDefaultInitializers for aggregate initialization in the CFG.

Default value: false

### 2.3.2.9. c++-template-inlining

Whether or not templated functions may be considered for inlining.

Default value: true

### 2.3.2.10. c++-stdlib-inlining

Whether or not C++ standard library functions may be considered for inlining.

Default value: true

### 2.3.2.11. c++-allocator-inlining

Whether or not allocator and deallocator calls may be considered for inlining.

Default value: true

### 2.3.2.12. c++-shared_ptr-inlining

Whether or not the destructor of C++ ‘shared_ptr’ may be considered for inlining. This covers std::shared_ptr, std::tr1::shared_ptr, and boost::shared_ptr, and indeed any destructor named ‘~shared_ptr’.

Default value: false

### 2.3.2.13. c++-temp-dtor-inlining

Whether C++ temporary destructors should be inlined during analysis. If temporary destructors are disabled in the CFG via the ‘cfg-temporary-dtors’ option, temporary destructors would not be inlined anyway.

Default value: true

### 2.3.2.14. suppress-null-return-paths

Whether or not paths that go through null returns should be suppressed. This is a heuristic for avoiding bug reports with paths that go through inlined functions that are more defensive than their callers.

Default value: true

### 2.3.2.15. avoid-suppressing-null-argument-paths

Whether a bug report should not be suppressed if its path includes a call with a null argument, even if that call has a null return. This option has no effect when ShouldSuppressNullReturnPaths is false. This is a counter-heuristic to avoid false negatives.

Default value: false

### 2.3.2.16. suppress-inlined-defensive-checks

Whether or not diagnostics containing inlined defensive NULL checks should be suppressed.

Default value: true

### 2.3.2.17. c++-container-inlining

Whether or not methods of C++ container objects may be considered for inlining.

Default value: false

### 2.3.2.18. suppress-c++-stdlib

Whether or not diagnostics reported within the C++ standard library should be suppressed.

Default value: true

### 2.3.2.19. crosscheck-with-z3

Whether bug reports should be crosschecked with the Z3 constraint manager backend.

Default value: false

### 2.3.2.20. crosscheck-with-z3-eqclass-timeout-threshold

Set a timeout for bug report equivalence classes in milliseconds. If we exhaust this threshold, we will drop the bug report eqclass instead of doing more Z3 queries. Setting this to 700 ms in conjunction with “crosscheck-with-z3-timeout- threshold” of 300 ms, would nicely guarantee that no bug report equivalence class can take longer than 1 second, effectively mitigating Z3 hangs during refutation. If there were Z3 retries, only the minimum query time is considered when accumulating query times within a report equivalence class. Set 0 for no timeout.

Default value: 0

### 2.3.2.21. crosscheck-with-z3-timeout-threshold

Set a timeout for individual Z3 queries in milliseconds. On fast machines, 300 worked well in some cases. The lower it is, the higher the chances of having flaky issues. Having no timeout may hang the analyzer indefinitely. Set 0 for no timeout.

Default value: 15000

### 2.3.2.22. crosscheck-with-z3-rlimit-threshold

Set the Z3 resource limit threshold. This sets a supposedly deterministic cutoff point for Z3 queries, as longer queries usually consume more resources. 400’000 should on average make Z3 queries run for up to 100ms on modern hardware. Set 0 for unlimited.

Default value: 0

### 2.3.2.23. crosscheck-with-z3-max-attempts-per-query

Set how many times the oracle is allowed to run a Z3 query. This must be a positive value. Set 1 to not allow any retry attempts. Increasing the number of attempts is often more effective at reducing the number of nondeterministic diagnostics than “crosscheck-with-z3-timeout-threshold” in practice.

Default value: 3

### 2.3.2.24. report-in-main-source-file

Whether or not the diagnostic report should be always reported in the main source file and not the headers.

Default value: false

### 2.3.2.25. stable-report-filename

Deprecated: report filenames are now always stable. See also ‘verbose-report- filename’.

Default value: false

### 2.3.2.26. verbose-report-filename

Whether or not the report filename should contain extra information about the issue.

Default value: false

### 2.3.2.27. serialize-stats

Whether the analyzer should serialize statistics to plist output. Statistics would be serialized in JSON format inside the main dictionary under the statistics key. Available only if compiled in assert mode or with LLVM statistics explicitly enabled.

Default value: false

### 2.3.2.28. objc-inlining

Whether ObjectiveC inlining is enabled, false otherwise.

Default value: true

### 2.3.2.29. prune-paths

Whether irrelevant parts of a bug report path should be pruned out of the final output.

Default value: true

### 2.3.2.30. add-pop-up-notes

Whether pop-up notes should be added to the final output.

Default value: true

### 2.3.2.31. cfg-conditional-static-initializers

Whether ‘static’ initializers should be in conditional logic in the CFG.

Default value: true

### 2.3.2.32. faux-bodies

Whether the analyzer engine should synthesize fake bodies for well-known functions.

Default value: true

### 2.3.2.33. elide-constructors

Whether elidable C++ copy-constructors and move-constructors should be actually elided during analysis. Both behaviors are allowed by the C++ standard, and the analyzer, like CodeGen, defaults to eliding. Starting with C++17 some elisions become mandatory, and in these cases the option will be ignored.

Default value: true

### 2.3.2.34. inline-lambdas

Whether lambdas should be inlined. Otherwise a sink node will be generated each time a LambdaExpr is visited.

Default value: true

### 2.3.2.35. widen-loops

Whether the analysis should try to widen loops.

Default value: false

### 2.3.2.36. unroll-loops

Whether the analysis should try to unroll loops with known bounds.

Default value: false

### 2.3.2.37. assume-at-least-one-iteration

Whether the analyzer should always assume at least one iteration in loops where the loop condition is opaque (i.e. the analyzer cannot determine if it’s true or false). Setting this to true eliminates some false positives (where e.g. a structure is nonempty, but the analyzer does not notice this); but it also eliminates some true positives (e.g. cases where a structure can be empty and this causes buggy behavior).

Default value: false

### 2.3.2.38. notes-as-events

Whether the bug reporter should transparently treat extra note diagnostic pieces as event diagnostic pieces. Useful when the diagnostic consumer doesn’t support the extra note pieces.

Default value: false

### 2.3.2.39. aggressive-binary-operation-simplification

Whether SValBuilder should rearrange comparisons and additive operations of symbolic expressions which consist of a sum of a symbol and a concrete integer into the format where symbols are on the left-hand side and the integer is on the right. This is only done if both symbols and both concrete integers are signed, greater than or equal to the quarter of the minimum value of the type and less than or equal to the quarter of the maximum value of that type. A + n <OP> B + m becomes A - B <OP> m - n, where A and B symbolic, n and m are integers. <OP> is any of ‘==’, ‘!=’, ‘<’, ‘<=’, ‘>’, ‘>=’, ‘+’ or ‘-’. The rearrangement also happens with ‘-’ instead of ‘+’ on either or both side and also if any or both integers are missing.

Default value: false

### 2.3.2.40. eagerly-assume

If this is enabled (the default behavior), when the analyzer encounters a comparison operator or logical negation, it immediately splits the state to separate the case when the expression is true and the case when it’s false. The upside is that this can increase analysis precision until we have a better way to lazily evaluate such logic; the downside is that it eagerly bifurcates paths.

Default value: true

### 2.3.2.41. experimental-enable-naive-ctu-analysis

Whether naive cross translation unit analysis is enabled. This is an experimental feature to inline functions from other translation units.

Default value: false

### 2.3.2.42. expand-macros

Whether macros related to the bugpath should be expanded and included in the plist output.

Default value: false

### 2.3.2.43. display-ctu-progress

Whether to emit verbose output about the analyzer’s progress related to ctu.

Default value: false

### 2.3.2.44. dump-entry-point-stats-to-csv

If provided, the analyzer will dump statistics per entry point into the specified CSV file.

Default value: (empty string)

### 2.3.2.45. track-conditions

Whether to track conditions that are a control dependency of an already tracked variable.

Default value: true

### 2.3.2.46. track-conditions-debug

Whether to place an event at each tracked condition.

Default value: false

### 2.3.2.47. apply-fixits

Apply the fix-it hints to the files

Default value: false

### 2.3.2.48. display-checker-name

Display the checker name for textual outputs

Default value: true

### 2.3.2.49. support-symbolic-integer-casts

Produce cast symbols for integral types.

Default value: false

### 2.3.2.50. assume-controlled-environment

Whether the analyzed application runs in a controlled environment. We will assume that environment variables exist in queries and they hold no malicious data. For instance, if this option is enabled, ‘getenv()’ might be modeled by the analyzer to never return NULL.

Default value: false

### 2.3.2.51. ignore-bison-generated-files

If enabled, any files containing the “/* A Bison parser, made by” won’t be analyzed.

Default value: true

### 2.3.2.52. ignore-flex-generated-files

If enabled, any files containing the “/* A lexical scanner generated by flex” won’t be analyzed.

Default value: true

### 2.3.2.53. suppress-dereferences-from-any-address-space

The analyzer does not report dereferences on memory that use address space #256, #257, and #258. Those address spaces are used when dereferencing address spaces relative to the GS, FS, and SS segments on x86/x86-64 targets. Dereferencing a null pointer in these address spaces is not defined as an error. All other null dereferences in other address spaces are defined as an error unless explicitly defined. When this option is turned on, the special behavior of address spaces #256, #257, #258 is extended to all pointers with address spaces and on any target.

Default value: true

### 2.3.2.54. inline-functions-with-ambiguous-loops

If disabled (the default), the analyzer puts functions on a “do not inline this” list if it finds an execution path within that function that may potentially perform ‘analyzer-max-loop’ (= 4 by default) iterations in a loop. (Note that functions that _definitely_ reach the loop limit on some execution path are currently marked as “do not inline” even if this option is enabled.) Enabling this option eliminates this (somewhat arbitrary) restriction from the analysis scope, which increases the analysis runtime (on average by ~10%, but a few translation units may see much larger slowdowns).

Default value: false

### 2.3.2.55. ipa-always-inline-size

The size of the functions (in basic blocks), which should be considered to be small enough to always inline.

Default value: 3

### 2.3.2.56. graph-trim-interval

How often nodes in the ExplodedGraph should be recycled to save memory. To disable node reclamation, set the option to 0.

Default value: 1000

### 2.3.2.57. min-cfg-size-treat-functions-as-large

The number of basic blocks a function needs to have to be considered large for the ‘max-times-inline-large’ config option.

Default value: 14

### 2.3.2.58. max-symbol-complexity

The maximum complexity of symbolic constraint.

Default value: 35

### 2.3.2.59. max-tainted-symbol-complexity

[DEPRECATED] The maximum complexity of a symbol to carry taint

Default value: 9

### 2.3.2.60. max-times-inline-large

The maximum times a large function could be inlined.

Default value: 32

### 2.3.2.61. max-inlinable-size

The bound on the number of basic blocks in an inlined function.

Default value: 4 (in shallow mode) / 100 (in deep mode)

### 2.3.2.62. max-nodes

The maximum number of nodes the analyzer can generate while exploring a top level function (for each exploded graph). 0 means no limit.

Default value: 75000 (in shallow mode) / 225000 (in deep mode)

### 2.3.2.63. ctu-max-nodes-pct

The percentage of single-TU analysed nodes that the CTU analysis is allowed to visit.

Default value: 50

### 2.3.2.64. ctu-max-nodes-min

The maximum number of nodes in CTU mode is determinded by ‘ctu-max-nodes-pct’. However, if the number of nodes in single-TU analysis is too low, it is meaningful to provide a minimum value that serves as an upper bound instead.

Default value: 10000

### 2.3.2.65. region-store-small-struct-limit

The largest number of fields a struct can have and still be considered small. This is currently used to decide whether or not it is worth forcing a LazyCompoundVal on bind. To disable all small-struct-dependent behavior, set the option to 0.

Default value: 2

### 2.3.2.66. region-store-small-array-limit

The largest number of elements an array can have and still be considered small. This is currently used to decide whether or not it is worth forcing a LazyCompoundVal on bind. To disable all small-array-dependent behavior, set the option to 0.

Default value: 5

### 2.3.2.67. region-store-max-binding-fanout

This option limits how many sub-bindings a single binding operation can scatter into. For example, binding an array would scatter into binding each individual element. Setting this to zero means unlimited, but then modelling large array initializers may take proportional time to their size.

Default value: 128

### 2.3.2.68. ctu-dir

The directory containing the CTU related files.

Default value: (empty string)

### 2.3.2.69. ctu-index-name

The name of the file containing the CTU index of definitions. The index file maps USR-names to identifiers. An identifier can end with an ‘.ast’ suffix, indicating the indentifier is a path to a pch-dump. Otherwise the identifier is regarded as path to a source file which is parsed on-demand. Relative paths are prefixed with ctu-dir, absolute paths are used unmodified during lookup.

Default value: “externalDefMap.txt”

### 2.3.2.70. ctu-invocation-list

The path to the YAML format file containing a mapping from source file paths to command-line invocations represented as a list of arguments. This invocation is used produce the source-file’s AST in case on-demand loading is performed.

Example file content:

    {/main.cpp: [clang++, /main.cpp], other.cpp: [clang++, /other.cpp]}

Default value: “invocations.yaml”

### 2.3.2.71. model-path

The analyzer can inline an alternative implementation written in C at the call site if the called function’s body is not available. This is a path where to look for those alternative implementations (called models).

Default value: (empty string)

### 2.3.2.72. ctu-phase1-inlining

Controls which functions will be inlined during the first phase of the ctu analysis. If the value is set to ‘all’ then all foreign functions are inlinied immediately during the first phase, thus rendering the second phase a noop. The ‘ctu-max-nodes-*’ budge has no effect in this case. If the value is ‘small’ then only functions with a linear CFG and with a limited number of statements would be inlined during the first phase. The long and/or nontrivial functions are handled in the second phase and are controlled by the ‘ctu-max-nodes-*’ budge. The value ‘none’ means that all foreign functions are inlined only in the second phase, ‘ctu-max-nodes-*’ budge limits the second phase.

Accepted values: “none”, “small”, “all”.

Default value: “small”

### 2.3.2.73. c++-inlining

Controls which C++ member functions will be considered for inlining.

Accepted values: “constructors”, “destructors”, “methods”.

Default value: “destructors”

### 2.3.2.74. exploration_strategy

Accepted values: “dfs”, “bfs”, “unexplored_first”, “unexplored_first_queue”, “unexplored_first_location_queue”, “bfs_block_dfs_contents”.

Default value: “unexplored_first_queue”

### 2.3.2.75. silence-checkers

A semicolon separated list of checker and package names to silence. Silenced checkers will not emit reports, but the modeling remain enabled.

Default value: (empty string)

### 2.3.2.76. ipa

Controls the mode of inter-procedural analysis.

Accepted values: “none”, “basic-inlining”, “inlining”, “dynamic”, “dynamic- bifurcate”.

Default value: “inlining” (in shallow mode) / “dynamic-bifurcate” (in deep mode)