Merge pull request #18537 from jketema/elifdef

C++: Support `#elifdef`, `#elifndef`, and MSVC's `#import`

cpp/downgrades/59cb96ca699929b63941e81905f9b8de7eed59a6/preprocdirects.ql

@@ -0,0 +1,21 @@
+class PreprocessorDirective extends @preprocdirect {
+  string toString() { none() }
+}
+
+class Location extends @location_default {
+  string toString() { none() }
+}
+
+bindingset[kind]
+int getKind(int kind) {
+  if kind = 14
+  then result = 6 // Represent MSFT #import as #include
+  else
+    if kind = 15 or kind = 6
+    then result = 3 // Represent #elifdef and #elifndef as #elif
+    else result = kind
+}
+
+from PreprocessorDirective ppd, int kind, Location l
+where preprocdirects(ppd, kind, l)
+select ppd, getKind(kind), l

cpp/downgrades/59cb96ca699929b63941e81905f9b8de7eed59a6/upgrade.properties

@@ -0,0 +1,3 @@
+description: Support #elifdef, #elifndef and #import
+compatibility: full
+preprocdirects.rel: run preprocdirects.qlo

cpp/ql/lib/change-notes/2024-01-20-elifdef.md

@@ -0,0 +1,5 @@
+---
+category: feature
+---
+* New classes `PreprocessorElifdef` and `PreprocessorElifndef` were introduced, which represents the C23/C++23 `#elifdef` and `#elifndef` preprocessor directives.
+* A new class `TypeLibraryImport` was introduced, which represents the `#import` preprocessor directive as used by the Microsoft Visual C++ for importing type libraries.

cpp/ql/lib/semmle/code/cpp/Include.qll

@@ -57,9 +57,9 @@ class IncludeNext extends Include, @ppd_include_next {
 }
 
 /**
- * A `#import` preprocessor directive (used heavily in Objective C, and
- * supported by GCC as an extension in C). For example the following code
- * contains one `Import` directive:
+ * An Objective C  `#import` preprocessor directive (supported by GCC as
+ * an extension in C). For example the following code contains one `Import`
+ * directive:
  * ```
  * #import <header3.h>
  * ```
@@ -67,3 +67,14 @@ class IncludeNext extends Include, @ppd_include_next {
 class Import extends Include, @ppd_objc_import {
   override string toString() { result = "#import " + this.getIncludeText() }
 }
+
+/**
+ * A Microsoft `#import` preprocessor directive for importing a type library.
+ * For example the following code contains one `TypeLibraryImport` directive:
+ * ```
+ * #import "library.tlb"
+ * ```
+ */
+class TypeLibraryImport extends Include, @ppd_ms_import {
+  override string toString() { result = "#import " + this.getIncludeText() }
+}

cpp/ql/lib/semmle/code/cpp/Preprocessor.qll

@@ -42,7 +42,7 @@ private class TPreprocessorBranchDirective = @ppd_branch or @ppd_else or @ppd_en
 
 /**
  * A C/C++ preprocessor branch related directive: `#if`, `#ifdef`,
- * `#ifndef`, `#elif`, `#else` or `#endif`.
+ * `#ifndef`, `#elif`, `#elifdef`, `#elifndef`, `#else` or `#endif`.
  */
 class PreprocessorBranchDirective extends PreprocessorDirective, TPreprocessorBranchDirective {
   /**
@@ -74,8 +74,8 @@ class PreprocessorBranchDirective extends PreprocessorDirective, TPreprocessorBr
   }
 
   /**
-   * Gets the next `#elif`, `#else` or `#endif` matching this branching
-   * directive.
+   * Gets the next `#elif`, `#elifdef`, `#elifndef`, `#else` or `#endif` matching
+   * this branching directive.
    *
    * For example `somePreprocessorBranchDirective.getIf().getNext()` gets
    * the second directive in the same construct as
@@ -88,8 +88,8 @@ class PreprocessorBranchDirective extends PreprocessorDirective, TPreprocessorBr
   }
 
   /**
-   * Gets the index of this branching directive within the matching #if,
-   * #ifdef or #ifndef.
+   * Gets the index of this branching directive within the matching `#if`,
+   * `#ifdef` or `#ifndef`.
    */
   private int getIndexInBranch(PreprocessorBranch branch) {
     this =
@@ -102,8 +102,8 @@ class PreprocessorBranchDirective extends PreprocessorDirective, TPreprocessorBr
 }
 
 /**
- * A C/C++ preprocessor branching directive: `#if`, `#ifdef`, `#ifndef`, or
- * `#elif`.
+ * A C/C++ preprocessor branching directive: `#if`, `#ifdef`, `#ifndef`,
+ * `#elif`, `#elifdef`, or `#elifndef`.
  *
  * A branching directive has a condition and that condition may be evaluated
  * at compile-time.  As a result, the preprocessor will either take the
@@ -151,8 +151,8 @@ class PreprocessorBranch extends PreprocessorBranchDirective, @ppd_branch {
  * #endif
  * ```
  * For the related notion of a directive which causes branching (which
- * includes `#if`, plus also `#ifdef`, `#ifndef`, and `#elif`), see
- * `PreprocessorBranch`.
+ * includes `#if`, plus also `#ifdef`, `#ifndef`, `#elif`, `#elifdef`,
+ * and `#elifndef`), see `PreprocessorBranch`.
  */
 class PreprocessorIf extends PreprocessorBranch, @ppd_if {
   override string toString() { result = "#if " + this.getHead() }
@@ -222,6 +222,40 @@ class PreprocessorElif extends PreprocessorBranch, @ppd_elif {
   override string toString() { result = "#elif " + this.getHead() }
 }
 
+/**
+ * A C/C++ preprocessor `#elifdef` directive. For example there is a
+ * `PreprocessorElifdef` on the third line of the following code:
+ * ```
+ * #ifdef MYDEFINE1
+ * // ...
+ * #elifdef MYDEFINE2
+ * // ...
+ * #else
+ * // ...
+ * #endif
+ * ```
+ */
+class PreprocessorElifdef extends PreprocessorBranch, @ppd_elifdef {
+  override string toString() { result = "#elifdef " + this.getHead() }
+}
+
+/**
+ * A C/C++ preprocessor `#elifndef` directive. For example there is a
+ * `PreprocessorElifndef` on the third line of the following code:
+ * ```
+ * #ifdef MYDEFINE1
+ * // ...
+ * #elifndef MYDEFINE2
+ * // ...
+ * #else
+ * // ...
+ * #endif
+ * ```
+ */
+class PreprocessorElifndef extends PreprocessorBranch, @ppd_elifndef {
+  override string toString() { result = "#elifndef " + this.getHead() }
+}
+
 /**
  * A C/C++ preprocessor `#endif` directive. For example there is a
  * `PreprocessorEndif` on the third line of the following code:

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -2318,12 +2318,15 @@ case @preprocdirect.kind of
 | 11 = @ppd_pragma
 | 12 = @ppd_objc_import
 | 13 = @ppd_include_next
+| 14 = @ppd_ms_import
+| 15 = @ppd_elifdef
+| 16 = @ppd_elifndef
 | 18 = @ppd_warning
 ;
 
-@ppd_include = @ppd_plain_include | @ppd_objc_import | @ppd_include_next;
+@ppd_include = @ppd_plain_include | @ppd_objc_import | @ppd_include_next | @ppd_ms_import;
 
-@ppd_branch = @ppd_if | @ppd_ifdef | @ppd_ifndef | @ppd_elif;
+@ppd_branch = @ppd_if | @ppd_ifdef | @ppd_ifndef | @ppd_elif | @ppd_elifdef | @ppd_elifndef;
 
 preprocpair(
     int begin : @ppd_branch ref,

cpp/ql/lib/upgrades/1aa71a4a687fc93f807d4dfeeef70feceeced242/upgrade.properties

@@ -0,0 +1,2 @@
+description: Support #elifdef, #elifndef and #import
+compatibility: partial

cpp/ql/test/library-tests/preprocessor/preprocessor/pp23.cpp

@@ -0,0 +1,15 @@
+// semmle-extractor-options: -std=c++23
+
+#define BAR
+
+#ifdef FOO
+#warning C++23 1
+#elifdef BAR
+#warning C++23 2
+#endif
+
+#ifdef FOO
+#warning C++23 3
+#elifndef FOO
+#warning C++23 3
+#endif

cpp/ql/test/library-tests/preprocessor/preprocessor/ppms.cpp

@@ -0,0 +1,3 @@
+// semmle-extractor-options: --microsoft
+
+#import "test.tlb"

cpp/ql/test/library-tests/preprocessor/preprocessor/preproc.expected

@@ -1,4 +1,13 @@
 | a.h:0:0:0:0 | a.h | 1 | 1 | 1 | 19 | IncludeNext | "a.h" | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 3 | 1 | 3 | 11 | Macro | BAR |  |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 5 | 1 | 5 | 10 | PreprocessorIfdef | FOO | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 7 | 1 | 7 | 12 | PreprocessorElifdef | BAR | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 8 | 1 | 8 | 16 | PreprocessorWarning | C++23 2 | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 9 | 1 | 9 | 6 | PreprocessorEndif | N/A | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 11 | 1 | 11 | 10 | PreprocessorIfdef | FOO | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 13 | 1 | 13 | 13 | PreprocessorElifndef | FOO | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 14 | 1 | 14 | 16 | PreprocessorWarning | C++23 3 | N/A |
+| pp23.cpp:0:0:0:0 | pp23.cpp | 15 | 1 | 15 | 6 | PreprocessorEndif | N/A | N/A |
 | pp.cpp:0:0:0:0 | pp.cpp | 1 | 1 | 1 | 16 | PreprocessorIf | defined(FOO) | N/A |
 | pp.cpp:0:0:0:0 | pp.cpp | 3 | 1 | 3 | 19 | PreprocessorElif | !defined(BAR) | N/A |
 | pp.cpp:0:0:0:0 | pp.cpp | 4 | 1 | 4 | 11 | Macro | BAR |  |
@@ -40,3 +49,6 @@
 | pp.h:0:0:0:0 | pp.h | 7 | 1 | 11 | 8 | Macro | MULTILINE | world a long |
 | pp.h:0:0:0:0 | pp.h | 13 | 1 | 14 | 11 | PreprocessorUndef | MULTILINE | N/A |
 | pp.h:0:0:0:0 | pp.h | 16 | 1 | 17 | 8 | Include | "pp.h" | N/A |
+| ppms.cpp:0:0:0:0 | ppms.cpp | 3 | 1 | 3 | 18 | TypeLibraryImport | "test.tlb" | N/A |
+| test.tlh:0:0:0:0 | test.tlh | 1 | 1 | 1 | 12 | PreprocessorPragma | once | N/A |
+| test.tlh:0:0:0:0 | test.tlh | 3 | 1 | 3 | 21 | PreprocessorWarning | type library | N/A |

cpp/ql/test/library-tests/preprocessor/preprocessor/test.tlh

@@ -0,0 +1,3 @@
+#pragma once
+
+#warning type library