From 5a77128a8bcf9b090d76b6dc09cf53f0ecd20815 Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Mon, 23 Mar 2026 11:27:05 +0000
Subject: [PATCH 1/6] C++: Disable cpp/implicit-function-declaration on BMN
 databases.

---
 .../Underspecified Functions/ImplicitFunctionDeclaration.ql | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql
index 6a55557cf70b..007ef71a1630 100644
--- a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
+++ b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
@@ -17,6 +17,11 @@ import TooFewArguments
 import TooManyArguments
 import semmle.code.cpp.commons.Exclusions
 
+/*
+ * This query is not compatible with build mode: none databases, and has
+ * no results on those databases.
+ */
+
 predicate locInfo(Locatable e, File file, int line, int col) {
   e.getFile() = file and
   e.getLocation().getStartLine() = line and
@@ -39,6 +44,7 @@ predicate isCompiledAsC(File f) {
 from FunctionDeclarationEntry fdeIm, FunctionCall fc
 where
   isCompiledAsC(fdeIm.getFile()) and
+  not any(Compilation c).buildModeNone() and
   not isFromMacroDefinition(fc) and
   fdeIm.isImplicit() and
   sameLocation(fdeIm, fc) and

From 39056e44771373f23bcd8a561bbf60a6c0122e60 Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Mon, 23 Mar 2026 12:28:12 +0000
Subject: [PATCH 2/6] C++: Change note.

---
 .../change-notes/2026-03-23-implicit-function-declaration.md  | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md

diff --git a/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
new file mode 100644
index 000000000000..8c2c431ec24c
--- /dev/null
+++ b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The "Implicit function declaration" (`cpp/implicit-function-declaration`) query no longer produces results on `build mode: none` databases. These results were found to be very noisy and fundamentally imprecise in this mode.

From bb9873dc8fff136f5e119400ca9cc67f08d0cdb2 Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Fri, 27 Mar 2026 16:40:45 +0000
Subject: [PATCH 3/6] C++: Increase the query precision to high.

---
 .../Underspecified Functions/ImplicitFunctionDeclaration.ql     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql
index 007ef71a1630..0cf6c8b3714e 100644
--- a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
+++ b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
@@ -5,7 +5,7 @@
  * may lead to unpredictable behavior.
  * @kind problem
  * @problem.severity warning
- * @precision medium
+ * @precision high
  * @id cpp/implicit-function-declaration
  * @tags correctness
  *       maintainability

From 50681a3c42fb901cd231e0988c1f3047acbff075 Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Fri, 27 Mar 2026 16:47:31 +0000
Subject: [PATCH 4/6] C++: Add note to the .qhelp.

---
 .../ImplicitFunctionDeclaration.qhelp                        | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp
index 6ff60d383419..d9b5a0220773 100644
--- a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp	
+++ b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.qhelp	
@@ -14,6 +14,9 @@ function may behave unpredictably.</p>
 <p>This may indicate a misspelled function name, or that the required header containing
 the function declaration has not been included.</p>
 
+<p>Note: This query is not compatible with build mode: none databases, and produces
+no results on those databases.</p>
+
 </overview>
 <recommendation>
 <p>Provide an explicit declaration of the function before invoking it.</p>
@@ -26,4 +29,4 @@ the function declaration has not been included.</p>
 <references>
 <li>SEI CERT C Coding Standard: <a href="https://wiki.sei.cmu.edu/confluence/display/c/DCL31-C.+Declare+identifiers+before+using+them">DCL31-C. Declare identifiers before using them</a></li>
 </references>
-</qhelp>
\ No newline at end of file
+</qhelp>

From 4f3108c444156d5a072c19845f7083690a0342b0 Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Fri, 27 Mar 2026 17:04:05 +0000
Subject: [PATCH 5/6] C++: Update change note.

---
 .../src/change-notes/2026-03-23-implicit-function-declaration.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
index 8c2c431ec24c..4fc4808f40c2 100644
--- a/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
+++ b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
@@ -1,4 +1,5 @@
 ---
 category: minorAnalysis
 ---
+* The "Implicit function declaration" (`cpp/implicit-function-declaration`) query has been promoted to `@precision high`.
 * The "Implicit function declaration" (`cpp/implicit-function-declaration`) query no longer produces results on `build mode: none` databases. These results were found to be very noisy and fundamentally imprecise in this mode.

From a9cce1c0fa75b167c549b46ab350d7970929750a Mon Sep 17 00:00:00 2001
From: Geoffrey White <40627776+geoffw0@users.noreply.github.com>
Date: Fri, 27 Mar 2026 17:32:03 +0000
Subject: [PATCH 6/6] C++: Undo increasing query precision.

---
 .../Underspecified Functions/ImplicitFunctionDeclaration.ql     | 2 +-
 .../change-notes/2026-03-23-implicit-function-declaration.md    | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql
index 0cf6c8b3714e..007ef71a1630 100644
--- a/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
+++ b/cpp/ql/src/Likely Bugs/Underspecified Functions/ImplicitFunctionDeclaration.ql	
@@ -5,7 +5,7 @@
  * may lead to unpredictable behavior.
  * @kind problem
  * @problem.severity warning
- * @precision high
+ * @precision medium
  * @id cpp/implicit-function-declaration
  * @tags correctness
  *       maintainability
diff --git a/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
index 4fc4808f40c2..8c2c431ec24c 100644
--- a/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
+++ b/cpp/ql/src/change-notes/2026-03-23-implicit-function-declaration.md
@@ -1,5 +1,4 @@
 ---
 category: minorAnalysis
 ---
-* The "Implicit function declaration" (`cpp/implicit-function-declaration`) query has been promoted to `@precision high`.
 * The "Implicit function declaration" (`cpp/implicit-function-declaration`) query no longer produces results on `build mode: none` databases. These results were found to be very noisy and fundamentally imprecise in this mode.