Merge pull request #20232 from igfoo/igfoo/SloppyGlobal

C++: SloppyGlobal: Don't alert on template instantiations, only the template

Author: igfoo

cpp/ql/src/Best Practices/SloppyGlobal.ql

@@ -14,6 +14,9 @@ import semmle.code.cpp.ConfigurationTestFile
 from GlobalVariable gv
 where
   gv.getName().length() <= 3 and
+  // We will give an alert for the TemplateVariable, so we don't
+  // need to also give one for each instantiation
+  not gv instanceof VariableTemplateInstantiation and
   not gv.isStatic() and
   not gv.getFile() instanceof ConfigurationTestFile // variables in files generated during configuration are likely false positives
 select gv,

cpp/ql/src/change-notes/2025-08-15-short-global-name-template-instantiations.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The `cpp/short-global-name` query will no longer give alerts for instantiations of template variables, only for the template itself.

cpp/ql/test/query-tests/Best Practices/SloppyGlobal/SloppyGlobal.expected

@@ -1,2 +1,7 @@
 | main.cpp:3:5:3:5 | x | Poor global variable name 'x'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |
 | main.cpp:4:5:4:6 | ys | Poor global variable name 'ys'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |
+| main.cpp:9:5:9:6 | v1 | Poor global variable name 'v1'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |
+| main.cpp:10:5:10:6 | v2 | Poor global variable name 'v2'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |
+| main.cpp:12:5:12:5 | v3 | Poor global variable name 'v3'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |
+| main.cpp:14:5:14:5 | v4 | Poor global variable name 'v4'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |
+| main.cpp:16:5:16:5 | v5 | Poor global variable name 'v5'. Prefer longer, descriptive names for globals (eg. kMyGlobalConstant, not foo). |

cpp/ql/test/query-tests/Best Practices/SloppyGlobal/main.cpp

@@ -5,3 +5,19 @@ int ys[1000000]; // BAD: too short
 int descriptive_name; // GOOD: sufficient
 
 static int z; // GOOD: not a global
+
+int v1; // BAD: too short
+int v2; // BAD: too short
+template <typename T>
+T v3; // BAD: too short
+template <typename T>
+T v4; // BAD: too short
+template <typename T>
+T v5; // BAD: too short
+
+void use_some_fs() {
+    v2 = 100;
+    v4<int> = 200;
+    v5<int> = 300;
+    v5<const char *> = "string";
+}