[ExprInspectionChecker] Improve usability for C

[loladiro]

Summary

Some of the magic functions take arguments of arbitrary type. However,
for semantic correctness, the compiler still requires a declaration
of these functions with the correct type. Since C does not have
argument-type-overloaded function, this made those functions hard to
use in C code. Improve this situation by allowing arbitrary suffixes
in the affected magic functions' names, thus allowing the user to
create different declarations for different types.

[NoQ]

Thanks! This bugged me as well, but i didn't think of this trick :)

docs/analyzer/DebugChecks.rst

Example usage::
     } while(0);  // expected-warning{{SYMBOL DEAD}}
 
 
 - void clang_analyzer_explain(a single argument of any type);
 
   This function explains the value of its argument in a human-readable manner
   in the warning message. You can make as many overrides of its prototype
   in the test code as necessary to explain various integral, pointer,
-  or even record-type values.
+  or even record-type values. To simplify usage in C code (where overloading
+  the function declaration is not allowed), you may append an arbitrary suffix
+  to the function name, without affecting functionality.
 
   Example usage::
 
     void clang_analyzer_explain(int);
     void clang_analyzer_explain(void *);
 
+    // Useful in C code
+    void clang_analyzer_explain_int(int);
+
     void foo(int param, void *ptr) {
       clang_analyzer_explain(param); // expected-warning{{argument 'param'}}
+      clang_analyzer_explain_int(param); // expected-warning{{argument 'param'}}
       if (!ptr)
         clang_analyzer_explain(ptr); // expected-warning{{memory address '0'}}
     }
 
 - void clang_analyzer_dump(a single argument of any type);
 
   Similar to clang_analyzer_explain, but produces a raw dump of the value,
   same as SVal::dump().

lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp

FnCheck Handler = llvm::StringSwitch<FnCheck>(C.getCalleeName(CE))
     .Case("clang_analyzer_eval", &ExprInspectionChecker::analyzerEval)
     .Case("clang_analyzer_checkInlined",
           &ExprInspectionChecker::analyzerCheckInlined)
     .Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
     .Case("clang_analyzer_warnIfReached",
           &ExprInspectionChecker::analyzerWarnIfReached)
     .Case("clang_analyzer_warnOnDeadSymbol",
           &ExprInspectionChecker::analyzerWarnOnDeadSymbol)
-    .Case("clang_analyzer_explain", &ExprInspectionChecker::analyzerExplain)
-    .Case("clang_analyzer_dump", &ExprInspectionChecker::analyzerDump)
+    .StartsWith("clang_analyzer_explain", &ExprInspectionChecker::analyzerExplain)
+    .StartsWith("clang_analyzer_dump", &ExprInspectionChecker::analyzerDump)
     .Case("clang_analyzer_getExtent", &ExprInspectionChecker::analyzerGetExtent)
     .Case("clang_analyzer_printState",
           &ExprInspectionChecker::analyzerPrintState)
     .Case("clang_analyzer_numTimesReached",
           &ExprInspectionChecker::analyzerNumTimesReached)
     .Default(nullptr);
 
   if (!Handler)

test/Analysis/explain-svals.c

+// RUN: %clang_cc1 -triple i386-apple-darwin10 -analyze -analyzer-checker=core.builtin,debug.ExprInspection,unix.cstring -verify %s
+
+struct S {
+  int z;
+};
+
+void clang_analyzer_explain_int(int);
+void clang_analyzer_explain_voidp(void *);
+void clang_analyzer_explain_S(struct S);
+
+int glob;
+
+void test_1(int param, void *ptr) {
+  clang_analyzer_explain_voidp(&glob); // expected-warning-re{{{{^pointer to global variable 'glob'$}}}}
+  clang_analyzer_explain_int(param);   // expected-warning-re{{{{^argument 'param'$}}}}
+  clang_analyzer_explain_voidp(ptr);   // expected-warning-re{{{{^argument 'ptr'$}}}}
+  if (param == 42)
+    clang_analyzer_explain_int(param); // expected-warning-re{{{{^signed 32-bit integer '42'$}}}}
+}
+
+void test_2(struct S s) {
+  clang_analyzer_explain_S(s);      //expected-warning-re{{{{^lazily frozen compound value of parameter 's'$}}}}
+  clang_analyzer_explain_voidp(&s); // expected-warning-re{{{{^pointer to parameter 's'$}}}}
+  clang_analyzer_explain_int(s.z);  // expected-warning-re{{{{^initial value of field 'z' of parameter 's'$}}}}
+}