Segmentation fault on pointer deference

MaskRay / ccls

C/C++/ObjC language server supporting cross references, hierarchies, completion and semantic highlighting

Apache License 2.0

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Observed behavior

Work on a fresh new .c file when trying to deference a pointer ccls crashed.

Did not create a compile_commands.json, just set ccls to accept my folder as project root and started coding. (Detailed info in reproduce section).

Expected behavior

ccls to either give me error information or otherwise auto-complete suggestions.

Steps to reproduce

Follow the build steps ccls/wiki/Build
- (cloned commit 41e7d6a this morning, but error also occurs in 4711fd3)
- Downloaded the latest llvm (9.0.1) this morning (but the problem was also occurring when I was using 9.0.0)
Open spacemacs (I use the develop branch w/ commit 30250403a but problem also occurs in f4f95d28f) along with C/C++-layer

open the following c file


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct Node { void data; struct Node left; // lesser struct Node right; // greater } Node, Tree;

int main (int argc, char argv[]) { Tree insert (char, Tree);

return 0;

}

Tree insert (char word, Tree tree) { Tree tree_p = &tree; int compare;

while (*tree_p)
{
    compare = strcmp (word, (char*)(*tree_p)->);
    if (compare > 0)
    {
        tree_p = &(*tree_p)->right;
    }

}

}

![ccls-issue](https://user-images.githubusercontent.com/25406664/74667013-8c48f500-5170-11ea-9338-bad34c6055df.jpg)

This error (see screenshot bubble) also occurred in the previous version of ccls I was using which I had been using `4711fd3` for a long time without issue.

my `*Messages*` log shows (its short b/c I was reproducing not b/c any incorrect setup)

LSP :: Connected to [ccls:11761 status:starting]. dap-gdb-lldb: webfreak.debug debug extension are not set. You can download it with M-x dap-gdb-lldb-setup LSP :: ccls:11761 initialized successfully ccls: expected expression [4] LSP :: ccls has exited (segmentation fault (core dumped)) Server ccls:11761 exited with status signal. Do you want to restart it? (y or n) n



### System information

* ccls version (`git describe --tags --long`): returns `fatal: No names found, cannot describe anything.` Hope this screenshot of the git log helps.
![image](https://user-images.githubusercontent.com/25406664/74667677-b5b65080-5171-11ea-9c16-17a3314a1883.png)

* clang version: 9.0.1 
Target: x86_64-unknown-linux-gnu
Thread model: posix
* OS:  Ubuntu 18.04.3 LTS
* Editor: `emacs 27.0.60` and `28.0.50` (I sync through dropbox my `.spacemacs.d` and `ccls`)
* Language client (and version): 
[emacs-ccls](https://github.com/MaskRay/emacs-ccls/tree/e5cc4c3e6f40c9c9f0f53e99154c08018eb36944) inside spacemacs it says `ccls-20200204.444` idk if thats enough info to act on but I can tell you I did a fresh install just the other day (might have 1-2 days ago)
+ the problem also occurs in the previous version installed which says `ccls-20191219.913`
+ this package is configured by spacemacs in the [c-c++ layer](https://github.com/syl20bnr/spacemacs/tree/master/layers/%2Blang/c-c%2B%2B)

The ccls initializationOptions is `initializationOptions: {"compilationDatabaseCommand":"","compilationDatabaseDirectory":"","cache":{"directory":".ccls-cache","format":"binary","hierarchicalPath":false,"retainInMemory":2},"capabilities":{"documentOnTypeFormattingProvider":{"firstTriggerCharacter":"}","moreTriggerCharacter":[]},"foldingRangeProvider":true,"workspace":{"workspaceFolders":{"supported":true,"changeNotifications":true}}},"clang":{"excludeArgs":[],"extraArgs":[],"pathMappings":[],"resourceDir":""},"client":{"diagnosticsRelatedInformation":true,"hierarchicalDocumentSymbolSupport":true,"linkSupport":true,"snippetSupport":true},"codeLens":{"localVariables":true},"completion":{"caseSensitivity":2,"detailedLabel":true,"dropOldRequests":true,"duplicateOptional":true,"filterAndSort":true,"include":{"blacklist":[],"maxPathSize":30,"suffixWhitelist":[".h",".hpp",".hh",".inc"],"whitelist":[]},"maxNum":100,"placeholder":true},"diagnostics":{"blacklist":[],"onChange":1000,"onOpen":0,"onSave":0,"spellChecking":true,"whitelist":[]},"highlight":{"largeFileSize":2097152,"lsRanges":false,"blacklist":[],"whitelist":[]},"index":{"blacklist":[],"comments":2,"initialNoLinkage":false,"initialBlacklist":[],"initialWhitelist":[],"maxInitializerLines":5,"multiVersion":0,"multiVersionBlacklist":[],"multiVersionWhitelist":[],"name":{"suppressUnwrittenScope":false},"onChange":false,"parametersInDeclarations":true,"threads":0,"trackDependency":2,"whitelist":[]},"request":{"timeout":5000},"session":{"maxNum":10},"workspaceSymbol":{"caseSensitivity":1,"maxNum":1000,"sort":true},"xref":{"maxNum":2000}}`

#1 0x0000556372fa904f in clang::Sema::CodeCompleteMemberReferenceExpr(clang::Scope*, clang::Expr*, clang::Expr*, clang::SourceLocation, bool, bool, clang::QualType) () #2 0x0000556372d598f8 in clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) () #3 0x0000556372d53502 in clang::Parser::ParseCastExpression(bool, bool, bool&, clang::Parser::TypeCastState, bool) () #4 0x0000556372d55db4 in clang::Parser::ParseCastExpression(bool, bool, clang::Parser::TypeCastState, bool) () #5 0x0000556372d5b5a7 in clang::Parser::ParseParenExpression(clang::Parser::ParenParseOption&, bool, bool, clang::OpaquePtr<clang::QualType>&, clang::SourceLocation&) () #6 0x0000556372d536d5 in clang::Parser::ParseCastExpression(bool, bool, bool&, clang::Parser::TypeCastState, bool) () #7 0x0000556372d55db4 in clang::Parser::ParseCastExpression(bool, bool, clang::Parser::TypeCastState, bool) () #8 0x0000556372d55e3c in clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) () #9 0x0000556372d58081 in clang::Parser::ParseExpressionList(llvm::SmallVectorImpl<clang::Expr*>&, llvm::SmallVectorImpl<clang::SourceLocation>&, llvm::function_ref<void ()>) () #10 0x0000556372d5935c in clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) () #11 0x0000556372d53502 in clang::Parser::ParseCastExpression(bool, bool, bool&, clang::Parser::TypeCastState, bool) () #12 0x0000556372d55db4 in clang::Parser::ParseCastExpression(bool, bool, clang::Parser::TypeCastState, bool) () #13 0x0000556372d56479 in clang::Parser::ParseRHSOfBinaryExpression(clang::ActionResult<clang::Expr*, true>, clang::prec::Level) () #14 0x0000556372d55e4c in clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) () #15 0x0000556372d55ef9 in clang::Parser::ParseExpression(clang::Parser::TypeCastState) () #16 0x0000556372da2012 in clang::Parser::ParseExprStatement(clang::Parser::ParsedStmtContext) () #17 0x0000556372da0c72 in clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::Parser::ParsedAttributesWithRange&) () #18 0x0000556372da1036 in clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) () #19 0x0000556372d9cf19 in clang::Parser::ParseCompoundStatementBody(bool) () #20 0x0000556372d9d78e in clang::Parser::ParseCompoundStatement(bool, unsigned int) () #21 0x0000556372d9d7c2 in clang::Parser::ParseCompoundStatement(bool) () #22 0x0000556372da0a22 in clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::Parser::ParsedAttributesWithRange&) () #23 0x0000556372da1036 in clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) () #24 0x0000556372da1257 in clang::Parser::ParseStatement(clang::SourceLocation*, clang::Parser::ParsedStmtContext) () #25 0x0000556372da38b0 in clang::Parser::ParseWhileStatement(clang::SourceLocation*) () #26 0x0000556372da0843 in clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::Parser::ParsedAttributesWithRange&) () #27 0x0000556372da1036 in clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) () #28 0x0000556372d9cf19 in clang::Parser::ParseCompoundStatementBody(bool) () #29 0x0000556372da76ae in clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) () #30 0x0000556372d14251 in clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) () #31 0x0000556372d3415b in clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::SourceLocation*, clang::Parser::ForRangeInit*) () #32 0x0000556372d0de97 in clang::Parser::ParseDeclOrFunctionDefInternal(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec&, clang::AccessSpecifier) () #33 0x0000556372d0e6f9 in clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*, clang::AccessSpecifier) [clone .part.214] () #34 0x0000556372d0e72f in clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*, clang::AccessSpecifier) () #35 0x0000556372d157d0 in clang::Parser::ParseExternalDeclaration(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*) () #36 0x0000556372d165d0 in clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, bool) () #37 0x0000556372d09ee5 in clang::ParseAST(clang::Sema&, bool, bool) () #38 0x0000556372c820b1 in clang::FrontendAction::Execute() () #39 0x0000556372a9bd2f in ccls::(anonymous namespace)::parse (clang=...) at /usr/scratch/joel/ccls/src/sema_manager.cc:332 #40 0x0000556372a9d466 in ccls::(anonymous namespace)::completionMain (manager_=0x7fffd52c5aa0) at /usr/scratch/joel/ccls/src/sema_manager.cc:493 #41 0x00007f4b4d4644a4 in start_thread (arg=0x7f4b35ffe700) at pthread_create.c:456 #42 0x00007f4b4ccc9eef in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97```

MaskRay / ccls