Address config issues: #1599, #1790 (#1807)

* addresses #1599, #1790

* Update all configs when c_cpp_properties.json is parsed

Author: bobbrow

Extension/src/LanguageServer/configurations.ts

@@ -141,11 +141,14 @@ export class CppProperties {
         console.assert(rootPath !== undefined);
         this.currentConfigurationIndex = new PersistentFolderState<number>("CppProperties.currentConfigurationIndex", -1, rootPath);
         this.configFolder = path.join(rootPath, ".vscode");
-        this.resetToDefaultSettings(this.currentConfigurationIndex.Value === -1);
-
+        
         let configFilePath: string = path.join(this.configFolder, "c_cpp_properties.json");
         if (fs.existsSync(configFilePath)) {
             this.propertiesFile = vscode.Uri.file(configFilePath);
+            this.parsePropertiesFile();
+        }
+        if (!this.configurationJson) {
+            this.resetToDefaultSettings(this.CurrentConfiguration === -1);
         }
 
         this.configFileWatcher = vscode.workspace.createFileSystemWatcher(path.join(this.configFolder, this.configurationGlobPattern));
@@ -452,13 +455,27 @@ export class CppProperties {
             // the system includes were available.
             this.configurationIncomplete = false;
 
+            // Update intelliSenseMode, compilerPath, cStandard, and cppStandard with the defaults if they're missing.
             let dirty: boolean = false;
             for (let i: number = 0; i < this.configurationJson.configurations.length; i++) {
                 let config: Configuration = this.configurationJson.configurations[i];
                 if (config.intelliSenseMode === undefined) {
                     dirty = true;
                     config.intelliSenseMode = this.getIntelliSenseModeForPlatform(config.name);
                 }
+                // Don't set the default if compileCommands exist, until it is fixed to have the correct value.
+                if (config.compilerPath === undefined && this.defaultCompilerPath && !config.compileCommands) {
+                    config.compilerPath = this.defaultCompilerPath;
+                    dirty = true;
+                }
+                if (!config.cStandard && this.defaultCStandard) {
+                    config.cStandard = this.defaultCStandard;
+                    dirty = true;
+                }
+                if (!config.cppStandard && this.defaultCppStandard) {
+                    config.cppStandard = this.defaultCppStandard;
+                    dirty = true;
+                }
             }
 
             if (this.configurationJson.version !== configVersion) {
@@ -475,24 +492,13 @@ export class CppProperties {
                 }
             }
 
-            // Update the compilerPath, cStandard, and cppStandard with the default if they're missing.
-            let config: Configuration = this.configurationJson.configurations[this.CurrentConfiguration];
-            // Don't set the default if compileCommands exist, until it is fixed to have the correct value.
-            if (config.compilerPath === undefined && this.defaultCompilerPath && !config.compileCommands) {
-                config.compilerPath = this.defaultCompilerPath;
-                dirty = true;
-            }
-            if (!config.cStandard && this.defaultCStandard) {
-                config.cStandard = this.defaultCStandard;
-                dirty = true;
-            }
-            if (!config.cppStandard && this.defaultCppStandard) {
-                config.cppStandard = this.defaultCppStandard;
-                dirty = true;
-            }
-
             if (dirty) {
-                fs.writeFileSync(this.propertiesFile.fsPath, JSON.stringify(this.configurationJson, null, 4));
+                try {
+                    fs.writeFileSync(this.propertiesFile.fsPath, JSON.stringify(this.configurationJson, null, 4));
+                } catch {
+                    // Ignore write errors, the file may be under source control. Updated settings will only be modified in memory.
+                    vscode.window.showWarningMessage('Attempt to update "' + this.propertiesFile.fsPath + '" failed (do you have write access?)');
+                }
             }
         } catch (err) {
             vscode.window.showErrorMessage('Failed to parse "' + this.propertiesFile.fsPath + '": ' + err.message);